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  • 1990-1994  (73)
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Materialart
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  • 1990-1994  (73)
  • 1970-1974  (1.154)
  • 1920-1924
  • 1915-1919
  • 1840-1849
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  • 1
    Digitale Medien
    Digitale Medien
    Biology and ultrastructure of the mycophagus, soil testate amoeba, Phryganella acropodia (Rhizopoda, Protozoa) (1990)
    Springer
    Biology and fertility of soils 9 (1990), S. 101-109 
    Details
    ISSN: 1432-0789
    Schlagwort(e): Phryganella acropodia ; Testate amoeba ; Growth rate ; Rhizopoda ; Feeding ; Fungal species ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Geologie und Paläontologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary Clones of Phryganella acropodia were cultivated under different trophic conditions with bacteria as the food source. The doubling time was estimated to be 3 days. The edibility of four species of fungi, Aspergillus niger, Cunninghamella echinulata, Penicillium echinulatum and Stilbella bulbicola, was tested, but only Penicillium enchinulatum and Stilbella bulbicola were eaten and digested by the amoeba. An ultrastructure examination showed that there are two contractile vacuoles, many dictyosomes, a single nucleus with several nucleoli, and peroxisomes. The pseudopodia are filiform when attached to the substrate but change to lobose when the animal is floating. A thin organic membrane covers the aperture of resting forms.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00335791
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  • 2
    Digitale Medien
    Digitale Medien
    Differing microvasculature in the two major types of gastric carcinoma: a conventional, ultrastructural and ultrastructural immunolocalization study of von Willebrand factor (1990)
    Springer
    Virchows Archiv 417 (1990), S. 29-35 
    Details
    ISSN: 1432-2307
    Schlagwort(e): Gastric carcinoma ; Capillaries ; von Willebrand factor ; Ultrastructure ; Immuno-electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The microvasculature of the stroma of human gastric carcinoma was studied by immuno-electron microscopy for factor VIII/von Willebrand factor (vWF) and conventional electron microscopy. In differentiated type (intestinal) gastric carcinoma (9 cases), capillaries were distributed more densely around carcinoma cell nests. vWF was localized in endothelial cells and neighbouring stroma. Ultrastructurally, capillary endothelial cells showed considerable hypertrophic changes with well-developed rough endoplasmic reticulum (rER). vWF was localized in well-developed rER, granules, Weibel-Palade bodies (WPB), in the vascular lumen as clusters, and diffusely deposited in the subendothelium. This indicates that endothelial cells in this group are transformed into a state of active protein production. In undifferentiated type (diffuse) gastric carcinoma (12 cases), capillaries were uniformly distributed and endothelial hypertrophic changes were less remarkable. vWF was localized in WPB, scanty rER and subendothelial matrix. Solid capillary buds were observed in both types; they were composed of a solid strand of endothelial cells without a visible lumen. Our results reveal that the microvasculature in tumour stroma differs significantly according to its histological type.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01600106
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  • 3
    Digitale Medien
    Digitale Medien
    Small mucus-granule-containing ciliated cells in the human gastric mucosa: a transitional form to metaplastic ciliated cells (1990)
    Springer
    Virchows Archiv 417 (1990), S. 37-41 
    Details
    ISSN: 1432-2307
    Schlagwort(e): Mucus-granule-containing ciliated cell ; Ciliated metaplasia ; Transitional form ; Gastric mucosa ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Ciliated cells were found in the gastric mucosa in close association with intestinal metaplasia, mainly in the pyloric mucosa, of Japanese patients. The occurrence of ciliated cells is believed to be an acquired phenomenon and is considered to be a type of metaplasia; the term “ciliated metaplasia” is used to describe this phenomenon. Ciliated cells are found in the basal part of the glands among normal-looking mucous cells, mucous neck cells and neuroendocrine cells, but never on the surface or in foveolar epithelium. In ciliated cellcontaining glands, mitoses were noted in the neck region and the ultrastructural features of these cells were identical to those of undifferentiated neck cells. However, cell metaplasia from undifferentiated cells to metaplastic ciliated cells has never been demonstrated previously. The small mucus-granule-containing ciliated cells found in our present study may arise subsequent to division of undifferentiated neck cells into mucous cells with some daughter cells then exhibiting differentiation characteristics specific to ciliated cells. Thus they contain a mixture of both small mucus granules and numerous basal bodies and cilia, at the same time as a transitional form.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01600107
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  • 4
    Digitale Medien
    Digitale Medien
    Morphometric comparison of mitochondria and myofibrils of cardiomyocytes between hypertrophic and dilated cardiomyopathies (1990)
    Springer
    Virchows Archiv 416 (1990), S. 473-478 
    Details
    ISSN: 1432-2307
    Schlagwort(e): Cardiomyopathies ; Ultrastructure ; Morphometry ; Mitochondria ; Myofibrils
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary We performed an ultrastructural, morphometric comparison of mitochondria and myofibrils of cardiomyocytes using endomyocardial biopsy specimens in hypertrophic cardiomyopathy (HCM) and dilated cardiomyopathy (DCM). Biopsies came from the right ventricular side of the interventricular septum in nine patients with HCM, nine with DCM, and nine controls with arrhythmia and/or ST depression. Morphometric analysis was carried out using electron microscopic photographs and an image analyser. Mitochondria were significantly greater in number and smaller in size in HCM than in the control group. In DCM, the size of mitochondria was also significantly smaller than in the control group, although their number was similar to that of the control group. No statistically significant difference was found regarding the size of mitochondria between HCM and DCM. The percentages of both mitochondrial and myofibrillar areas in cytoplasm were smaller in the DCM than the HCM and control groups, though no difference was seen between the latter two. The ratio of mitochondrial area to myofibrillar area was almost the same in each group. These results suggest increased mitochondrial function to match hypertrophic cardiomyocytes in HCM, and decreased mitochondrial function and cardiomyocytic contractility in DCM.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01600297
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  • 5
    Digitale Medien
    Digitale Medien
    So-called minute chemodectoma of the lung (1990)
    Springer
    Virchows Archiv 417 (1990), S. 113-118 
    Details
    ISSN: 1432-2307
    Schlagwort(e): Minute chemodectoma ; Lung ; Ultrastructure ; Immunohistochemistry
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary So-called minute pulmonary chemodectoma is a curious, small lung tumour found mainly in women. The nature and origin of the proliferating cells are still obscure. In the first report on the tumour, the component cells were described as resembling chemoreceptor cells and the tumour was named chemodectoma. However, electron microscopic studies of the tumour have revealed no evidence of neuronal characteristics and have shown a close resemblance to meningothelial cells. In this study, the electron microscopic findings were similar to those previously reported but in one of the two cases, tumour cells were filled with abundant cytofilaments, giving them an occasional dense, patch-like appearance. Immunostaining for myosin and vimentin was positive in all tumour cells, but epithelial membrane antigen staining was not seen. These findings indicate that the tumour might have its origin from muscle cells.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02190528
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  • 6
    Digitale Medien
    Digitale Medien
    The ultrastructure of signet-ring cell non-Hodgkin's lymphoma (1990)
    Springer
    Virchows Archiv 417 (1990), S. 395-404 
    Details
    ISSN: 1432-2307
    Schlagwort(e): Ultrastructure ; Non-Hodgkin's lymphoma ; Signet-ring cell ; Endoplasmic reticulum ; Multivesicular body
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary New ultrastructural findings are reported from two lymphomas of vacuolar signet-ring cell morphology (SR+), one of B cell and one of T cell lineage. When these lymphomas were compared ultrastructurally a difference in the relationship of the endoplasmic reticulum (ER) to the vacuole was noted, although the fine structure of the vacuoles themselves was similar and they were interpreted as giant multivesicular bodies (mvbs). Smooth ER was found near the vacuoles in both cases. Dark mvbs with a complex, reticulate form are emphasised as readily identified but hitherto unreported cell components in these tumours. A further B cell lymphoma of centroblastic/centrocytic type which was SR− was found to be rich in mvbs and may be a transitional form between SR− and SR+ lymphomas. In addition, the occurrence of mvbs has been studied quantitatively in a number of other lymphomas and in B and T lymphocytes in reactive nodes. Although increased numbers of mvbs were found in neoplastic compared with reactive lymphocytes, and in T compared with B cell lymphomas, these differences were not statistically significant. The possible roles of endoplasmic reticulum and mvbs in the generation of SR+ change are discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01606028
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  • 7
    Digitale Medien
    Digitale Medien
    Occurrence and prevention of contraction bands in Purkinje fibres, transitional cells and working myocardium during global ischaemia (1990)
    Springer
    Virchows Archiv 417 (1990), S. 463-471 
    Details
    ISSN: 1432-2307
    Schlagwort(e): Purkinje fibres ; Transitional cells ; Working myocardium ; Global ischaemia ; Ultrastructure ; Contraction state
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Contraction bands usually occur in the intramural working myocardium following post-ischaemic reperfusion. In the subendocardium, however, they are found during ischaemia. Thus, we ascertained the contraction states of Purkinje fibres, transitional cells, subendocardial and intramural parts of the working myocardium during 30 min global ischaemia at 25° C. The effects with and without myocardial protection were compared. At the onset of pure ischaemia contraction bands are completely lacking in all cell types. During pure ischaemia contraction bands are found in all subendocardial cell types but not in the intramural working myocardium. A peak of pathological contraction states is found in the intramural working myocardium at the onset (0 min), in the subendocardial working myocardium at 10 min, in the transitional cells and Purkinje fibres at 30 min of pure ischaemia. Histidine-, tryptophan-, ketoglutarate-enriched (HTK) cardioplegia prevents contraction bands completely at the onset of ischaemia and prevents both contraction bands and pathological contraction states during ischaemia almost completely. Striking differences in the physiological contraction states are seen only in the working myocardium: HTK cardioplegia brings about dominance of relaxation during ischaemia. These findings may be due mainly to the effects of global ischaemia on the one hand and to catecholamines, calcium and oxygen on the other.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01625725
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  • 8
    Digitale Medien
    Digitale Medien
    Well-differentiated papillary mesothelioma of the peritoneum: A borderline mesothelioma (1990)
    Springer
    Virchows Archiv 417 (1990), S. 443-447 
    Details
    ISSN: 1432-2307
    Schlagwort(e): Mesothelioma ; Pathology ; Ultrastructure ; Peritoneum
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Well-differentiated papillary mesothelioma (WDPM) is considered to be a distinct subtype of peritoneal mesothelioma. Although the WDPM is usually qualified as benign, the natural history of this lesion has not been clearly established. This report relates to two WDPMs which were found incidentally. In a 51-year-old man the WDPM developed over a period of 5 years into a typically malignant diffuse mesothelioma. Thus, although the WDPM morphologically lacks signs of malignancy, it should be regarded as a borderline mesothelioma.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01606033
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  • 9
    Digitale Medien
    Digitale Medien
    Cytoplasmic argyrophilic inclusions in neurons of pontine nuclei in patients with olivopontocerebellar atrophy: immunohistochemical and ultrastructural studies (1990)
    Springer
    Acta neuropathologica 79 (1990), S. 584-594 
    Details
    ISSN: 1432-0533
    Schlagwort(e): Olivopontocerbellar atrophy ; Argyrophilic inclusion ; Pontine nucleus ; Ubiquitin ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Patients with olivopontocerebellar atrophy (OPCA) were studied, and cytoplasmic inclusions were observed in some of the remaining neurons of the pontine nuclei, nuclei reticularis tegmenti pontis and arcuate nuclei. The cytoplasmic argyrophilic inclusions were demonstrated by silver impregnation techniques such as Bielschowsky and Bodian staining. With hematoxylin and eosin stain, the inclusions were sharply demarcated and appeared pale. The inclusions were not stained by the following routine histological methods: Klüver-Barrera, phosphotungstic acid hematoxylin, Holzer, periodic acid-Schiff, Mallory azan, alcian blue, nile blue, Masson trichrome, Congo red, thioflavine S, oil red O and Sudan black B stains. Immunohistochemistry with anti-ubiquitin antiserum showed that these inclusions were ubiquitinated. However, the inclusions did not react with any of the following antibodies (Abs) or antisera: anti-phosphorylated neurofilament (NF) Ab, anti-nonphosphorylated NF Abs (160 and 200 kDa), anti-paired helical filament antiserum, anti-tau antiserum, anti-tubulin Abs (alpha and beta), anti-microtubule-associated proteins antiserum, anti-glial fibrillary acidic protein antiserum, anti-vimentin Ab, anti-desmin Ab, anti-cytokeratin Abs (low and high molecular weights), anti-actin antiserum, anti-skeletal myosin antiserum and anti-myelin basic protein Ab. Ultrastructurally, the inclusion bodies noted in OPCA were composed primarily of fibrils having a width ranging from about 24 to 40 nm, which were entirely coated with osmiophilic granular material along their whole length. They were occasionally intermingled with a few filaments about 10 nm in width. Electron microscopical examination on silver-impregnated specimens revealed that each granule-coated fibril had a great affinity for silver particles. In elucidating the pathogenesis of OPCA, it was considered to be an important neuropathological finding that some of the remaining pontine neurons affected by OPCA developed characteristic cytoplasmic argyrophilic inclusions.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00294235
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  • 10
    Digitale Medien
    Digitale Medien
    A study of the morphology of the gills of an extreme alkalinity and hyperosmotic adapted teleost Oreochromis alcalicus grahami (boulenger) with particular emphasis on the ultrastructure of the chloride cells and their modifications with water dilution (1990)
    Springer
    Anatomy and embryology 181 (1990), S. 83-98 
    Details
    ISSN: 1432-0568
    Schlagwort(e): Chloride cell ; Teleost ; Gills ; Ultrastructure ; Adaptation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The general gill morphology of Oreochromis alcalicus grahami, a teleost adapted to high salinity and hyperosmosis, is basically similar to that of other teleostean fish. The species has four pairs of gill arches, all of which have well developed filaments. Each of the arches (holobranchs) has two rows of filaments (hemibranchs). Bilaterally situated secondary lamellae branch from the central axis of the filaments. The lamellae reach their maximum size at the middle of the filament, gradually decrease in size and eventually disappear towards the tip of the filament, which is bare. The leading edge of the gill filament and the immediate interlamellar space is covered by a stratified epithelium consisting of pavement cells, mucous cells, chloride cells and undifferentiated cells. The surface of these cells is made up of concentric microridges. The chloride cells were found only on the primary epithelium (filamental epithelium) and very rarely on the secondary epithelium (lamellar epithelium). Two types of chloride cells were observed in the gills of Oreochromis. The superficial chloride cells have fewer mitochondria concentrated towards the basal aspect of the cell, and a network of tubules towards the apical surface and are less electron dense. These cells intercommunicate with the water through an apical pore. The deep chloride cells have numerous diffuse mitochondria intercalated between a fine profuse tubular network and are more electron dense. These cells are covered by one or more layers of pavement cells and thus do not have access to the external surface. After gradual dilution of the lake water in which the fish were kept, both types of chloride cells remained topographically and ultrastructurally distinct. However, in both kinds of cell the mitochondria decreased in number and size. Initially there was an increase in the diameter and the degree of interdigitation of the tubules followed by a gradual decrease. An increase in the quantity of rough endoplasmic reticulum, particularly at the perinuclear region of the cell, was noted. The morphometric analysis of the branchial system indicated that the gills of Oreochromis are well adapted for gas exchange by having numerous and relatively long gill filaments with a high lamellar density. These features provide a large surface for gas exchange which, when coupled with the notably thin water-blood barrier of an average thickness of only 0.83 μm, would facilitate efficient absorption of oxygen by the gills. Oreochromis alcalicus was observed to be incapable of adapting to freshwater. This may have been due to the progressive degeneration of the chloride cells. Also the arrangement of the chloride cells as a continuum from the central venous compartments to the free epithelial surface is a structural feature which may not be amenable to radical functional changes.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00189731
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  • 11
    Digitale Medien
    Digitale Medien
    Developmental cell death: morphological diversity and multiple mechanisms (1990)
    Springer
    Anatomy and embryology 181 (1990), S. 195-213 
    Details
    ISSN: 1432-0568
    Schlagwort(e): Cell death ; Degeneration ; Embryo ; Development ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Physiological cell death is a widespread phenomenon in the development of both vertebrates and invertebrates. This review concentrates on an aspect of developmental cell death that has tended to be neglected, the manner in which the cells are dismantled. It is emphasized that the dying cells may adopt one of at least three different morphological types: “apoptotic”, “autophagic”, and “non-lysosomal vesiculate”. These probably reflect a corresponding multiplicity of intracellular events. In particular, the destruction of the cytoplasm in these three types appears to be achieved primarily by heterophagy, by autophagy and by non-lysosomal degradation, respectively. The various mechanisms underlying both nuclear and cytoplasmic destruction are reviewed in detail. The multiplicity of destructive mechanisms needs to be born in mind in studies of other aspects of cell death such as the signals which trigger it, since different signals probably trigger different types of cell death.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00174615
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  • 12
    Digitale Medien
    Digitale Medien
    Involvement of extraocular muscle in mitochondrial encephalomyopathy (1990)
    Springer
    Acta neuropathologica 80 (1990), S. 118-122 
    Details
    ISSN: 1432-0533
    Schlagwort(e): Mitochondrial encephalomyopathy ; Extraocular muscle ; Ultrastructure ; Mitochondrial myopathy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary We carried out a histological examination of the extraocular muscles (EOMs) in a case of myoclonus epilepsy associated with ragged-red fibers (MERRF) and two cases of mitochondrial myopathy, encephalopathy, laetic acidosis, and stroke-like episodes (MELAS), which did not manifest external ophthalmoplegia clinically. By light microscopy, many granular and vesicular fibers were seen associated with endomysial fibrosis. Electron microscopy revealed that the fibers showed prominent accumulation of abnormal mitochondria, extensive loss of myofibrils, proliferation of free sarcoplasmic reticulum and an increased amount of lipid vacuoles. These changes were more pronounced in MELAS than in MERRF. Hirano bodies were often seen in the subsarcolemmal area of muscle fibers and also in the intramuscular myelinated nerve fibers and axon terminals. These findings suggest the presence of mitochondrial myopathy of the EOMs in cases of MELAS and MERRF.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00308913
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  • 13
    Digitale Medien
    Digitale Medien
    Ultrastructural investigation of the CA1 region of the hippocampus after transient cerebral ischemia in gerbils (1990)
    Springer
    Acta neuropathologica 80 (1990), S. 487-492 
    Details
    ISSN: 1432-0533
    Schlagwort(e): Cerebral ischemia ; Delayed neuronal death ; Gerbil ; Hippocampus ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Ultrastructural damage leading to delayed neuronal death was investigated in the mid-CA1 region of the hippocampus from the stratum (str.) moleculare to oriens after transient bilateral forebrain ischemia in Mongolian gerbils. After ischemia for 5 min without recirculation, mild swelling of the peripheral part of the apical and basal dendrites was already apparent in the str. moleculare and str. oriens. Mitochondria in the dendrites were also swollen in the same area. During recirculation for 12 h to 3 days, swelling of the dendritic cytoplasm persisted with formation of microvacuoles, but swelling of mitochondria receded. Microvacuolation and loss of microtubules were also observed in the proximal part of the dendrites during this period, and swelling and disruption of internal cristae were observed in mitochondria after recirculation for 3 days. The dendrites became severely degenerated after recirculation for 4 days. In the pyramidal cell bodies, no abnormality was observed at the end of ischemia for 5 min, but disaggregation of polyribosomes and swelling of the endoplasmic reticulum were observed 12 h after recirculation. Proliferation of the endoplasmic reticulum in parallel arrays occurred after recirculation for 1 day and persisted. Severe degeneration of the pyramidal cell bodies was obvious after recirculation for 4 days. The findings observed in the present investigation suggested that the neuronal structure most vulnerable to ischemia was the peripheral part of the dendrites and postischemic neuronal damage occurred early in this part of the dendrites.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00294608
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  • 14
    Digitale Medien
    Digitale Medien
    Type C retroviral expression in spontaneous feline olfactory neuroblastomas (1990)
    Springer
    Acta neuropathologica 80 (1990), S. 547-553 
    Details
    ISSN: 1432-0533
    Schlagwort(e): Feline ; Olfactory neuroblastoma ; Type C retrovirus ; Immunocytochemistry ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Three cases of spontaneous olfactory neuroblastoma (ONB) in domestic cats were morphologically and immunocytochemically characterized. Diagnostic light microscopic features included Flexner and Homer-Wright rosettes, while ultrastructurally the cells had neuritic processes, intracellular intermediate filaments, and intercellular junctions. Immunocytochemically, the tumors stained positively for neuron-specific enolase, cytokeratins, and S-100 protein antigens. In each case, a key finding was the identification of numerous mature type C retroviral particles within the tumors. In one case, budding of viral particles from the plasmalemma of tumor cells suggested the source of mature particles. This cat and one other were tested, and both were serologically positive for feline leukemia virus (FeLV). The virus in the tumors was identified as FeLV by polymerase chain reaction and immunocytochemistry. No other neoplasms were found in any of the cats, nor was there similar evidence of active viral infection in other non-tumor tissues, including the brain. Although the relationship between FeLV infection and ONB is uncertain, our findings indicate that FeLV should be investigated as an etiologic agent of ONB.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00294617
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  • 15
    Digitale Medien
    Digitale Medien
    Chronic progressive and relapsing neuromyopathy with massive dilatations of endoplasmic reticulum in muscle fibers (1990)
    Springer
    Acta neuropathologica 80 (1990), S. 611-617 
    Details
    ISSN: 1432-0533
    Schlagwort(e): Intranuclear inclusions ; Endoplasmic reticulum ; Hyaline inclusions ; Striated muscle ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Large intracytoplasmic inclusions arising from the endoplasmic reticulum and nuclear envelope were found in the muscle fibers of a 32-year-old individual with a life-long, chronic and progressive sensory-motor neuropathy. The morphological features of the inclusions were similar to that occasionally reported in the striated muscles in several unrelated conditions as well as to “hyaline” or “colloid” inclusions commonly seen in motor neurons of the brain stem and spinal cord. The chemical nature of the inclusions is not known. Their occurrence in the muscle fibers is probably secondary to chronic denervation.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00307628
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  • 16
    Digitale Medien
    Digitale Medien
    Characterization of intracellular amyloid fibrils in the human choroid plexus epithelial cells (1990)
    Springer
    Acta neuropathologica 80 (1990), S. 597-603 
    Details
    ISSN: 1432-0533
    Schlagwort(e): Choroid plexus ; Amyloid ; Intracellular inclusions ; Ultrastructure ; Immunocytochemistry
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Intracellular inclusions with staining properties of amyloid are very common in the aging choroid plexus epithelial cells. In many ways these inclusions show similarities with the neurofibrillary tangles, found in cerebral cortical neurons in patients with Alzheimer's dementia. We have now designed a purification method for choroid plexus amyloid and performed a transmission and scanning electron miscroscopic study. This shows that one form of choroid plexus inclusions, the Biondi ring, is a homogeneous globule covered with a thin layer of amyloid fibrils. Partial immunochemical characterization of the choroid plexus amyloid reveals that it is different from the neurofibrillary tangles although there are similarities.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00307626
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  • 17
    Digitale Medien
    Digitale Medien
    Re-evaluation of fibroblasts and fibroblast-like cells (1990)
    Springer
    Anatomy and embryology 182 (1990), S. 103-112 
    Details
    ISSN: 1432-0568
    Schlagwort(e): Fibroblast ; Myofibroblast ; Interstitial cell ; Vitamin A storing cell ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Scanning electron microscopic observations of connective tissue cells show a new aspect of the nature of fibroblasts, and the subsequent broad survey of references makes clear that fibroblasts of many tissues have various features which are regarded as atypical of fibroblasts, and at the same time that various connective tissue cells in different organs have features typical of fibroblasts. Both morphological and functional features of fibroblasts are more or less common to those of fibroblast-like cells, and differences among these cells are quantitative rather than qualitative. Therefore, it is almost impossible to set clear-cut criteria for distinguishing genuine fibroblasts from a large population of fibroblast-like cells. The majority of cells sharing features of fibroblasts, if not all, seem to belong to the same population of cells. They are probably adapted to special functional needs in their own micro-environment that are peculiar to local or pathological or experimental conditions. It is proposed to categorize these cells into subtypes depending on their main functions: 1, fibrogenesis; 2, tissue skeleton or barrier; 3, intercellular communication system; 4, gentle contractile machinery; 5, endocrine activity; and 6, vitamin A-storing. Re-evaluation of fibroblasts and fibroblast-like cells is required to facilitate their better understanding.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00174011
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  • 18
    Digitale Medien
    Digitale Medien
    Structural aspects of oocyte maturation in the blue fox (Alopex lagopus) (1990)
    Springer
    Anatomy and embryology 181 (1990), S. 325-331 
    Details
    ISSN: 1432-0568
    Schlagwort(e): Oocyte maturation ; Ultrastructure ; Fox ; Ovulation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Blood samples were taken weekly from seventeen mature blue fox vixens (average age five years), from late anoestrus until pro-oestrus, and then taken daily. The vixens were sacrificed at various stages of oestrus, and oocytes were collected from ovarian follicles by aspiration, and/or from oviducts by flushing. The structural features of oocyte maturation were related to the time of the luteinizing hormone (LH) peak. On days 1–2 after the LH peak the oocyte nucleus migrated from a central to a peripheral position in the ooplasm and assumed a flattened appearance. The cumulus investment expanded simultaneously and ovulation took place around day 2. On days 2–3 the oocyte nuclear envelope broke down, the nucleoli disappeared, the metaphase of the first meiotic division was reached, the Golgi complexes decreased in size, the perivitelline space enlarged, and all junctional contact between cumulus cell projections and oocyte was disrupted. On days 3–5 the first polar body was extruded, the metaphase of the second meiotic division was reached, and the cumulus cells degenerated. On day 5 the release of cortical granule content was occasionally seen, and from day 6 the oocytes showed signs of degeneration. In a few animals deviant oocyte maturation was noticed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00186904
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  • 19
    Digitale Medien
    Digitale Medien
    Optic nerves in plethodontid salamanders (amphibia, urodela): neuroglia, fiber spectrum and myelination (1990)
    Springer
    Anatomy and embryology 181 (1990), S. 37-48 
    Details
    ISSN: 1432-0568
    Schlagwort(e): Axons ; Astrocytes ; Oligodendrocytes ; Ultrastructure ; Paedomorphosis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary In five species of lungless salamanders, family Plethodontidae, which all show highly developed visual abilities, the ultrastructure of the optic nerve was investigated and the total number of retinal ganglion cell axons, the percentage of myelinated axons, and the volume densities of glia and axons were determined. More than 80% of all axons were smaller than 0.4 μm and only 2–3% were larger than 0.8 μm. In individual nerves the degree of myelination varied between 1 and 9% which is in the range reported for other amphibian species. The miniaturized and highly paedomorphic species Batrachoseps attenuatus was an exception because only very few or even no myelinated axons were present in the nerve, which is unique among gnathostome vertebrates. The five investigated species had total numbers of axons ranging from 26000 in Batrachoseps attenuatus to about 50000 in Plethodon jordani. These numbers are the lowest found among vertebrates with an elaborated visual system. The amount of glial material in the optic nerve varied between 25 and 50%, with larger nerves possessing more glia than smaller ones. Ultrastructural analysis revealed that the optic nerve of each species contained both astrocytes and oligodendrocytes, although often in immature form. In Batrachoseps attenuatus the glia showed features of both astrocytes and oligodendrocytes which reflect an undifferentiated state.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00189726
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  • 20
    Digitale Medien
    Digitale Medien
    An ultrastructural study of early chorionic villus formation in the marmoset monkey (Callithrix jacchus) (1990)
    Springer
    Anatomy and embryology 181 (1990), S. 59-66 
    Details
    ISSN: 1432-0568
    Schlagwort(e): Ultrastructure ; Marmoset ; Chorionic villi
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The ultrastructural morphology of developing chorionic villi in the marmoset monkey (Callithrix jacchus) placenta was studied in pregnant monkeys at known time intervals after ovulation. In samples obtained at 45 days after ovulation the mesoderm, which consists of primitive foetal blood vessels, is seen to extend down into cytotrophoblast columns. Syncytiotrophoblast completely surrounds maternal blood vessels and both basal laminae and endothelial cells of maternal origin show signs of disorganisation and degradation. Syncytiotrophoblast is first observed to breach the maternal circulation in samples collected from animals at 60 days after ovulation; this results in discrete haemochorial villi randomly distributed throughout the placental bed. Samples obtained at 80 days after ovulation and term placental samples (145 days after ovulation) exhibit tertiary haemochorial villi throughout the placenta, similar to those seen randomly distributed at 60 days after ovulation.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00189728
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  • 21
    Digitale Medien
    Digitale Medien
    Early development and myogenesis of the posterior anuran lymph hearts (1990)
    Springer
    Anatomy and embryology 181 (1990), S. 75-82 
    Details
    ISSN: 1432-0568
    Schlagwort(e): Anuran lymph hearts ; Development ; Ultrastructure ; Myogenesis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The early development of anuran posterior lymph hearts studied by light- and electron-microscopy in frog larval stages 25–29 (Gosner 1960) can be subdivided into three phases. In phase I, mesenchymal myogenic cells are found, each possessing a single 9 + 0 cilium and numerous filopode-like processes aggregated near the vena caudalis lateralis, forming up to three metameric organ anlagen arranged like a cuff around the preexisting lymphatics (stages 26/27). In phase II, cell proliferation starts at stage 28 within the lymph heart wall as does the formation of primarily polynuclear myofibres by fusion of several myoblasts. At this stage immature myofibres show a vast sarcoplasm, a poorly developed SR and only few myofibrils with not yet distinguishable A- and I-bands. In phase III, the afferent and efferent valves are formed at the onset of pulsation in stage 29. Contractile myofibres contain large glycogen fields and a considerable amount of myofibrils which frequently branch and show distinct Z-lines, A-, I-, H- and M-bands; 1–3 cilia were found lying within a channel-like cell invagination. The peculiarities of organogenesis and myofibre development are discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00189730
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  • 22
    Digitale Medien
    Digitale Medien
    Rosenthal fibres: an immunohistochemical, ultrastructural and immunoelectron microscopic study (1990)
    Springer
    Acta neuropathologica 79 (1990), S. 456-460 
    Details
    ISSN: 1432-0533
    Schlagwort(e): Rosenthal fibers ; Immunohistochemistry ; Ultrastructure ; Neoplastic and reactive astrocytes
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The nature of Rosenthal fibres (RF) was investigated in eight cases each of low-grade astrocytoma and reactive gliosis using immunohistochemical (IH) staining for glial fibrillary acidic protein (GFAP), electron microscopy (EM) and immunoelectron microscopy (IEM) by immunogold labelling technique. By IH under light microscopy (LM), three types of RF were seen, uniformly positive (type I), rim positive (type II) and completely negative (type III). EM showed variation in structural pattern of RF. Some RF contained large amount of glial filaments (GF) intermingled with RF while others with a large amount of electron dense material and less GF. Thus, the presence and amount of GF in RF appear to be responsible for the different types of IH staining under LM. IEM showed that all RF including the ones consisting of entirelh amorphous material possess immunoreactivity for GFAP. It is suggested that RF formation is a two-stage process, staring with excessive accumulation of GF within astrocytic processes followed by their gradual alteration into electron-dense amorphous material under the influence of some unknown metablic or other factors. The quantitative analysis of different types of RF suggests a difference in the rate of formation of RF in neoplastic and reactive conditions.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00308723
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  • 23
    Digitale Medien
    Digitale Medien
    Alphaherpesvirus saimiri infection in rabbits (1990)
    Springer
    Acta neuropathologica 79 (1990), S. 551-557 
    Details
    ISSN: 1432-0533
    Schlagwort(e): Cutaneous nerves ; Neuropathy ; Ultrastructure ; Herpesvirus ; Rabbits
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary A light and electron microscopic study was undertaken to determine pathological changes in cutaneous spinal nerves of rabbits following intradermal inoculation with alphaherpesvirus saimiri (αHVS) isolate KM 322. Infected rabbits were killed at 3, 10, 17, 45 days and 2 years after infection. No abnormalities were seen at 3 days postinoculation. In the nerves of the rabbits killed at 10, 17 and 45 days after infection, axonal (Wallerian-type) degeneration was the main pathological feature. Regeneration, manifested by axonal sprouting, was observed in the nerves of the rabbits killed at 45 days post-inoculation. Neural fibrosis and paucity of unmyelinated axons was the final outcome. The severity of the neural damage not only varied according to the progression of the disease but between nerves taken from the same rabbit. This was probably associated with variation in the numbers of virus particles that had reached the dorsal root ganglion of the dermatome served by a particular nerve. Since αHVS (isolate KM 322) provides a model system for the study of virus latency in dorsal root ganglia, and consequently for the study of varicellazoster infection in man, these findings give further insight into the pathology of herpetic neuropathy.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00296116
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  • 24
    Digitale Medien
    Digitale Medien
    Histological, ultrastructural and chromatographical discrimination of phospholipids in meningiomas (1990)
    Springer
    Acta neuropathologica 80 (1990), S. 255-259 
    Details
    ISSN: 1432-0533
    Schlagwort(e): Meningioma ; Phospholipid ; Psammoma ; Ultrastructure ; Chromatography
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Phospholipids in meningiomas were studied by light and electron microscopy, and by high-performance liquid chromatography. They were microscopically demonstrated in six of the ten cases by Sudan III staining after the fixation with potassium dichromate. However, the conventional ultrastructural fixation with glutaraldehyde and osmium tetroxide failed to confirm phospholipids, as most of them were dissolved during dehydration. In contrast, the specimens pretreated with tannic acid before osmication ultrastructurally retained phospholipids which were represented by multilamellar bodies or ribbon-like rings. Both were found in 23 of the 30 cases within the cytoplasm, among the plasma membranes and in the extracellular matrices. The outermost lamella or ribbon showed a direct continuity from the neighbouring plasma membranes of the cytoplasm or the mitochondria. The multilamellar bodies showed an overall distribution, while the ribbon-like rings were predominantly distributed around the psammoma bodies. Precipitation of hydroxyapatite crystals within the ribbon-like rings resulted in matrix minerals of psammoma bodies. Chromatographical analyses of meningiomas disclosed phospholipids including phosphatidyl ethanolamine, phosphatidyl choline, phosphatidyl serine, sphingomyelin and phosphatidyl inositol in that order. Psammomatous meningiomas contained a higher percentage of phosphatidyl serine than non-psammomatous tumors. Ultrastructural study of synthetic phospholipids adequately treated with tannic acid showed that the multilamellar bodies were similar to phosphatidyl choline, while the ribbon-like rings were similar to phosphatidyl serine. The role of phospholipids in meningiomas is discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00294642
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  • 25
    Digitale Medien
    Digitale Medien
    Hyperplastic and hypertrophic growth of lateral muscle in Dicentrarchus labrax (L.) (1990)
    Springer
    Anatomy and embryology 182 (1990), S. 1-10 
    Details
    ISSN: 1432-0568
    Schlagwort(e): Fish ; Muscle growth ; Hyperplasia ; Hypertrophy ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary In this EM study of lateral muscle in Dicentrarchus labrax, we observed that during the larval period, growth of the presumptive red and white muscle layers occurs both by hypertrophy (as fibres already present at hatching complete their maturation) and by production of new fibres in germinal zones specific to the two muscle layers. In the first half of larval life the presumptive white muscle increases in thickness by the addition, superficially, of new fibres derived from a germinal zone of presumptive myoblasts lying beneath the red muscle layer. In the second half of larval life new fibres produced in this same zone form the intermediate (or pink) muscle layer. Dorsoventrally the myotome grows throughout larval life, largely by addition of new fibres from germinal zones at the hypo- and epi-axial extremities. Towards the end of larval life all these germinal zones are becoming exhausted, but another source of fibres arises as satellite cells, associated with large-diameter presumptive white muscle fibres, are activated to produce new fibres. The addition of small, new fibres gives the white muscle its mosaic appearance. Morphometric analysis of fibre diameters in the white muscle confirms that whereas these hyperplastic processes are important during the larval and juvenile periods, when growth is very rapid, they have ceased by the time the adult stage is attained. By contrast, fibre hypertrophy continues through into adult life. The presumptive red muscle consists initially of a monolayer of fibres present only near the lateral line, and during larval life it grows hypo- and epi-axially by addition of fibres derived from myoblasts already present in these areas at hatching. Lying superficially to the presumptive red muscle monolayer there is a near-continuous layer of external cells with a “flattened” profile. During the second half of larval life, differentiation of these external cells into myoblasts provides the source of new fibres which are added to the red muscle layer. This process, which occurs initially in the region around the lateral line and later spreads outwards, is responsible for the increase in thickness of the red muscle.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00187522
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  • 26
    Digitale Medien
    Digitale Medien
    Pronephric regression during larval life in the sea lamprey, Petromyzon marinus L. (1990)
    Springer
    Anatomy and embryology 182 (1990), S. 41-52 
    Details
    ISSN: 1432-0568
    Schlagwort(e): Lamprey ; Pronephros ; Ultrastructure ; Regression ; Apoptosis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The regression of the pronephric kidney of the lamprey, Petromyzon marinus, is described using histochemical and ultrastructural techniques. Regression begins in the third year of larval life, and by the time the animal enters metamorphosis the tubules have all disappeared. The nephrostomes and the renal corpuscle, however, persist for the remainder of the life cycle and undergo little change in the larva. Iron is present within the tubular epithelium prior to the beginning of degeneration, but as degeneration proceeds iron is observed within the tubule lumina. Acid phosphatase is noted within the tubule epithelia prior to degeneration, but as degeneration proceeds acid phosphatase is also observed within the intertubular area. Features of tubular regression include a prominent and highly folded basal lamina, numerous cytoplasmic inclusions, and dense bodies in the epithelia and lumina. The intertubular region is invaded by lymphocytes, granulocytes, plasma cells, and macrophages. The process of pronephric regression possesses many features of the process of apoptosis, which has been noted in the regression of larval organs in other vertebrates.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00187526
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  • 27
    Digitale Medien
    Digitale Medien
    Distribution of serotonin in the caudal neurosecretory complex (1990)
    Springer
    Anatomy and embryology 181 (1990), S. 491-498 
    Details
    ISSN: 1432-0568
    Schlagwort(e): Serotonin ; Ultrastructure ; Caudal Neurosecretory Complex ; Neuroendocrine ; Monoamines
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The caudal neurosecretory complex (CNc) of poecilids has previously been shown to receive serotonergic inputs. In the present study, immunohistochemical techniques were applied at the light and electron microscopic levels to characterize serotonergic terminals in the neuroendocrine nucleus. A dense plexus of varicose fibers observed in the rostral CNc neuropil was absent in the spinal cords of deafferented fish, indicating that the origin of this input was extranuclear. Ultrastructural study revealed no direct contacts between labeled structures and neuroendocrine cells. Non-synaptic terminals (varicosities) were the predominantly labeled structures in the neuropil. Synaptic terminals were observed on cellular and axonal targets in the CNc. Small cells containing 70 nm dense-core vesicles received serotonergic input on their perikarya. Labeled synapses were also found on unlabeled axon terminals which made axoaxonal synapses on neuroendocrine processes. Non-synaptic terminals may be responsible for a variety of serotonin-mediated effects in the CNc. Synaptic interactions with local catecholaminergic and afferent cholinergic inputs to the CNc are likely.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02433796
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  • 28
    Digitale Medien
    Digitale Medien
    Light and electron microscopic morphology of the temporomandibular joint in growing and mature crab-eating monkeys (Macaca fascicularis): the condylar articular layer (1990)
    Springer
    Anatomy and embryology 181 (1990), S. 499-511 
    Details
    ISSN: 1432-0568
    Schlagwort(e): Mandibular condyle ; Articular tissue layer ; Ultrastructure ; Maturation ; Load-dependence ; Macaca fascicularis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary In an attempt to establish maturational alterations in the morphology of the articular tissue layer, mandibular condyles of four immature and four mature male monkeys (Macaca fascicularis) were studied using light microscopy as well as scanning and transmission electron microscopy. Specimens were fixed in situ by perfusion in the presence of ruthenium red to stabilize proteoglycans. Preparations intended for observation in the scanning electron microscope were first dehydrated and sputtered for the examination of articular surfaces, and afterwards treated with trypsin to expose the spatial arrangement of collagen fibrils. Gross anatomical relations between joint components indicated that the anterior and central, but not the posterior region of the condylar articular surface can be subject to compressional load. Load-bearing and non-load-bearing regions differed with respect to the morphology of the articular layer. Load-bearing surfaces were covered by a prominent articular surface lamina similar to that observed on articular cartilage. This lamina seemed to constitute an integral part of the articular layer, distinct from the lining of synovial fluid, and to be composed largely of proteoglycans. It was unaffected by maturation. The subjecent, load-bearing articular layer differed markedly in structure, both from articular cartilage, and between immature and mature animals. Articular cells of immature animals were classified as fibroblastlike, but unlike typical fibroblasts, were surrounded by a thin, often incomplete halo of fibril-free pericellular matrix, presumably consisting of proteoglycans. In mature animals, articular cells closely resembled chondrocytes, but exhibited prominent nuclear fibrous laminae, which usually are found only in fibroblasts. Thus, the load-bearing part of the articular layer seems to undergo a maturation-dependent metaplastic conversion, from a dense connective tissue with some features of fibrocartilage, to a fibrocartilage-like tissue containing chrondrocytelike cells with some features of fibroblasts. This conversion might reflect an adaptation to a maturation-associated increase in articular stress.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02433797
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  • 29
    Digitale Medien
    Digitale Medien
    The ultrastructure of dysplastic naevi: comparison with superficial spreading melanoma and common naevocellular naevi (1990)
    Springer
    Archives of dermatological research 282 (1990), S. 353-362 
    Details
    ISSN: 1432-069X
    Schlagwort(e): Dysplastic naevi ; Superficial spreading melanoma ; Naevocellular naevi ; Ultrastructure ; Melanosomes
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Eleven dysplastic melanocytic naevi with various degrees of dysplasia, as judged by light microscopy, were studied by transmission electron microscopy, and their intra-epidermal melanocytes compared with those of five superficial spreading melanomas and seven common benign naevocellular naevi. Intra-epidermal melanocytes in dysplastic naevi exhibited signs of cellular atypia, which were most pronounced in the dysplastic naevi with histological high-grade dysplasia. A correlation between the degree of dysplasia at the light microscopic level and the degree of cytological atypia at the ultrastructural level was noted, and melanocytes in dysplastic naevi with a high degree of dysplasia had ultrastructural features similar to the melanocytes in superficial spreading melanomas. Our observations support the concept that dysplastic naevi fill the biological gap between benign naevocellular naevi and malignant melanomas and suggest that at least some of the dysplastic naevi must be regarded as potential precursor lesions of malignant melanoma, particularly those exhibiting a high degree of histological dysplasia.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00372084
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  • 30
    Digitale Medien
    Digitale Medien
    Skin changes in variegate porphyria (1990)
    Springer
    Archives of dermatological research 282 (1990), S. 108-114 
    Details
    ISSN: 1432-069X
    Schlagwort(e): Porphyria ; Dermal vessels ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The skin of 20 patients with variegate porphyria (VP) was studied using light, fluorescent, and electron microscopy. Twelve patients had skin symptoms and markedly increased fecal protoporphyrin excretion. Their sun-exposed skin was characterized by homogeneous PAS-positive thickening and IgG deposition in the vessel walls. The basic ultrastructural change was thickening of the vascular walls caused by reduplication of the basal lamina and perivascular deposition of amorphous material. Qualitatively similar but less prominent histopathological changes occurred in sun-protected skin in some of the patients. Six patients had no skin symptoms but an increased porphyrin excretion. The light microscopical changes were comparable to those in the patients with skin symptoms, but the ultrastructural changes were less severe. No abnormal histopathological changes occurred in two symptomless patients who had low lymphocyte protoporphyrinogen oxidase activity but normal fecal porphyrin excretion. These results show that the primary site of skin damage in VP is the vessel wall, and that histopathological changes of the skin also occur in porphyric patients who have never had skin symptoms. Factors determining the occurrence of skin symptoms in VP are discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00493468
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  • 31
    Digitale Medien
    Digitale Medien
    Dynamic ultrastructural changes of the connective tissue sheath of human hair follicles during hair cycle (1990)
    Springer
    Archives of dermatological research 282 (1990), S. 434-441 
    Details
    ISSN: 1432-069X
    Schlagwort(e): Hair cycle ; Human hair follicle ; Connective tissue sheath ; Hyaline membrane ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Ultrastructural changes of the connective tissue sheath (CTS), including the hyaline membrane, of human hair follicles during the hair cycle, were studied in normal scalp skin specimens. In early anagen, the CTS was composed of a thin basal lamina and surrounding collagen tissue. The collagen tissue gradually thickened during the development of the hair and hair follicle. In mature anagen hair follicles, the collagen tissue was separated into three layers. The inner collagen layer, just outside the basal lamina, was thin and composed of collagen fibres running longitudinally parallel to the hair axis. The middle collagen layer was very thick with its collagen fibres running transversely against the hair axis and surrounding the inner hair tissue. Many fibroblasts were present among the collagen fibres in the middle layer, whereas the inner layer contained almost none. In the outer collagen layer, collagen fibres ran in various directions parallel to the outer surface of the outer root sheath cells. In late anagen, the basal lamina became very thick. In catagen, the basal lamine and the inner collagen layer became corrugated and showed oedematous change and degeneration. Surrounding fibroblasts showed active production of new collagen fibres, which seemed to fill the spaces left by the retraction of the hair follicle and hyaline membrane. These ultrastructural changes of the CTS show that there may be dynamic metabolic changes of the connective tissue around human hair follicles during the hair cycle.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00402618
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  • 32
    Digitale Medien
    Digitale Medien
    Intercellular structure in a many-celled magnetotactic prokaryote (1990)
    Springer
    Archives of microbiology 154 (1990), S. 18-22 
    Details
    ISSN: 1432-072X
    Schlagwort(e): Intercellular junctions ; Multicellularity in prokaryotes ; Bacterial magnetotaxis ; Ultrastructure ; Bacterial co-ordination
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract A many-called magnetotactic prokaryote obtained from brackish water was observed to possess intercellular connections at points of contact between the outer membranes of constituent cells. Each aggregate organism consisted of 10 to 30 individual Gram-negative cells containing material with the appearance of poly-β-hydroxybutyrate and magnetosomes of unusual arrangement, structure and composition. The aggregate, which possessed prokaryotic-type flagella arranged at the outwards surfaces of each cell, showed motility indicative of co-ordination between individual component cells. These results suggest that this organism could be a multicellular prokaryote.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00249172
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  • 33
    Digitale Medien
    Digitale Medien
    The vascular architecture of human xenotransplanted tumors: histological, morphometrical, and ultrastructural studies (1990)
    Springer
    Journal of cancer research and clinical oncology 116 (1990), S. 517-524 
    Details
    ISSN: 1432-1335
    Schlagwort(e): Tumor vascularization ; Tumor blood flow ; Xenograft ; Nude mouse ; Vascular corrosion cast ; Ultrastructure ; Electron microscopy ; Heterogeneity ; Vessel morphology ; Morphometry ; Necrosis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary This study was designed to examine the vascular system of human xenotransplanted tumors on nude mice with different complementary morphometrical and morphological methods. The vascular system shows a chaotic arrangement. There is an extreme heterogeneity in the vascular distribution and density. Large avascular regions could be identified in several non-necrotic tumors. There was no clear difference in the vascular density between the center and the periphery of the tumors, nor was there any zonal correlation for the distribution of the necrosis. With three-dimensional corrosion casts it could be demonstrated that clusters of vessels were directly beneath areas almost free of vessels. In the center, vessels often form a sinusoidal system with numerous blind ends without clearly discernible endothelial cells. Numerous irregular tumor-cell-lined sinusoids are visible next to endothelial-lined vessels with transmission electron microscopy. With scanning electron microscopy it could be demonstrated that large-calibre endotheliazed vessels were found in the direct vicinity or in the center of non-viable zones. Even large-calibre vessels have a capillary wall structure. Sometimes, a basement membrane cannot be observed at all or only incompletely. There are numerous indications of vascular discontinuities and leaks with a widespread intercellular occurrence of blood cells.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01613005
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  • 34
    Digitale Medien
    Digitale Medien
    Effects of endogenous and exogenous cholesterol on the ultrastructure and steroid secretion of undifferentiated rat adrenocortical cells in primary culture (1990)
    Springer
    Cell & tissue research 259 (1990), S. 421-427 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Adrenal cortex ; Tissue culture ; Corticosterone ; Ultrastructure ; Lipoproteins ; Mevinolin ; Rat (Sprague-Dawley)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The present study was undertaken to define the effects of lipoprotein-derived cholesterol and endogenous, de novo synthesized cholesterol on the ultrastructure and function of undifferentiated rat adrenocortical cells [lipoprotein (HDL3 and LDL) receptor-negative, zona glomerulosa-like adrenocortical cells] in primary culture. For this purpose human plasma high density lipoprotein (HDL3) or low density lipoprotein (LDL) was added to culture medium devoid of cholesterol. Steroid secretion remained at the low basal level even after addition of lipoproteins, and the amount of intracellular lipid droplets did not increase. When mevinolin (0.96 µg/ml), an inhibitor of cholesterol synthesis, was added to the culture medium, a low secretion of corticosterone was measured both in serum-free and serum-containing media. Ultrastructurally, lipid droplets disappeared after treatment with mevinolin in both media used. At this concentration of mevinolin cell proliferation was similar to that in the controls, but at higher concentrations (4.8 or 9.6 µg/ml) proliferation was inhibited to 42% and 26% in serum-free medium, and 20% and 12% in serum-supplemented medium, respectively. This study demonstrates that cell proliferation and synthesis of corticosterone by undifferentiated rat adrenocortical cells is identical in the absence or presence of exogenous lipoprotein cholesterol. Inhibition of de novo cholesterol synthesis by mevinolin over a period of 7 days does not inhibit corticosterone secretion or proliferation of cells but decreases the amount of intracellular lipid droplets, thus suggesting utilization of intracellular cholesterol esters. However, higher concentrations of mevinolin inhibit proliferation of cells both in serum-free and serum-containing media.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01740768
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  • 35
    Digitale Medien
    Digitale Medien
    Organization of a phyllobranchiate gill from the green shore crab Carcinus maenas (Crustacea, Decapoda) (1990)
    Springer
    Cell & tissue research 260 (1990), S. 495-505 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Cuticle ; Epithelium, branchial ; Gills ; Hemocoel ; Histology ; Ultrastructure ; Carcinus maenas (Crustacea)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The phyllobranchiate gills of the green shore crab Carcinus maenas have been examined histologically and ultrastructurally. Each gill lamella is bounded by a chitinous cuticle. The apical surface of the branchial epithelium contacts this cuticle, and a basal lamina segregates the epithelium from an intralamellar hemocoel. In animals acclimated to normal sea water, five epithelial cell types can be identified in the lamellae of the posterior gills: chief cells, striated cells, pillar cells, nephrocytes, and glycocytes. Chief cells are the predominant cells in the branchial epithelium. They are squamous or low cuboidal and likely play a role in respiration. Striated cells, which are probably involved in ionoregulation, are also squamous or low cuboidal. Basal folds of the striated cells contain mitochondria and interdigitate with the bodies and processes of adjacent cells. Pillar cells span the hemocoel to link the proximal and distal sides of a lamella. Nephrocytes are large, spherical cells with voluminous vacuoles. They are rimmed by foot processes or pedicels and frequently associate with the pillar cells. Glycocytes are pleomorphic cells packed with glycogen granules and multigranular rosettes. The glycocytes often mingle with the nephrocytes. Inclusion of the nephrocytes and glycocytes as members of the branchial epithelium is justified by their participation in intercellular junctions and their position internal to the epithelial basal lamina.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00297229
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  • 36
    Digitale Medien
    Digitale Medien
    The ultrastructure of the intestinal nerve of Remak in the domestic fowl (1990)
    Springer
    Cell & tissue research 260 (1990), S. 601-616 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Autonomic ganglia ; Catecholamines ; Intestines ; Innervation ; Ultrastructure ; Domestic fowl (Aves)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary An ultrastructural study was made of the neurons, satellite cells and vesiculated axons of the intestinal nerve of the domestic fowl. Broad membrane-to-membrane contacts between adjacent nerve cell bodies were sometimes observed. The cell bodies and processes were not always separated from the extracellular space by a capsule of satellite cells. Following fixation using potassium permanganate, catecholamine (CA)-containing neurons in the intestinal nerve, unlike those in the lumbar parasympathetic ganglia, did not possess any small granular vesicles (SGV). Following exposure to noradrenaline, SGV could be demonstrated in the cell bodies of the juxta-ileal ganglia but not the juxta-rectal ganglia of the intestinal nerve. Non-CA axons were examined in tissue from birds that had been pretreated with 6-hydroxydopamine. Approximately one half of the non-CA axons formed axo-somatic contacts. Most of the non-CA axons contained varying proportions of small clear vesicles, large clear vesicles and large granular vescles. Statistical analysis showed that the non-CA axons could not be subdivided according to their vesicle content. CA-axons contained many SGV and were found in close apposition to neuronal somata and processes, and in the neuropil.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00297241
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  • 37
    Digitale Medien
    Digitale Medien
    Histochemical and ultrastructural studies on the enterochromaffin-like cell in the gastric mucosa of the opossum Didelphis albiventris (Marsupialia) (1990)
    Springer
    Cell & tissue research 262 (1990), S. 425-430 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Stomach ; Enteroendocrine cells ; Enterochromaffin-like (ECL) cell ; Enterochromaffin cell (EC) ; Histamine ; Ultrastructure ; Secretory granules ; Didelphis albiventris (Marsupialia)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary An ultrastructural study of enterochromaffin-like (ECL) cells in the gastric mucosa of the white-belly opossum Didelphis albiventris (Marsupialia) was carried out. In parallel, histochemical methods were used at the light-microscopical level to demonstrate argentaffin cells, argyrophilic cells, and serotonin- and histamine-immunoreactive elements. Argentaffin and serotonin-immunoreactive cells were scattered, and argyrophilic cells were numerous, within the full thickness of the mucosa. Argyrophilic cell distribution was similar to that of histamine-immunoreactive elements. At the electron-microscopical level, the oxyntic mucosa of D. albiventris presented endocrine cells with secretory granules morphologically similar to those of the ECL cell of eutherian mammals. However, in this marsupial, the ECL cell exhibited a variable mixture of two distinct types of secretory granules: (1) granules with the morphological appearance of the eutherian ECL cell, and (2) granules morphologically similar to those of the eutherian enterochromaffin (EC) cells. Based on this morphological pattern of the ECL cell granules, it is proposed that in the oxyntic mucosa of the opossum D. albiventris, the EC and ECL cells represent distinct steps in the same line of cell differentiation; the ECL cell should also be a site of histamine storage.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00305239
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  • 38
    Digitale Medien
    Digitale Medien
    Effects of mevinolin, an inhibitor of cholesterol synthesis, on the morphology and function of differentiating and differentiated rat adrenocortical cells in primary culture (1990)
    Springer
    Cell & tissue research 261 (1990), S. 125-132 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Adrenal cortex ; Differentiation ; Tissue culture ; Mevinolin ; Steroids ; Ultrastructure ; Rat (Sprague-Dawley)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Mevinolin, an inhibitor of cholesterol synthesis, was used to study the effect of endogenous cholesterol synthesis on the morphology and function of differentiating and differentiated fetal rat adrenocortical cells grown in primary culture. Upon adrenocorticotrophic hormone (ACTH) stimulation under conditions in which endogenous cholesterol synthesis was inhibited but exogenous (lipoprotein) cholesterol was available, the cells differentiated normally from glomerulosa-like to fasciculata-like cells; the steroid hormone secretion was maximally induced. Under conditions in which cholesterol synthesis was maximally inhibited by mevinolin and the cells had no access to exogenous cholesterol, the cells did not differentiate into fasciculata-like cells; the ACTH-induced steroid response was highly suppressed under these conditions. The addition of either human low-density lipoprotein (LDL) or high-density lipoprotein (HDL3) to the culture medium restored the ACTH-induced differentiation and steroid secretion. Thus, in the absence of exogenous cholesterol, endogenous cholesterol synthesis was a prerequisite for differentiation. In cultures grown in the presence of exogenous cholesterol and ACTH with mevinolin-inhibited cholesterol synthesis and high steroid output, an increase in cytoplasmic lipids was evident, suggesting upregulation of LDL and HDL receptors. The results also demonstrated that induction of phenotypic differentiation from glomerulosalike into fasciculata-like cells can proceed in the presence of a cholesterol synthesis inhibitor like mevinolin; this differentiation in the absence of endogenous cholesterol synthesis is accompanied by the appearance of cytoplasmic cholesterol ester droplets, typical of fasciculata cells.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00329445
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  • 39
    Digitale Medien
    Digitale Medien
    Qualitative and quantitative analysis of granules in atrial appendage cardiocytes in different physiological states (1990)
    Springer
    Cell & tissue research 259 (1990), S. 529-534 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Atrial appendage ; Atrial-specific granules ; Atrial natriuretic polypeptides ; Exocytosis ; Ultrastructure ; Rat (Sprague-Dawley)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Atrial appendage cardiocytes of mammals, including man, contain multiple cytoplasmic granules that vary in number in different physiological states. Using morphologic and comprehensive morphometric techniques, these granules were assessed in Sprague-Dawley rats following dehydration for 5 days, volume-loading by substituting 1% NaCl as drinking water for 7 days, unilateral nephrectomy plus volume-loading for 7 days, and in late term pregnant animals (18–20 days; term ≈21 days). Although principally located in the paranuclear region, granules were observed throughout the sarcoplasm. Cytological features indicative of synthetic activity and granule formation were readily apparent in all groups with the exception of pregnant rats where they were infrequently observed. Granule contents were released by exocytosis and observed in the right appendage of control, dehydrated and nephrectomy/volume-loaded groups and left appendage of volumeloaded animals. Exocytosis was not observed in pregnant animals. By point counting, the proportional volume of cardiocytes occupied by granules (V v ) in controls was significantly greater for right than for left appendage (2.12±0.22% vs 1.29±0.16%; mean±SEM;p〈0.05). A significantly similar difference was found for nephrectomy/volume-loaded animals. There was no significant difference inV v for right appendage between the control and experimental groups; for left appendage there was a significant increase inV v to 2.42±0.09% (p〈0.05) for volume-loaded animals only. Estimation of the maximum diameter of granule profiles in control animals was 238±9 nm and 230±6 nm for right and left appendages, respectively. The profile diameters in the left appendages of dehydrated (202±9 nm) and pregnant (200±7 nm) animals were significantly (p〈0.05) less than those of the control animals. The morphometric findings did not correlate with predictions based upon published biochemical data. In the course of this study, a previously unreported bimembranous, circular to ovoid structure was observed in the cardiocyte sarcoplasm of all animals; the nature and function of this structure is unknown.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01740780
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  • 40
    Digitale Medien
    Digitale Medien
    Fine structural and volumetric changes of lamprey photoreceptor cells during light and dark periods (1990)
    Springer
    Cell & tissue research 259 (1990), S. 33-41 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Photoreceptor cells ; Ultrastructure ; Volumetric change ; Light/dark cycle ; Lampetra japonica (Cyclostomata)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Short photoreceptor cells of the lamprey retina exhibited a 30% increase in the width of the myoid process and a 20% increase in that of the axonal process during a 12-h light period, compared to the measurements obtained during a 12-h dark period. An increase in the amount of cytoplasm, dilation of ER cisterns, and swelling of the nucleus appeared to cause the enlargement of the myoid parts. Accumulation of synaptic vesicles occurred concurrently with a thickening of the axonal process. These morphological changes presumably represent a phase of the diurnal cycle and current synaptic activity of the short cell. By contrast, the long photorecpetor cell showed neither measurable changes nor any indication of “retinomotor movement”.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00571427
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  • 41
    Digitale Medien
    Digitale Medien
    The paraventricular and posterior recess organs of elasmobranchs: A system of cerebrospinal fluid-contacting neurons containing immunoreactive serotonin and somatostatin (1990)
    Springer
    Cell & tissue research 259 (1990), S. 463-473 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Cerebrospinal fluid-contacting neurons ; Paraventricular organ ; Posterior recess organ ; Somatostatin ; Serotonin ; Ultrastructure ; Immunocytochemistry ; Dogfish,Squalus acanthias skate,Raja radiata (Elasmobranchii)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The paraventricular organ (PVO) and the posterior recess organ (PRO) of two elasmobranch species, the spiny dogfish,Squalus acanthias, and the skate,Raja radiata, were investigated by use of scanning and transmission electron microscopy and immunocytochemistry employing a series of primary antisera. The PVO and PRO contained four types of cerebrospinal fluid (CSF)-contacting neurons. One type was free of secretory granules and projected a dendrite-like process into the ventricle. The other three types were distinguished according to the size of their secretory granules. The ventricular extensions of these cells were filled with secretory granules. By means of immunocytochemistry three types of CSF-contacting neurons were observed in the PVO and PRO. Type I contained only serotonin; type 2 displayed only somatostatin; type 3 was endowed with both serotonin and somatostatin. Type I dominated in the PRO, whereas type 3 was the most frequent in the PVO. The latter cells appear to be the site of origin of a loose tract formed by serotonin- and somatostatinimmunoreactive fibers projecting from the PVO into the neuropil of the PRO. Compact bundles formed exclusively by serotonin fibers were also shown to extend between the PVO and PRO. The basal processes of the CSF-contacting neurons of the PRO penetrated into the underlying neuropil. This neuropil is rich in synapses and can be regarded as an integrative area to which the basal processes of the local CSF-contacting neurons, serotonin and somatostatin fibers from the PVO, and fibers containing immunoreactive thyrotropin-releasing hormone of unknown origin, support a conspicuous input. The present findings indicate that the PVO and PRO of elasmobranchs are functionally integrated structures.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01740772
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  • 42
    Digitale Medien
    Digitale Medien
    Topographical relationships between catecholamine-and neuropeptide-containing fibers in the median eminence of the newt,Triturus alpestris (1990)
    Springer
    Cell & tissue research 259 (1990), S. 561-566 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Median eminence ; Catecholamines ; Neuropeptides ; Immunocytochemistry ; Double labeling ; Ultrastructure ; Triturus alpestris (Urodela)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Dopaminergic and peptidergic nerve fibers were simultaneously demonstrated with a double-labeling technique at the ultrastructural level. The first antibody, raised against tyrosine hydroxylase, was applied during the preembedding phase and visualized with the peroxidase method. The second antibody, raised against one of the peptides met-enkephalin, somatostatin or gonadotropin-releasing hormone (GnRH), was applied to the ultrathin sections and visualized with gold-labeled goat anti-rabbit IgG. The fibers of both categories were present in the zona externa of the median eminence, frequently contacting the basal lamina of the portal vessels. In addition, topographical relationships between different types of nerve fibers were observed in the perivascular areas, although there were no morphological signs of synaptic specializations. Using serial sections, it could be established that one GnRH-fiber contacted both a dopaminergic fiber and a fiber immunoreactive for met-enkephalin. The observations support earlier physiological data concerning the regulation of the hypothalamo-hypophyseal axis, with special emphasis on the release of neurohormones in the median eminence of the newt.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01740784
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  • 43
    Digitale Medien
    Digitale Medien
    Ultrastructural study of crystalloids in Sertoli cells of the three-toed sloth (Bradypus tridactylus) (1990)
    Springer
    Cell & tissue research 259 (1990), S. 599-602 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Crystalloids ; Filaments ; Sertoli cells ; Testis ; Ultrastructure ; Three-toed sloth,Bradypus tridactylus (Edentata)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Crystalloids were found in Sertoli cells of the testis of the three-toed sloth by examination at the lightand electron-microscopic levels. Needle-, or spindle-shaped crystalloids, varying in length, were located in the basal part of the Sertoli cells. They consisted of bundles of filaments each measuring ~ 11 nm in diameter. Several filaments were packed hexagonally to form a bundle. The center-to-center distance between individual filaments of a bundle was ~ 17 nm. Periodical lateral projections emanated from the filaments. Cross sections of crystalloids showed that the projections radiated from each filament in three directions, forming an equilateral triangle with a side length of ~ 15 nm. Scattered polyribosomes were found between and around the bundles.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01740789
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  • 44
    Digitale Medien
    Digitale Medien
    Organization of testicular interstitial tissue of an Australian rodent, the spinifex hopping mouse, Notomys alexis (1990)
    Springer
    Cell & tissue research 260 (1990), S. 469-477 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Testis ; Interstitial tissue ; Leydig cells ; Lymphatics ; Ultrastructure ; Spinifex hopping mouse ; Notomys alexis (Rodentia)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The organization of testicular interstitial tissue of the spinifex hopping mouse, Notomys alexis differs from that of other rodents. It comprises between 10.3% and 17.3% (average 15.0%) of the total testicular volume, and is variable in its organization both at different locations within the testis of the one animal and among different individuals. Abundant, closely packed Leydig cells are usually present; however, in some regions large, thick-walled blood vessels and extensive peritubular lymphatic spaces, often lacking an endothelium adjacent to the Leydig cells, are also prominent. The Leydig cells in contact with the large blood vessels and lymphatics, unlike those in regions where lymph is sparse, are not densely packed and sometimes contain numerous lipid droplets. Ultrastructure of Leydig cells is typical of steroid-producing cells; however, mitochondria are often extremely large, unusual in shape or bizarely arranged in relation to one another. Also electrondense bodies displaying a paracrystalline-like internal structure of parallel, electron-dense filaments arranged in a lattice pattern occur in the cytoplasm of many cells. The significance of these unusual ultrastructural features and the organization of the interstitial tissue remain to be determined conclusively, but may relate to steroid synthesis, secretion and uptake.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00297226
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  • 45
    Digitale Medien
    Digitale Medien
    Immunoreactive atrial natriuretic peptide in the fish heart and blood plasma examined by electron microscopy, immunohistochemistry and radioimmunoassay (1990)
    Springer
    Cell & tissue research 260 (1990), S. 235-247 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Atrial natriuretic peptide ; Heart ; Freshwater fish ; Seawater fish ; Immunohistochemistry ; Ultrastructure ; Radioimmunoassay ; Cyprinus carpio (Teleostei) ; Narke japonica (Elasmobranchii) ; Eptatretus burgeri (Cyclostomata)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The immunoreactivity of atrial natriuretic peptide and ultrastructure of cardiocytes were examined in 5 species each of freshwater and seawater teleosts, as well as in 2 species each of elasmobranchs and cyclostomes. Immunoreactivity was strong in the atria of Cyprinus carpio, Anguilla japonica and Conger myriaster, rather weak in atria of Channa maculata, Lepomis macrochirus, Salmo gairdneri, Oplegnathus fasciatus and Eptatretus burgeri, very weak in atria of Pagrus major, Trachurus japonicus and Triakis scyllia, and not detectable in atria of Hexagrammos otakii, Narke japonica and Lampetra japonica. The immunoreactivity of the atrial cardiocytes was generally stronger in freshwater than seawater fish. Ventricular immunoreactivity was detected only in 7 species, always being weaker than that observed in the atrium. Ultrastructurally, however, secretory granules were found in atria and ventricles of all species examined, being more frequent in the former than the latter. By radioimmunoassay, immunoreactive ANP was detected in the extracts of blood plasma and both atrial and ventricular tissues of all species examined. There were no statistically significant differences in the values between freshwater and seawater species.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00318627
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  • 46
    Digitale Medien
    Digitale Medien
    Ultrastructural changes of liver parenchyma following digitonin-pulse perfusion of rat liver (1990)
    Springer
    Cell & tissue research 261 (1990), S. 423-430 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Hepatocytes ; Liver ; Ultrastructure ; Digitonin perfusion ; Metabolic zonation ; Rat (Wistar)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary It has been shown that pulse perfusion of rat liver with a digitonin-containing medium results in a highly zonated hepatocyte permeabilization, allowing selective sampling of cytosolic constituents from periportal and perivenous (centrolobular) hepatocytes “in situ”. In the present paper we provide an ultrastructural evaluation of the perfusion method. Identical changes in hepatocytes from affected periportal and perivenous zones are found. Affected hepatocytes appear light (electron-lucent) in electron micrographs with a sharp transition to normal hepatocytes. The most conspicuous ultrastructural findings are: (1) transformation of the sinusoidal part of the light hepatocytes, the lipocyte processes and the endothelium of affected zones apparently unifying into a continuous layer dominated by disrupted plasma membranes and 7-nm filaments; (2) deposition of osmiophilic digitonin-cholesterol complexes along the sinusoidal plasma membranes of affected zones; and (3) reduction of the cytoplasmic matrix (cytosol) in the light hepatocytes, a dilation of the mitochondrial intermembrane space with a preserved mitochondrial matrix, and a dilation of cisternae of the granular endoplasmic reticulum. The ultrastructural findings are consistent with marker-enzyme activity measured in eluates from digitonin-perfused livers, except that lysosomes appear intact, apparently contrasting with the observed eluation of amyloglucosidase (Quistorff et al. 1985).
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00313520
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  • 47
    Digitale Medien
    Digitale Medien
    Effect of carbamylcholine on Harderian gland morphology in rats (1990)
    Springer
    Cell & tissue research 261 (1990), S. 451-459 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Harderian gland ; Ultrastructure ; Morphometry ; Carbamylcholine ; Secretion ; Rat (Slc: SD)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary To determine the effect of cholinergic secretagogue on the Harderian gland of rats, several light- and electron-microscopic parameters were morphometrically assessed at different time intervals after carbamylcholine injection. In controls, two types of glandular cells (type A cells having 40–55 large vacuoles per cell profile and type B cells containing 30–38 smaller vacuoles per cell profile) and myoepithelial cells were recognized. At 5 min after injection of carbamylcholine, when rats secreted “bloody tears”, many alveoli showing narrower lumina and exocytotic figures in both types of cells were observed. Some vacuoles, which were covered by thin cytoplasmic sheets, protruded into the alveolar lumina. However, there was no evidence of apocrine or holocrine secretion. At 30 min and 120 min after injection, most of the alveolar lumina were dilated, and a pronounced decrease in the number of vacuoles in the glandular cells was observed. At 300 min after injection, the secretory vacuoles in both cell types reaccumulated. Transitional forms between the two cell types were not observed. The two types of Harderian gland cells can therefore be considered independent populations rather than different secretory stages of the same cell. It appears that the secretory process of the Harderian gland of rat is affected by cholinergic stimulation of the two types of glandular cells and of myoepithelial cells.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00313523
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  • 48
    Digitale Medien
    Digitale Medien
    Effects of visible and ultraviolet radiation on the ultrastructure of zooxanthellae (Symbiodinium sp.) in culture and in situ (1990)
    Springer
    Cell & tissue research 261 (1990), S. 501-508 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Photoadaptation ; Stereology ; Ultrastructure ; Accumulation bodies ; Zooxanthellae ; Symbiodinium sp. ; Protozoa ; Dinoflagellata
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Quantitative ultrastructural studies on the effects of visible and ultraviolet radiation on zooxanthellae in culture and in situ showed an inverse relationship between the volume fraction of chloroplast and irridiance. An independent effect of ultraviolet radiation was detected in cultured zooxanthellae only. The volume fraction of chloroplasts in cultured zooxanthellae and zooxanthellae in situ were the same, while the surface density of thylakoid lamellae relative to chloroplast volume in cultured zooxanthellae was less than in zooxanthellae in situ for all irradiances. Additionally, zooxanthellae in situ showed an effect of ultraviolet radiation on surface density of thylakoid lamellae. The response to different irradiances suggests a limit to photoadaptation by means of changing chloroplast volume, and that changes in thylakoid density are responsible for the continued photoadaptive plasticity observed. Flow cytometry and stereological studies show that the volume fraction of accumulation bodies within zooxanthellae increases with irradiance and ultraviolet radiation. Ultrastructurally, accumulation bodies do not resemble plant peroxisomes or glyoxysomes, while other inclusions observed in this stydy are suggestive of peroxisomes. This evidence suggests that accumulation bodies are not peroxisomes, but does support the previous assumptions concerning their role in autophagic processes.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00313529
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  • 49
    Digitale Medien
    Digitale Medien
    Urinary bladder of rat: fine structure of normal and hypertrophic musculature (1990)
    Springer
    Cell & tissue research 262 (1990), S. 67-79 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Urinary bladder ; Smooth muscle ; Hypertrophy ; Ultrastructure ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The fine structure of the muscle of the urinary bladder in female rats is similar to that of other visceral muscles, although it is arranged in bundles of variable length, cross-section and orientation, forming a meshwork. When distended, the musculature is 100–120 μm thick, with some variation and occasional discontinuity. Extended areas of cell-to-cell apposition with uniform intercellular space occur between muscle cells, whereas attachment plaques for mechanical coupling are less common than in other visceral muscles. There are no gap junctions between muscle cells. Many bundles of microfilaments and small elastic fibres run between the muscle cells. After chronic partial obstruction of the urethra, the bladder enlarges and is about 15 times heavier, but has the same shape as in controls; the growth is mainly accounted for by muscle hypertrophy. The outer surface of the hypertrophic bladder is increased 6-fold over the controls; the muscle is increased 3-fold in thickness, and is more compact. Mitoses are not found, but there is a massive increase in muscle cell size. There is a modest decrease in percentage volume of mitochondria, an increase in sarcoplasmic reticulum, and no appreciable change in the pattern of myofilaments. Gap junctions between hypertrophic muscle cells are virtually absent. Intramuscular nerve fibres and vesicle-containing varicosities appear as common in the hypertrophic muscle as in controls. There is no infiltration of the muscle by connective tissue and no significant occurrence of muscle cell death.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00327747
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  • 50
    Digitale Medien
    Digitale Medien
    Changes in renal morphology and renin secretion in the golden-mantled ground squirrel (Spermophilus lateralis) during activity and hibernation (1990)
    Springer
    Cell & tissue research 262 (1990), S. 99-104 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Hibernation ; Ultrastructure ; Plasma renin activity ; Renal changes ; Spermophilus lateralis (Rodentia)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Chronological changes in renal glomerular morphology and plasma renin activity were investigated during active and hibernating periods in the golden-mantled ground squirrel Spermophilus lateralis. The objective of this study was to determine whether the glomerular endothelium, visceral epithelium (podocytes), basement membrane, mesangial cells, proximal convoluted tubule cells and plasma renin activity exhibit measurable sequential differences between as well as within active and hibernating states at various time points. Limitations in the size of the experimental population prevented an evaluation of changes in these parameters during other important periods such as periodic arousal between hibernation bouts. In this study, glomerular endothelial pore number and epithelial filtration slit number significantly decreased by early hibernation when compared to those during summer activity, and then they increased back toward summer levels by late hibernation. In contrast, podocytic pedicel width along the glomerular basement membrane increased from summer activity to early hibernation, before significantly decreasing again by late hibernation. Mesangial cell and proximal convoluted tubule cell activity appeared increased during hibernation as compared to summer activity, whereas the width of the glomerular basement membrane showed no significant alterations throughout. Plasma renin activity significantly increased during early hibernation and mid-hibernation when compared to summer levels but had decreased by late hibernation toward summer values. The glomerular and plasma renin activity changes observed in this study clearly illustrate the drastic structural and functional adjustments which hibernating species make during torpor and also correlate well with the reported decrease in renal perfusion pressure and urine formation during hibernation. The observed morphological changes during hibernation do not appear to be temperature-dependent, because significant alterations in most of the parameters studied occurred during this period despite the fact that cold-room temperatures were kept constant throughout. The chronological approach to this study and its morphometric evaluation represent a pilot attempt at accurately documenting these changes during two critical states in the hibernator's cycle and may eventually lead to the characterization of these changes during the entire circannual cycle.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00327750
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  • 51
    Digitale Medien
    Digitale Medien
    Organelle loss in the endosymbiont ofGymnodinium acidotum (Dinophyceae) (1990)
    Springer
    Protoplasma 153 (1990), S. 178-185 
    Details
    ISSN: 1615-6102
    Schlagwort(e): Cryptophyceae ; Dinoflagellate ; Dinophyceae ; Endosymbiosis ; Gymnodinium ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The freshwater dinoflagellateGymnodinium acidotum is known to harbor a cryptomonad endosymbiont whose chloroplasts give the organism its blue-green coloration. Every cell examined from a wild population possessed chloroplasts, mitochondria, and other organelles which are of endosymbiotic origin. Transmission electron microscopy and fluorescence microscopy revealed that only 33% of these cells possessed the nucleus of the endosymbiont. The lack of a cryptomonad nucleus in some cells did not appear to affect the cells' ability to photosynthesize or move in response to varying levels of illumination. This represents the first report of a host/endosymbiont relationship in which a significant number of individuals from a given population lack a major endosymbiont organelle.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01354002
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  • 52
    Digitale Medien
    Digitale Medien
    In situ degradation of cellulose fibres by the entodiniomorph rumen ciliatePolyplastron multivesiculatum (1990)
    Springer
    Protoplasma 154 (1990), S. 122-131 
    Details
    ISSN: 1615-6102
    Schlagwort(e): Cellulose degradation ; Ultrastructure ; Rumen ciliate ; Polyplastron multivesiculatum
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The feeding behaviour of the rumen ciliatePolyplastron multivesiculatum has been studied with scanning and transmission electron microscopy. In contrast to other large entodiniomorphs,Polyplastron scarcely attaches to plant substrata such as straw or alfalfa; however, it readily phagocytes cellulose fibres (like epidermal bristles of alfalfa) suspended in the rumen fluid. The different stages of ingestion and intracellular degradation of this particular substrate are described at the ultrastructural level. Engulfment involves active movements of the vestibular lips. The digestion follows a peculiar pattern (“permeative” way): the cellulose substrate is gradually decomposed in situ inside the primary digestive vacuole without large fragmentation or pinching off of small vesicles. Thus degradation products are not stored in secondary vesicular systems as they are for other plant substrates (“cytotic” way). Thus, there is no single or general pattern of cellulosic structures lysis in entodiniomorph rumen ciliates. Rather, several pathways can be observed, probably according to the nature of the ingested plant material.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01539839
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  • 53
    Digitale Medien
    Digitale Medien
    Direct cytoplasm-cytoplasm connection: an unusual host-parasite interaction of the tremelloid mycoparasiteTetragoniomyces uliginosus (1990)
    Springer
    Protoplasma 154 (1990), S. 157-160 
    Details
    ISSN: 1615-6102
    Schlagwort(e): Basidiomycetes ; Cytoplasmic connections ; Host-parasite interaction ; Tetragoniomyces uliginosus ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The cellular interaction ofTetragoniomyces uliginosus andRhizoctonia sp. was restudied by transmission electron microscopy. During the first stages of interaction a body of medium electron density is visible at the center of the haustorial apex in close association with the plasmalemma. A single micropore is produced between the haustorial filament and the host cell. Cytoplasmic connection via the pore always occurred. The pore membrane is continuous with the plasmalemma of both cells. The protoplasts of both the haustorium and the host cell fuse via the micropore. An electron transparent to dense body occlude the pore. Among basidiomycetes, direct connection between the parasite and host protoplasts represents a hitherto unknown type of parasitic interaction.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01539843
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  • 54
    Digitale Medien
    Digitale Medien
    Selenium deficiency in Crustacea (1990)
    Springer
    Protoplasma 154 (1990), S. 25-33 
    Details
    ISSN: 1615-6102
    Schlagwort(e): Selenium deficiency ; Culture medium ; Crustacea ; Daphnia magna ; Ultrastructure ; Cytopathology
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The effect of selenium deprivation onDaphnia magna was examined under controlled rearing conditions in a synthetic culture medium. After three generations, fertility was significantly reduced in deprived (Se−) animals. Growth and mortality of parent daphnids and development of parthenogenetic eggs were not affected during this period. In the fourth generation Se− daphnids rejected parts of their second antennae. At the ultrastructural level antennal muscle tissue was severely affected. Animals deprived of selenium had mitochondria and sarcoplasmic reticulum with myelin-like alterations. Giant lysosomes were present and complete lysis of muscle fibrils was observed in antennal muscle cells. These alterations are characteristic features of peroxidic damage in tissues. This interpretation is consistent with the function of selenium as a constituent of the enzyme glutathione peroxidase which protects cells from peroxidation. Selenium should be included in synthetic culture media for daphnids.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01349532
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  • 55
    Digitale Medien
    Digitale Medien
    Ultrastructure of ascospore delimitation in freeze substituted samples ofAscodesmis nigricans (Pezizales) (1990)
    Springer
    Protoplasma 156 (1990), S. 94-102 
    Details
    ISSN: 1615-6102
    Schlagwort(e): Ascodesmis nigricans ; Ascosporogenesis ; Freeze substitution fixation ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Freeze substitution proved to be a valuable technique for studying the early stages of ascosporogenesis inAscodesmis nigricans. Our observations indicate that the ascus vesicle originated from the ascus plasma membrane. Invaginations of the plasma membrane produced ascus vesicle initials consisting of two closely spaced unit membranes. The appearance of the outer leaflet of each of these membranes was identical to that of the inner leaflet of the ascus plasma membrane. Apparent points of continuity between ascus vesicle initials and the plasma membrane were observed. Ascus vesicle initials accumulated in the ascus cytoplasm near the plasma membrane and then coalesced to form the ascus vesicle, a peripheral, cylinder-like structure consisting of two closely spaced unit membranes that extended from the ascus apex to the ascus base. The ascus vesicle then became invaginated in a number of regions and subsequently gave rise to eight sheet-like segments, or ascosporedelimiting membranes, that encircled uninucleate segments of cytoplasm forming ascospore initials. Like the ascus vesicle, each ascospore-delimiting membrane consisted of two closely spaced unit membranes, the inner of which became the ascospore plasma membrane. The ascospore wall then developed between the spore plasma membrane and the outer membrane. Many details of ascospore maturation were clearly visible in freeze substituted samples.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01666510
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  • 56
    Digitale Medien
    Digitale Medien
    Effects of temperature on cytomorphogenesis and ultrastructure ofMicrasterias denticulata Bréb (1990)
    Springer
    Protoplasma 157 (1990), S. 3-18 
    Details
    ISSN: 1615-6102
    Schlagwort(e): Chilling ; Cytomorphogenesis ; Heat ; “Heat shock granules” ; Micrasterias ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Exposure of growingMicrasterias cells to high (32°–36°C) and low (3°–10°C) temperatures produces changes in morphology that are accompanied by several ultrastructural alterations. Whereas low temperatures essentially cause simplification of cell ornamentation, a variety of cell malformations result from high temperature treatment. These are the loss of cell symmetry leading to markedly aberrant cell shapes and an increase of “main lobes” with reduced degree of differentiation. Preliminary studies indicate that a shift in the distribution of membrane-associated Ca2+ by elevated temperatures probably underlies these abnormal cytomorphogenetic events. Both, low and high temperature cause a reduction in size of the young half cell and affect cytoplasmic streaming. Moreover, nuclear migration is retarded and chloroplast arrangement is influenced by temperature treatment at both ranges. Growth velocity of primary wall responsible for cell shaping is increased at high and slowed down at low temperatures compared to cells grown at 20°C. The main ultrastructural alterations induced by high temperatures are an increase in amount and length of ER cisternae, the appearance of “heat shock granule” aggregations localized in the cytoplasm, a reduced number of ribosomes and polysomes, the presence of oil bodies in growing cells and a varying thickness of the primary wall. Influences of low temperatures on ultrastructure are less pronounced. They are manifested in the formation of large aggregations of ER cisternae slightly differing from those found in untreated cells, a disturbed arrangement of the microtubule system surrounding the nucleus and a decrease of the number of cell wall forming cytoplasmic vesicles. It is thought that most of the temperature effects are due to an influence on membranes probably an alteration of ionic currents and, in addition, a modulation of normal protein synthesis.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01322635
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  • 57
    Digitale Medien
    Digitale Medien
    Ultrastructure of esophageal glands and their secretory granules in the root-knot nematodeMeloidogyne incognita (1990)
    Springer
    Protoplasma 156 (1990), S. 9-18 
    Details
    ISSN: 1615-6102
    Schlagwort(e): Esophageal glands ; Plant-parasitic nematodes ; Secretory granules ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The dorsal and subventral esophageal glands and their secretory granules in the root-knot nematodeMeloidogyne incognita changed during parasitism of plants. The subventral esophageal glands shrank and the dorsal gland enlarged with the onset of parasitism. While secretory granules formed by both types of glands were spherical, membrane-bound, and Golgi derived, the granules differed in morphology and size between the two types of glands. Subventral gland extensions in preparasitic second-stage juveniles were packed with secretory granules which varied in diameter from 700–1,100 nm and had a finely granular matrix. Within the matrix of each subventral gland granule was an electron-transparent core that contained minute spherical vesicles. The size and position of the core varied within different granules. Few granules were present in the dorsal gland extension in preparasitic juveniles. The matrix of dorsal gland secretory granules formed during parasitism was homogeneous and more electron-dense than the matrix of subventral gland granules. Subventral gland secretory granules of parasitic juveniles and adult females appeared degenerate.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01666501
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  • 58
    Digitale Medien
    Digitale Medien
    Polysaccharide and protein secretion by grass microhairs (1990)
    Springer
    Protoplasma 156 (1990), S. 45-56 
    Details
    ISSN: 1615-6102
    Schlagwort(e): Cytochemistry ; Grasses ; Microhairs ; Partitioning membranes ; Polysaccharides ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Secretory activities of bicellular microhairs from grasses belonging to the subfamilies Chloridoideae, Arundinoideae, Panicoideae, and Bambusoideae, and including the “chloridoid”, “panicoid” and “Enneapogon” microhair morphological types, have been investigated. Light microscopic histochemistry indicated that all microhairs studied secrete polysaccharide and protein (or glycoprotein), including those which also secrete salt. Localization of polysaccharide at ultrastructural level using periodic acid-thiocarbohydrazidesilver proteinate staining revealed that in “panicoid type” microhairs dictyosomes are involved in polysaccharide secretion, whereas in the “chloridoid” and “Enneapogon” types “partitioning membranes” seem to be involved instead.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01666505
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  • 59
    Digitale Medien
    Digitale Medien
    Isolation, purification, and characterization of flagellar scales from the green flagellateTetraselmis striata (Prasinophyceae) (1990)
    Springer
    Protoplasma 156 (1990), S. 103-112 
    Details
    ISSN: 1615-6102
    Schlagwort(e): Tetraselmis striata ; Prasinophyceae ; Flagellar scales ; Isolation ; Purification ; Ultrastructure ; Biochemical composition ; 2-keto-sugar acids ; Polypeptide composition
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Flagellar scales from the green flagellateTetraselmis striata (Prasinophyceae) were isolated, purified by isopycnic cesium chloride-gradient and zonal sucrose gradient centrifugation and their structure and biochemical composition investigated. Three types of flagellar scales were purified to more than 90% purity, a fourth type up to 75% purity. In addition to the previously known types of flagellar scales (pentagonal scales, rod-shaped scales, hair-scales), a novel scale type (i.e., the knotted scales) was discovered. New information about the asymmetric structure of the rod-shaped scales is presented and consequently they are renamed “man scales”. Flagellar scales consist mainly of carbohydrate (50–70%), significant amounts of protein (11% of dry weight) were found only in pentagonal scales. The main sugars (90%) of the pentagonal and man scales are the unusual 2-keto-sugar acids 3-deoxy-5-O-methyl-2-octulosonic acid (5 OMeKDO), 3-deoxy-2-heptulosaric acid (DHA), and 3-deoxy-2-octulosonic acid (KDO), the knotted scales contain as major sugars galactose and arabinose in addition to KDO and 5 OMeKDO but lack DHA. 13 major polypeptides were identified in flagellar scales by one-dimensional SDS-PAGE, 11 of these are of high molecular mass (〉116 kDa). While the majority of polypeptides was found associated with pentagonal scales, at least 4 polypeptides were tentatively assigned to the hair-scales and knotted scales.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01666511
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  • 60
    Digitale Medien
    Digitale Medien
    Ultrastructural pathology of the vestibule in patients with acoustic neurinomas: secondarily operated cases after posterior fossa operation (1990)
    Springer
    European archives of oto-rhino-laryngology and head & neck 247 (1990), S. 93-96 
    Details
    ISSN: 1434-4726
    Schlagwort(e): Vestibule ; Acoustic neurinoma ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The vestibular sensory epithelia from two patients with acoustic neurinomas were examined ultrastructurally. Both patients had first undergone posterior fossa operations 8 months and 3 years before residual tumors in the acoustic canals were removed by a secondary translabyrinthine operation. Labyrinthine sensory tissues were also removed for microscopic studies. In case 1, the utricular macula and the lateral and anterior cristae were observed, with all sensory epithelia showing fairly normal findings. Myelinated nerve fibers below the sensory epithelia also appeared normal. In case 2, only the utricular macula could be observed. The sensory epithelium showed severe degeneration, disappearing sensory cells and increasing cytoplasmic filaments of both the sensory cell and the supporting cell. Myelinated nerve fibers below the sensory epithelia were only rarely found.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00183175
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  • 61
    Digitale Medien
    Digitale Medien
    Ultrastructural localization of Ca2+-binding sites in the middle ear mucosa of the rat (1990)
    Springer
    European archives of oto-rhino-laryngology and head & neck 247 (1990), S. 156-160 
    Details
    ISSN: 1434-4726
    Schlagwort(e): Calcium distribution ; Rat middle ear mucosa ; Electron spectroscopic imaging ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Cations were precipitated with potassiumpyroantimonate in the middle ear mucosa of the rat and the distribution of the formed precipitates was studied by electron microscopy. The precipitate density in various cells of the different epithelia of the middle ear mucosa was determined on electron micrographs by counting the number of precipitates per unit area. Electron spectroscopic imaging was also performed to obtain information about the spatial distribution of the precipitates and their elemental composition.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00175968
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  • 62
    Digitale Medien
    Digitale Medien
    Ciliary ultrastructure in a child with Kartagener's syndrome (1990)
    Springer
    European archives of oto-rhino-laryngology and head & neck 248 (1990), S. 49-52 
    Details
    ISSN: 1434-4726
    Schlagwort(e): Kartagener's syndrome ; Immotile cilia ; Ultrastructure ; Tannic acid ; Dynein arm
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Kartagener's syndrome has been characterized by a primary ultrastructural abnormality of the cilia which consequently impairs their movements. We used transmission electron microscopy with tannic acid staining to investigate the fine structure of the cilia from the nasal mucosa of a 7-year-old girl with Kartagener's syndrome. The staining technique employed was useful for visualizing the dynein arms and protofilaments of the microtubules of the cilia. Although 15% of the cilia examined demonstrated microtubular disarrangements, these findings were considered to be acquired changes due to chronic sinusitis. No abnormal ciliary ultrastructures specific to Kartagener's syndrome, such as absence of dynein arms, were detected in this study. In such cases without any abnormal ciliary ultrastructures, it is conceivable that some other unknown factor may be involved in the impaired ciliary movement.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00634781
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  • 63
    Digitale Medien
    Digitale Medien
    Constancy of synaptic ribbon numbers in the retina of the arctic chary, Salvelinus alpinus (1990)
    Springer
    Environmental biology of fishes 27 (1990), S. 131-137 
    Details
    ISSN: 1573-5133
    Schlagwort(e): Diurnal ; Histology ; Photoperiod ; Cones ; Rods ; Ultrastructure ; Fish vision
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Synopsis At high latitudes, such as in Iceland, the daily photoperiod varies from almost continuous darkness in winter to virtually constant light in summer. Previous studies of detailed retinal structure in vertebrates have shown significant daily and annual effects of photoperiod. We sampled arctic charr in Iceland during the summer, including fish that were both light- and dark-adapted, during both day and night. We observed retinomotor responses characteristic of light- and dark-adaptation, but found no difference in the number of synaptic ribbons in the retina. The morpho-physiological changes, appearing as retinomotor responses, are thus not expressed at the synaptic level.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00001942
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  • 64
    Digitale Medien
    Digitale Medien
    Hepatocyte fine structure during maturation and senescence (1990)
    New York, NY : Wiley-Blackwell
    Journal of Electron Microscopy Technique 14 (1990), S. 106-125 
    Details
    ISSN: 0741-0581
    Schlagwort(e): Aging ; Ultrastructure ; Liver volume ; Lysosomes ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Allgemeine Naturwissenschaft
    Notizen: Aging is accompanied by a myriad of changes in cell structure, function, and composition. The fact that much of the information concerning age-related alterations in cellular morphology is qualitative precludes meaningful correlations with biochemical changes in order to enhance data interpretation. The mammalian liver has been subjected to both qualitative and quantitative evaluations of hepatocyte structure as a function of aging, i.e., development, maturation, and senescence. Although these data are characterized by considerable variability and, in some instances, blatant contradictions, there exists sufficient agreement in several parameters to permit a consensus in the inbred rat model. Certainly the volume of individual hepatocytes increases with age, and many of the organelle compartments reflect this change. While old rats exhibit a high incidence of polyploidy, there is no definitive evidence to demonstrate a concomitant increase in the binuclear hepatocyte index. Several specific hepatocellular organelles undergo changes in their relative volume or surface area that appear to correlate with functional alterations. The volume density of the lysosomal compartment enlarges significantly during senescence and is accompanied by increased activities of several constituent hydrolases. The hepatic concentration of smooth-surfaced endoplasmic reticulum declines markedly with aging, as does the yield of liver microsomes and the activities of several microsomal enzymes, e.g., mono-oxygenases and glucose-6-phosphatase. However, the responses of the majority of hepatocyte organelles to aging is varied and inconsistent based on the limited data currently available.
    Zusätzliches Material: 20 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jemt.1060140205
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  • 65
    Digitale Medien
    Digitale Medien
    Fine structure of hepatocytes during the etiology of several common pathologies (1990)
    New York, NY : Wiley-Blackwell
    Journal of Electron Microscopy Technique 14 (1990), S. 179-207 
    Details
    ISSN: 0741-0581
    Schlagwort(e): Ultrastructure ; Liver disease ; Hepatitis ; Alcoholic injury ; Storage diseases ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Allgemeine Naturwissenschaft
    Notizen: Hepatocytes respond to injury by a few basic pathological reactions that are reflected in cell death, different types of degeneration, regeneration, or tumorous transformation. At the ultrastructural level, alterations of cell organelles can be observed in different combinations as a result of the injury, depending on the etiological agent(s) or pathological conditions developed. Nuclear bodies, dilation and fragmentation of rough endoplasmic reticulum (rer), swelling of mitochondria, and an increased number of lysosomes occur during acute viral hepatitis. The core and surface components of the hepatitis B virus can be localized in the liver cells in chronic hepatitis and in carriers. Close contact of hepatocytic and lymphocytic cell membranes were observed in chronic active hepatitis. Hepatocytes surrounded by an increased amount of collagen fibers are characteristic of cirrhosis. Loosely arranged, fine fibrils or condensed forms of Mallory bodies are pathognomic for alcoholic injury. A wide spectrum of alterations are noted after drug treatment: the proliferation of smooth endoplasmic reticulum (ser) as an adaptive phenomenon, focal or complete necrosis of the cell, inflammation, and the like. The fine structural analysis of hepatocytic inclusions in storage diseases has a differential diagnostic value. The storage of copper and other elements can be measured by x-ray microanalysis. The study of the hepatocytic differentiation in liver tumors is highly important in establishing the diagnosis and in proving the hepatocytic origin of the tumor.
    Zusätzliches Material: 24 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jemt.1060140302
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  • 66
    Digitale Medien
    Digitale Medien
    A review of echinoderm oogenesis (1990)
    New York, NY : Wiley-Blackwell
    Journal of Electron Microscopy Technique 16 (1990), S. 93-114 
    Details
    ISSN: 0741-0581
    Schlagwort(e): Ultrastructure ; Biochemistry ; Maturation ; Comparative ; Oocytes ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Allgemeine Naturwissenschaft
    Notizen: This review of the anatomical, histological, biochemical, and molecular biological literature on echinoderm oogenesis includes the entire developmental history of oocytes; from their inception to the time they become ova. This is done from a comparative perspective, with reference to members of the five extant echinoderm classes; crinoids, holothurians, asteroids, ophiuroids, and echinoids. I describe the anatomy and fine structure of the echinoderm ovary, with emphasis on both the cellular relationships of the germ line cells to the somatic cells of the inner epithelium, and on the neuromuscular systems. I review the literature on the growth of oogonia into fully formed oocytes, including the process of vitellogenesis, presenting an ultrastructural analysis of the organelles and extracellular structures found in fully formed echinoderm oocytes. Echinoderm oocyte maturation is reviewed and a description of the ultrastructural, biochemical and molecular biological changes thought to occur during this process is presented. Finally, I discuss oocyte ovulation, the severing of cellular connections between the oocyte and its surrounding somatic epithelial cells.
    Zusätzliches Material: 16 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jemt.1060160203
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  • 67
    Digitale Medien
    Digitale Medien
    Transformation of the amphibian oocyte into the egg: Structural and biochemical events (1990)
    New York, NY : Wiley-Blackwell
    Journal of Electron Microscopy Technique 16 (1990), S. 202-234 
    Details
    ISSN: 0741-0581
    Schlagwort(e): Xenopus ; Meiosis ; Ultrastructure ; Intracellular signals ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Allgemeine Naturwissenschaft
    Notizen: Amphibian oocytes, arrested in prophase I, are stimulated to progress to metaphase II by progesterone. This process is referred to as meiotic maturation and transforms the oocyte, which cannot support the early events of embryogenesis, into the egg, which can. Meiotic maturation entails global reorganization of cell ultrastructure: In the cell cortex, the plasma membrane flattens and the cortical granules undergo redistribution. In the cell periphery, the annulate lamellae disassemble and the mitochondria become dispersed. In the cell interior, the germinal vesicle becomes disassembled and the meiotic spindles form. Marked changes in the cytoskeleton and mRNA distribution also occur throughout the cell. All of these events are temporally correlated with intracellular signalling events: Fluctuations in cAMP levels, changes in pH, phosphorylation and dephosphorylation, and ion flux changes. Evidence suggests that specific intracellular signals are responsible for specific reorganizations of ultrastructure and mRNA distribution.
    Zusätzliches Material: 18 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jemt.1060160303
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  • 68
    Digitale Medien
    Digitale Medien
    Monoamine synaptic structure and localization in the central nervous system (1990)
    New York, NY : Wiley-Blackwell
    Journal of Electron Microscopy Technique 15 (1990), S. 20-33 
    Details
    ISSN: 0741-0581
    Schlagwort(e): Catecholamines ; Ultrastructure ; Synaptic terminals ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Allgemeine Naturwissenschaft
    Notizen: The monoamines dopamine, noradrenaline, adrenaline, and serotonin as well as the diamine histamine have a widespread distribution in the central nervous system within synaptic terminals and nonsynaptic varicosities. In certain regions of the central nervous system the monoamines are contained in varicosities that have no synaptic specialization associated with them, suggesting a possible neuromodulatory role for some of the monoamines. The majority of monoamine labelled structures are synaptic terminals which are characterized by the presence of small, clear vesicles (40-60 nm) and large, granular vesicles (70-120 nm) within the terminal. A third population of vesicles - small, granular vesicles - which are visible only after histochemical staining, are probably the equivalent of the small, clear vesicles present after either autoradiographic or immunohistochemical labelling. Most monoamine containing terminals contact dendrites and dendritic spines and, less frequently, neuronal somata and other axons. Both asymmetrical and symmetrical membrane specializations are associated with monoaminergic terminals; however, asymmetrical contacts are the most frequent type found. These ultrastructural results indicate that monoamine containing terminals and varicosities in general share many common morphological features, but still have diverse functions.
    Zusätzliches Material: 13 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jemt.1060150104
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  • 69
    Digitale Medien
    Digitale Medien
    Phaseolus vulgaris leucoagglutinin (PHA-L): A neuroanatomical tracer for electron microscopic analysis of synaptic circuitry in the cat's dorsal lateral geniculate nucleus (1990)
    New York, NY : Wiley-Blackwell
    Journal of Electron Microscopy Technique 15 (1990), S. 352-368 
    Details
    ISSN: 0741-0581
    Schlagwort(e): Lectins ; Ultrastructure ; Visual system ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Allgemeine Naturwissenschaft
    Notizen: Phaseolus vulgaris leucoagglutinin (PHA-L) is a plant lectin that is anterogradely transported by neurons in the central nervous system. PHA-L is selectively taken up by cells at iontophoretic injection sites and, when immunohistochemically demonstrated, labels individual neurons completely, including their dendrites, axons, and terminal boutons. PHA-L is generally not taken up by fibers passing through the injection site and, because it produces a Golgi-like staining of even very fine axons over long distances, it is sometimes possible to light microscopically reconstruct individual neurons and their entire axon terminal arbors. When prepared for electron microscopy, the PHA-L-labeled terminals are densely and completely stained, allowing their synaptic relationships to be defined. These properties make PHA-L advantageous for studying the patterns of projection and the modes of termination of select groups of neurons in their target nuclei.We used PHA-L to study the extraretinal innervation of the cat's dorsal lateral geniculate nucleus, a thalamic visual center. Although much is known about the retinal contribution to geniculate synaptic circuitry, relatively little is known about other sources of innervation, even though these provide the majority of synaptic terminals in the nucleus (Guillery: Z. Zellforsch., 96:1-38, 39-48, 1969; Wilson et al.: Proc. R. Soc. Lond. [Biol.], 221:441-436, 1984). We used both light and electron microscopy to describe synaptic circuitry from three extraretinal sources of projections to the lateral geniculate nucleus: the visual cortex, the perigeniculate nucleus, and the parabrachial region of the brainstem. Cortical terminals labeled with PHA-L were small and formed asymmetrical synaptic contacts onto small-caliber dendrites of geniculate neurons. Peri-geniculate terminals formed symmetrical synaptic contacts primarily onto small-caliber dendrites, but some synapses were also formed onto the proximal, retinorecipient portions of geniculate dendrites. Parabrachial terminals synaptically contacted the retinorecipient portions of dendritic appendages and shafts, small-caliber dendrites, and the specialized dendritic (F2) terminals of geniculate interneurons. The symmetry of the parabrachial synaptic contacts was variable and was related to the postsynaptic target. Contacts onto dendritic appendages were asymmetrical while those onto dendritic shafts and F2 terminals were symmetrical. Our data suggest that in unlabeled material these brainstem terminals would be difficult to distinguish from cortical or perigeniculate profiles. The positioning of the parabrachial input onto the retinorecipient portions of geniculate dendrites indicates that this projection is well situated to control primary retinal transmission through the nucleus, while the location of most cortical and perigeniculate innervations implicates them in secondary feedback interactions or other aspects of geniculate function.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jemt.1060150405
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  • 70
    Digitale Medien
    Digitale Medien
    Renewal of the intestinal epithelium: New aspects as indicated by recent ultrastructural observations (1990)
    New York, NY : Wiley-Blackwell
    Journal of Electron Microscopy Technique 16 (1990), S. 2-14 
    Details
    ISSN: 0741-0581
    Schlagwort(e): Intestine ; Epithelium ; Mucous cells ; Nucleolus ; Cell kinetics ; Ultrastructure ; Protein synthesis ; RNA synthesis ; Stem cells ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Allgemeine Naturwissenschaft
    Notizen: This article is a summary of our work of several years on the renewal of the intestinal epithelium. A combination of ultrastructural, radioautographic, and light microscopic analyses was carried out using normal tissue and tissue affected by inhibitors of RNA and protein synthesis. Measuring protein synthesis by 3H-leucine radioautography showed that the life span of the columnar (absorptive) cells in the rat small intestine was divisible into two main phases: differentiation (from stem to functional cell) and maturation (from functional to extruding cell), each phase and its subdivisions being well defined morphologically. Differentiation involved a linear rise in the rate of protein synthesis per cell and showed at the same time heterochromatinization and silencing of RNA transcription. Data from various experiments indicated that the cells functioned from stored information (RNA), part of which came from the nucleolus, which underwent marked and characteristic ultrastructural changes. Although transcription from rDNA ceased, the nucleolus released its ribosomal material, which added to the existing protein synthesis, presumably by recruiting excess stored mRNAs. Maturation involved a nearly linear decrease of the rate of protein synthesis per cell to a characteristic low value at which extrusion took place. A gradual exhaustion of the stored RNA was indicated to be the key factor in this decrease. Ultrastructurally, maturation was associated with a gradually increasing vesiculation of rER and Golgi. The results thus imply a regulatory role of cellular protein synthesis level in renewal. This would be an epigenetic response after the genes are silenced. The nucleolus seems to play a central role in this process, and this in turn is reflected in its characteristic ultrastructural changes. The work also included new observations on the epithelium of the rat ascending colon describing a hitherto unrecognized deep crypt mucus-secretory (“DCS”) cell which is a nongoblet mature cell type apparently arising from midcrypt mitoses. In between the DCS cells, occasional slender columnar cells were seen which displayed the ultrastructural features of stem cells. These were probably reserve stem cells. We also observed nongoblet deep crypt mucous cells in the human right colon although fewer in number than in the rat. Nucleolar regulation and the presence of reserve stem cells represent new dimensions in our understanding of renewal. Electron microscopy is an essential tool in this investigation.
    Zusätzliches Material: 15 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jemt.1060160103
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  • 71
    Digitale Medien
    Digitale Medien
    Cholinergic synapses in the central nervous system: Studies of the immunocytochemical localization of choline acetyltransferase (1990)
    New York, NY : Wiley-Blackwell
    Journal of Electron Microscopy Technique 15 (1990), S. 2-19 
    Details
    ISSN: 0741-0581
    Schlagwort(e): Acetylcholine ; Cholinergic fibers ; Electron microscopy ; Ultrastructure ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Allgemeine Naturwissenschaft
    Notizen: Cholinergic synapses can be identified in immunocytochemical preparations by the use of monoclonal antibodies and specific antisera to choline acetyltransferase (ChAT), the synthesizing enzyme for acetylcholine (ACh) and a specific marker for cholinergic neurons. Electron microscopic studies demonstrate that the fibers and varicosities observed in light microscopic preparations of many brain regions are small-diameter unmyelinated axons and vesicle-containing boutons. The labeled boutons generally contain clear vesicles and one or more mitochondrial profiles. Many of these boutons form synaptic contacts, and the synapses are frequently of the symmetric type, displaying thin postsynaptic densities and relatively short contact zones. However, ChAT-labeled synapses with asymmetric junctions are also observed, and their frequency varies among different brain regions. Unlabeled dendritic shafts are the most common postsynaptic elements in virtually all regions examined although other neuronal elements, including dendritic spines and neuronal somata, also receive some cholinergic innervation. ChAT-labeled boutons form synaptic contacts with several different types of unlabeled neurons within the same brain region. Such findings are consistent with a generally diffuse pattern of cholinergic innervation in many parts of the central nervous system. Despite many similarities in the characteristics of ChAT-labeled synapses, there appears to be some heterogeneity in the cholinergic innervation within as well as among brain regions. Differences are observed in the sizes of ChAT-immunoreactive boutons, the types of synaptic contacts, and the predominant postsynaptic elements. Thus, the cholinergic system presents interesting challenges for future studies of the morphological organization and related function of cholinergic synapses.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jemt.1060150103
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  • 72
    Digitale Medien
    Digitale Medien
    Development of spiral ganglion cells in mammalian cochlea (1990)
    New York, NY : Wiley-Blackwell
    Journal of Electron Microscopy Technique 15 (1990), S. 144-154 
    Details
    ISSN: 0741-0581
    Schlagwort(e): Ultrastructure ; Spiral ganglion ; Ontogenesis ; Myelination ; TII neurons ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Allgemeine Naturwissenschaft
    Notizen: The development of the spiral ganglion in the cat, the rat, and the mouse was studied by electron microscopy, from fetal stages in the cat and from birth in the rodent. In the earliest stages, a single population of ganglion cells is present. Immature spiral ganglion neurons possess small perisomatic processes that seem to disappear with development, before the myelination ganglion cells are surrounded by one or two layers of Schwann cell processes. With maturation, the Schwann process increases in number around the perikaryon and its processes, which leads to the onset of myelination. The onset of myelination of the cell body processes is asynchronous. The perikaryon may be delayed in myelination by several days. Moreover, ganglion neurons from a given region of the cochlea do not myelinate simultaneously. The differentiation of two types of fibers in the intraganglionic spiral bundle and the first appearance of TII neurons occurs around birth in the cat and a few days after birth for the rat and the mouse. The distinction of TII cells is possible due to characteristic accumulation of neurofilamentous structures in the cytoplasm.
    Zusätzliches Material: 21 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jemt.1060150206
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  • 73
    Digitale Medien
    Digitale Medien
    Ultrastructural correlates of meiotic maturation in mammalian oocytes (1990)
    New York, NY : Wiley-Blackwell
    Journal of Electron Microscopy Technique 16 (1990), S. 257-280 
    Details
    ISSN: 0741-0581
    Schlagwort(e): Oocyte ; Maturation ; Ultrastructure ; Gap junction ; Cortex ; Mammal ; Granulosa ; Actin ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Allgemeine Naturwissenschaft
    Notizen: Immature mammalian oocytes reside in ovarian follicles with junctionally coupled granulosa cells. When released from a currently undefined meiotic arresting influence, these oocytes resume meiosis to progress from late diplotene (germinal vesicle stage) through the first meiotic division to metaphase II. Oocytes remain at metaphase II until fertilization activates them to complete meiosis. This review summarizes ultrastructural events that occur during meiotic maturation in mammals. Developmental correlates that promise a clearer understanding of regulatory mechanisms operating to control maturation are emphasized. By use of TEM of thin sections, freeze-fracture analysis, and replicated oocyte cortical patches, we demonstrate stage-specific changes in the oocyte nucleus, reorganization of cytoplasmic organelles, correlations between oocyte maturational commitment and the junctional integrity of associated granulosa cells, and definition of the components comprising the oocyte cortical cytoplasm.
    Zusätzliches Material: 17 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jemt.1060160402
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  • 74
    Digitale Medien
    Digitale Medien
    Licht- und elektronenmikroskopische Untersuchungen an den peritubulären Zellen des Schweinehodens während der postnatalen Entwicklung (1973)
    Springer
    Anatomy and embryology 143 (1973), S. 49-64 
    Details
    ISSN: 1432-0568
    Schlagwort(e): Testicular peritubular cells ; Boar ; Postnatal development ; Ultrastructure ; Contractility
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Die Membrana propria der Hodentubuli des Schweines zeigt einen deutlichen Schichtenbau: Auf die Basalmembran des Tubulusepithels (a) folgen eine nicht-celluläre Lage mit Kollagenfibrillen (b), die von einer inneren (c) und einer äußeren (e) Basalmembran umhüllten peritubulären Zellen (d) und dann das intertubuläre lockere Bindegewebe (f). Die ausdifferenzierten peritubulären Zellen haben viele morphologische Merkmale mit glatten Muskelzellen gemeinsam. So besitzen sie Plasmalemmeinbuchtungen in Form pinocytotischer Bläschen sowie eine große Anzahl von Filamenten mit einem Durchmesser von 60–70 Å, welche über elektronendichte Strukturen an der Innenseite des Plasmalemms befestigt sind. Ein Golgi-Apparat, rauhes endoplasmatisches Reticulum, Mitochondrien und Mikrotubuli bevorzugen eine kernnahe Position. Im Gegensatz zu den Verhältnissen bei anderen Species sind viele charakteristische Eigenschaften der peritubulären Zellen schon vor der Pubertät ausgebildet. Die Filamente können bereits am 4. Tag als feines Netzwerk beobachtet werden, sie erfahren am 25. Tag eine starke Vermehrung und sind von nun an regelmäßig orientiert. Auch andere Befunde sprechen dafür, daß die peritubulären Zellen um den 25. Tag eine gesteigerte Aktivität entfalten. Die histochemisch nachgewiesenen Konzentrationen von alkalischer Phosphatase, Adenosintriphosphatase und Glucose-6-phosphatase erreichen zu diesem Zeitpunkt die hohen Werte, die auch für die weitere Entwicklungsphase und die ausdifferenzierten peritubulären Zellen typisch sind. Pinocytotische Bläschen erscheinen in größerer Anzahl ab dem 97. Tag. Mit dem 140. Tag sind die peritubulären Zellen morphologisch ausdiffrenziert.
    Notizen: Summary The boundary tissue of the porcine testicular seminiferous tubule (membrana propria) exhibits a distinct stratification: the basement lamina of the tubular epithelium (a) is followed by a non-cellular layer with collagen fibrils (b), the peritubular cells (d) with an inner (c) and outer (e) basement lamina and finally the intertubular loose connective tissue (f). Fully developed peritubular cells have many morphological features in common with smooth muscle cells, for instance inpocketings of the plasmalemma (pinocytotic vesicles) and a great number of filaments measuring 60–70 Å in diameter. These filaments are fixed at the inner side of the plasmalemma by means of electron-dense structures. The Golgi apparatus, rough endoplasmic reticulum, mitochondria and microtubules prefer a juxtanuclear position. In contrast that is seen in other species the porcine peritubular cells develop many of their characteristic features before puberty. In samples of the 4th day a fine network of filaments is already visible within the cytoplasm. These filaments are strongly augmented at the 25th day, and from now on they are arranged in a regular fashion. Other findings, also, underline an increased activity of the peritubular cells around day 25. At that time the concentrations of histochemically demonstrated alkaline phosphatase, adenosine triphosphatase and glucose-6-phosphatase reach the high levels typical for the stages of further development and the fully differentiated cells. Pinocytotic vesicles appear in great numbers from day 97. At the 140th day the morphology of the porcine peritubular cell is completely developed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00519910
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  • 75
    Digitale Medien
    Digitale Medien
    The early development of the median thyroid gland of the mouse (1973)
    Springer
    Anatomy and embryology 139 (1973), S. 319-336 
    Details
    ISSN: 1432-0568
    Schlagwort(e): Fetal thyroid ; Microfilaments ; Lysosomes ; Acid phosphatase ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The mesobranchial area and the median thyroid anlage of embryonic albino mice were investigated from the somite stage 4 to 40 (81/2–10 days of gestation). In stage I (5–25 somites), there is an unequal growth and differentiation of the epithelium in the floor of the pharynx, whereby a mesobranchial area with a stratified or pseudostratified epithelium is formed. This area is distinct from the remaining pharyngeal epithelium, among other things by an apical microfilament system in the superficial epithelial cells. It is found just basal to a row of plump cytoplasmic protrusions, which extend into the lumen of the pharynx. In stage II (26–40 somites), the cranial part (median thyroid anlage) of the mesobranchial area thickens in relation to the caudal part and grows down into the underlying mesenchyme. The filament system is concentrated in the superficial cell layer of the median thyroid anlage at the beginning of stage II and disappears during downgrowth. In both stages, but most pronounced in stage II, there is a population of 0.1–5 μ intracellular bodies, which occasionally contain the remains of organelles. The larger bodies, which often contain the remains of nuclei, are usually found peripherally while the smaller ones are more evenly distributed. Acid phosphatase can often be demonstrated histochemically in small bodies, while larger bodies are usually without reaction. Cells with pycnotic nuclei and/or degenerated cytoplasmic components are regularly found. Acid phosphatase can also be demonstrated in Golgi complexes and surrounding vesicles. Basal to the epithelium, bodies are occasionally found which may possibly have been extruded from that tissue.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00519971
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  • 76
    Digitale Medien
    Digitale Medien
    Uterine stromal morphology of the spayed, virgin rat when prepared with progesterone and oestrogen for implantation (1973)
    Springer
    Anatomy and embryology 141 (1973), S. 161-169 
    Details
    ISSN: 1432-0568
    Schlagwort(e): Rat ; Uterus ; Stroma ; Ultrastructure ; Sex steroids
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The effect of progesterone and oestrogen on the central uterine stroma has been examined in order to analyze what changes occur when the uterus is hormonally prepared for implantation. Both progesterone and oestrogen, when given separately, cause nucleolar enlargement and growth of the granular endoplasmic reticulum. However, after progesterone treatment the nuclei are large and spherical whereas they are spindle-shaped after oestrogen treatment. When oestrogen is administered to the progesterone-treated rat little change occurs in the stromal morphology. There is little morphological support to the view that oestrogen acts on the stroma to increase endometrial sensitivity. Further, progesterone seems to stimulate the synthesis of RNA and of cellular protein only in the stromal cell while oestrogen has a similar effect in all cell types of the uterus.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00519883
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  • 77
    Digitale Medien
    Digitale Medien
    Ultrastructural aspects of the preattached pig embryo: Cleavage and early blastocyst stages (1973)
    Springer
    Anatomy and embryology 143 (1973), S. 95-114 
    Details
    ISSN: 1432-0568
    Schlagwort(e): Cleavage stages ; Blastocyst ; Pig ; Nucleus ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Ultrastructural observations of morphological changes in nuclei and cytoplasm of pig embryos during cleavage and early blastocyst stages are presented. Compact nuclear bodies (nucleosphaeridies) are demonstrable in the cleavage stages, and occasionally in the inner cell mass of blastocysts. The transformation of nucleosphaeridies leading to the formation of a peripheral network are usually found at the eight-cell stage. In morula, nucleoli make their first appearance as clearly distinguishable morphological entities. A marked disorganization of nuclear envelope is observed near to the cytoplasmic annulate lamellae (CAL) indicating a possible process of transformation of the former to the latter. During premorula stages cytoplasmic organelles (Golgi complex, endoplasmic reticulum, and CAL) are predominantly concentrated around the nucleus. CAL associated with fibrillogranular material similar to the material of the nucleoplasm occur in juxtanuclear positions. In the two-cell stage, degenerating paternal mitochondria are observed. In the morula the number of spherical mitochondria fell while that of elongated mitochondria increase. The trophoblast cells of the blastocyst stage contain cytoplasmic microfilaments which are closely associated with cell organelles, particularly the desmonsomes. Structurally changed mitochondria near the yolk globules and inclusion bodies of various morphology are found. A basal lamina is discernible parallel to the trophoblast layer facing the blastocoel. The observations are discussed in relation to physiological phenomena known to occur during embryogenesis.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00519913
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  • 78
    Digitale Medien
    Digitale Medien
    Ultrastructure of a sacrococcygeal chordoma (1973)
    Springer
    Acta neuropathologica 25 (1973), S. 27-35 
    Details
    ISSN: 1432-0533
    Schlagwort(e): Ultrastructure ; Chordoma ; Sacrococcygeal
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The ultrastructure of a sacrococcygeal chordoma is presented. The cells vary in their size and electron density but are thought to have a common origin. The nuclei presented prominent nucleoli and intranuclear bodies. Centrioles were seen in some of the cells. The rough endoplasmic reticulum was prominent and in most cells was very distended and corresponded to the intracellular vacuoles of light microscopy. The contents of the rough endoplasmic reticulum and the abundant extracellular substance were similar.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00686855
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  • 79
    Digitale Medien
    Digitale Medien
    Ultrastructure of herpes simplex virus infection of the nervous system of mice (1973)
    Springer
    Acta neuropathologica 26 (1973), S. 285-299 
    Details
    ISSN: 1432-0533
    Schlagwort(e): Herpes simplex Virus ; Ultrastructure ; Viral Infection ; Virus-Host Interaction ; Nervous System
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The nervous system and small intestine of mice infected with herpes simplex virus were examined by electron microscopy from the viewpoint of virus-host interaction. The host cells examined included the neuron, astrocyte, oligodendrocyte, and Schwann cell. The susceptibility of the latter was not less than that of the neuron. The endothelial cell, perineural fibrocyte and smooth muscle cell were also host cells. Replication of herpes virus in the nervous system was proven to be identical to that occurringin vitro; initial reproduction of nucleocapsids in the nucleus and subsequent maturation at the nuclear membrane with envelope formation, followed by discharge into the cytoplasmic reticular cavities and finally release from the host cell. Inconsistency in the distribution of virus particles and viral antigen was chiefly concerned with the host cell nucleus and the glial cytoplasm. Herpes virions, though few, were identified in the axons of peripheral nerves, and in the periaxonal space of myelinated fibres in the brain and the nerve ganglia. Virions were present in tiny vesicles in the perikarya or as naked particles. In the distal parts of peripheral nerve, there was marked dissociation in the amount of virions between Schwann cells and the axon. The significance of the endoneural space and the axon in the neural speread of infection is discussed briefly.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00688077
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  • 80
    Digitale Medien
    Digitale Medien
    Electron microscopic study of the muscle changes in diabetic amyotrophy (1973)
    Springer
    Acta neuropathologica 24 (1973), S. 331-339 
    Details
    ISSN: 1432-0533
    Schlagwort(e): Diabetic Amyotrophy ; Muscle Biopsy ; Ultrastructure ; Type II Fibre Atrophy ; Partial Denervation ; Neurogenic Atrophy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Seven cases of diabetic amyotrophy were investigated by histochemistry and electron microscopy of biopsied muscles. Type II fibre atrophy of various grades was observed in the proximal atrophic muscles. Various changes of Z-band were observed in type II atrophic muscle fibres. In addition, mitochondrial changes, accumulation of glycogen, thickening of the capillary basement membrane and changes in the intramuscular nerves were also observed, both in the proximal and distal muscles. Some impaired motoneuron innervation of proximal muscles as well as distal muscles in a poorly controlled diabetic condition is suspected in “diabetic amyotrophy”.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00685588
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  • 81
    Digitale Medien
    Digitale Medien
    Electron microscopic visualization of proteoglycans and collagen in bovine costal cartilage (1973)
    Springer
    Calcified tissue international 13 (1973), S. 83-92 
    Details
    ISSN: 1432-0827
    Schlagwort(e): Proteoglycan ; Collagen ; Cartilage ; Electron Microscopy ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Beschreibung / Inhaltsverzeichnis: Résumé L'élimination de protéoglycans solubles de coupes de cartilage costal de boeuf, par extraction dans une solution de 4M d'hydrochlorure de guanidinium, permet de mettre en évidence des quantités abondantes de collagène dispersé et désagrégé dans la matrice. Les protéoglycanes, résistants à l'extraction, sont visibles sous forme de granules concentrés dans les régions périlacunaires. Les granulations plus importants des protéoglycanes semblent venir du chondrocyte. Dans la matrice, éloignée des chondrocytes, ces granules deviennent plus étroites. Un composant non granulaire “amorphe” masque les fibres de collagène, de telle sorte qu'elles sont difficilement visibles dans le cartilage intact.
    Kurzfassung: Zusammenfassung Die löslichen Proteoglycane wurden mittels Extraktion in 4 M Guanidinhydrochlorid aus Rippenknorpelschnitten des Rindes entfernt. Dies erlaubte die Sichtbarmachung von großen Mengen von verstreuten und auseinandergerissenen Collagen in der Matrix. Die Protoglycane, welche sich nicht extrahieren lassen, erscheinen als kleine, in den perilacunären Regionen konzentrierte Körnchen. Die großen Proteoglycan-Körner scheinen in den Chondrocyten zu entstehen. Sobald sie sich in die Matrix, außerhalb der Chondrocyten, verlagern, werden die Körner kleiner. Ein nicht-granulärer, „amorpher” Bestandteil verhüllt die Collagenfasern, so daß diese im intakten Knorpel nicht deutlich gesehen werden können.
    Notizen: Abstract Removal of the soluble proteoglycans from slices of bovine costal cartilage by extraction in 4 M guanidinium hydrochloride permitted the visualization of abundant amounts of dispersed and disaggregated collagen in the matrix. Proteoglycans which are resistant to extraction are seen as small granules which are concentrated in the perilacunar regions. Large proteoglycan granules appear to originate in the chondrocyte. As they come to occupy positions in the matrix distant from the chondrocyte, the granules become smaller. A non-granular, “amorphous” component masks the collagen fibers so that they cannot be readily seen in the intact cartilage.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02015399
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  • 82
    Digitale Medien
    Digitale Medien
    Ultrastructural analysis of phospholipase a induced changes in membranes of synaptic regions in rat motor cortex (1973)
    Springer
    Experimental brain research 16 (1973), S. 400-409 
    Details
    ISSN: 1432-1106
    Schlagwort(e): Ultrastructure ; Synapses ; Brain cortex ; Phospholipase A ; Membranes
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The effect of purified Naja nigricollis phospholipase A on slices from motor cortex from rat brain was analysed at an ultrastructural level. Samples stabilized directly with glutaraldehyde were compared with samples incubated in buffer with or without enzyme. Plasma membranes of nerve terminals, synaptic contact regions and synaptic vesicles were the main parameters studied. As judged by the electron microscopic technique the synaptic areas show a high resistance to the enzyme treatment. The intercellular space of the synaptic cleft seems unaltered. At the highest concentrations of the enzyme an increased density is noticed at the presynaptic part of the membrane. The extracellular space widens and nerve terminals and mitochondria become distended with increasing enzyme concentrations. The membranes all through the tissue appear ruptured to small pieces and at the highest enzyme concentrations used, altered in their structural organization. Quantitative analysis shows that the number of synaptic vesicles per unit surface area decreases, while ruptures of the plasma membranes of nerve terminals increase in number with increasing enzyme concentrations.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00233431
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  • 83
    Digitale Medien
    Digitale Medien
    The ultrastructure of the sinuatrial ring bundle and of the caudal extension of the sinus node in the right atrium of the rabbit heart (1973)
    Springer
    Cell & tissue research 138 (1973), S. 97-112 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Heart ; Rabbit ; Sinuatrial node ; Sinuatrial ring bundle ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The cells of the sinuatrial ring bundle are smaller than the ordinary myocardial cells; they have a regular outline and a large content of myofibrils exhibiting distinct H-bands and M-lines. Rudimentary T-tubules are found. The cells are connected by frequent nexus junctions, desmosomes and regions of interfibrillar contact, both on the well developed intercalated discs and at the periphery of the cells. The cells in the cauda of the sinus node, which extends alongside the crista terminalis together with the right branch of the sinuatrial ring bundle, are irregularly outlined and have a highly variable diameter (1–10 μm). They occur in clusters of closely packed cells. The content of myofibrils is sparse and the fibrils exhibit no M-lines and only weak H-bands. No T-tubules are found. The cells are not connected by intercalated discs and no nexus junctions are found. Both tissues contain unmyelinated nerves and nerve fibres. Varicosities with mitochondria and vesicles are found in close apposition to the muscle cells.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00307081
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  • 84
    Digitale Medien
    Digitale Medien
    The hypothalamo-hypophysial system in acipenseridae (1973)
    Springer
    Cell & tissue research 136 (1973), S. 461-477 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Neurohypophysis ; Acipenseridae ; Neurosecretion ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The neurohypophysis of sexually mature male and female Acipenser güldenstädti Brandt and Acipenser stellatus Pallas was studied light and electron microscopically. The recessus hypophysei lined with ependymal cells of two main types, “narrow” and “wide”, are in the center of the neurohypophysial “roots”. Processes from both cell types run radially to the basement membrane of the connective tissue layers abutting on the hypophysial intermediate lobe. Protrusions penetrating deep into the recessus hypophyseus are found in the apical parts of the “wide” cells. Pituicytes are rare in the neurohypophysis. The ultrastructure of both ependymal cell types and of the pituicytes is described. Nonmyelinated “Gomori-positive” (peptidergic) neurosecretory A1 and A2 type fibres and their terminals containing elementary neurosecretory granules (1400–1800 Å and 1000–1400 Å respectively) are the main structural elements of the neurohypophysis. Some “dark” and single myelinated neurosecretory fibres have been found. The adrenergic fibres (type B) were described earlier (Polenov et al., 1972a). The structural peculiarities of the neurohypophysis are discussed in functional and comparative-morphological terms.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00307364
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  • 85
    Digitale Medien
    Digitale Medien
    Die Anordnung der Ommatidien in der Retina der Biene (Apis mellifica L.) (1973)
    Springer
    Cell & tissue research 139 (1973), S. 567-582 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Compound Eye ; Apis mellifica ; Polarized light ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung 1. Die Ausrichtung der Rhabdome ist in der Bienenretina nicht konstant. 2. Die Anordnung der exzentrischen Zellen in der Bienenretina ist ebenfalls nicht konstant, und es läßt sich keine symmetrische Verteilung dieser Zellen nachweisen. 3. Die Morphologie der Retina wird im Hinblick auf die Orientierung der Honigbiene nach dem Polarisationsmuster des vom blauen Himmel reflektierten Lichtes diskutiert.
    Notizen: Summary 1. The orientation of the rhabdoms shows no regularity within the retina of the honeybee. 2. The arrangement of the eccentric cells is also irregular within the retina of the honeybee. 3. The morphology of the retina is discussed regarding the ability of the honeybees to orient according to the pattern of the polarization of light reflected from the blue sky.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02028393
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  • 86
    Digitale Medien
    Digitale Medien
    Scanning and transmission electron microscope studies on the sensory sucker papillae of the fish parasite Entobdella soleae (monogenea) (1973)
    Springer
    Cell & tissue research 137 (1973), S. 471-480 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Touch receptors ; Sense organs ; Monogenean ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The ventral surface of the posterior sucker of Entobdella soleae, a monogenean skin parasite of the sole Solea solea, is covered with more than 800 papillae ranging in size from 2.5–19 μm in diameter. The papillae are penetrated by nerves which double over themselves to form a stack-like array of lamellae running parallel to the surface of the haptor. No cilia or associated structures are present within these presumed sense organs and the papillae have no opening to the exterior. The much larger sucker papillae of a related species, E. hippoglossi, have been shown to have a similar ultrastructure. The possibility that the papillae may be contact receptors or strain receptors, providing proprioceptive information assisting the coordination of the attachment organ, is discussed and the papillae are compared with vertebrate touch receptors.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00307224
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  • 87
    Digitale Medien
    Digitale Medien
    Ultrastructural observations on the germ line of Xenopus laevis (1973)
    Springer
    Cell & tissue research 138 (1973), S. 41-62 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Germ cells ; Xenopus ; Spermatogenesis ; Chromatoid body ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The development of the male germ line in Xenopus laevis has been examined by electron microscopy. Findings have been compared to the parallel process in the female. Three structures unique to the germ line were found in both male and female cells: a fibrillar nuclear region free of DNA; largely proteinaceous masses of nuage material; and a chromatoid body. “Germ plasm” bodies of the egg and early embryo appear to represent a form of nuage material. The finding of a structure which can be identified as a chromatoid body in the female germ line is unique, as is its presence in sexually undifferentiated primordial germ cells. The chromatoid body in Xenopus, unlike that in mammals, does not persist in the spermatozoon. Instead, it dissociates into a series of coated vesicles during spermatogenesis. The chromosomal ultrastructure of meiotic prophase stages in Xenopus is similar in both sexes until diplotene, when male bivalents condense and enter meiotic metaphase instead of entering the extended lampbrush stage characteristic of the female. The multiple nucleoli present in gonia are lost at the onset of meiotic prophase, but no obvious mechanism for this process was observed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00307077
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  • 88
    Digitale Medien
    Digitale Medien
    Ultrastructure of the gonadal wall of the sea cucumber, Leptosynapta clarki (echinodermata: holothuroidea) (1973)
    Springer
    Cell & tissue research 141 (1973), S. 319-330 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Gonadal wall ; Holothuroidea (Leptosynapta clarki) ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The holothurian testes (as well as ovary) consists of three layers arranged concentrically around a central lumen which contains developing germ cells. The outer coelomic layer measuring 6 μ in thickness contains ciliated squamous epithelial cells, smooth muscle processes, nerve tracts, and occasional pigment cells. Interior to the outer layer is a haemal sinus measuring about 3 μ and consisting of haemal fluid composed of collagenous fibers and electron dense particles. Coelomocytes are embedded in this extracellular fluid matrix. The inner germinal layer, measuring 9 μ at the thickest regions consists of germinal cells, squamous epithelial cells, and coelomocytes. Occasional coelomocytes within the haemal sinus and germinal layer of the testicular wall contain spermatids enclosed within cytoplasmic vacuoles, suggesting phagocytosis as one of their cellular functions.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00307409
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  • 89
    Digitale Medien
    Digitale Medien
    The granule-containing cell somata in the superior cervical ganglion of the rat, as studied by a serial sampling method for electron microscopy (1973)
    Springer
    Cell & tissue research 141 (1973), S. 331-345 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Sympathetic ganglion ; Granule-containing cells ; Synapses ; Three-dimensional analysis ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The surface of 4 granule-containing cells, in a cluster within the rat superior cervical ganglion, was studied by a serial sampling technique for electron microscopy. The result shows that all the 4 cells receive one, or three afferent synaptic boutons from the preganglionic fibers impinging upon their somata, and a somatic efferent synapse exists at two locations on each soma of the 2 of these cells. The postsynaptic element of the efferent synapse is observed to be represented by non-vesiculated and vesiculated segments of dendrites, soma and a possible axon collateral of the adrenergic principal neuron of the ganglion. There is a remarkably constant development of the attachment plaque between the granule-containing cells themselves, representing 1.7–2.3% of surface area for each cell. The surface area exposed to the extracellular space (covered only by a basal lamina) varies from 0.1 to 2.3% of the total perikaryal surface of the 4 cells. A tendency is noted that those cells without efferent synapses possess a more extensive area exposed to extracellular space than those forming somatic efferent synapse to the postganglionic elements.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00307410
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  • 90
    Digitale Medien
    Digitale Medien
    Fine structure of the developing spore of Nosema apis zander (1973)
    Springer
    Cell & tissue research 141 (1973), S. 469-478 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Microsporida ; Nosema apis ; Developing spore ; Freeze-etching ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The mature spore possesses a thick spore coat and a particle-bearing spore membrane. The highly laminated polaroplast membranes are located at the anterior pole of the spore. Close to its base, the polar filament is surrounded by the polaroplast membrane. The polar filament runs spirally towards the posterior pole of the spore. A large portion of the polar filament is arranged in two layers. A similar arrangement was also observed in immature spores and in the sporoblast stage, although it was not so orderly arranged in the latter. The developing polaroplast membrane was observed in the immature spore, but not in the sporoblast. The sporoblast wall is much thinner than the spore coat, but has the same texture. Endoplasmic reticulum is the most prominent cytoplasmic organelle in the developing stages of Nosema apis. Porous nuclear envelopes are also observed in developing stages. The role of the endoplasmic reticulum in the formation of the polar filament, polaroplast and spore coat, and the function of the spore membrane, are discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00307118
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  • 91
    Digitale Medien
    Digitale Medien
    Fine structure of eyespots in tornarian larvae (Phylum: Hemichordata) (1973)
    Springer
    Cell & tissue research 142 (1973), S. 89-102 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Photoreceptors ; Larva ; Hemichordate ; Ultrastructure ; Evolution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The eyespots of tornariae of enteropneusts (Ptychodera flava from Hawaiian waters and an unknown species from southern California) were studied by electron microscopy. An ocellus is composed of two types of cells: sensory and supportive. The former is characterized by a bulbous cilium (with 9+2 axoneme) at its distal end, one or sometimes two arrays of microvilli from its sides below the cilium, and a basal axon. The latter features large, clear vesicles which presumably contained the reddish-orange pigment seen in the ocellus of a living larva. Five-day old tornariae of P. flava are positively phototactic. Both cilium and microvilli may function as photoreceptors. The tornarian ocellus studied is compared with eyespots of other invertebrates, and the evolutionary significance of its putative photoreceptors is discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00306706
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  • 92
    Digitale Medien
    Digitale Medien
    Ultrastructural features of rat pituicytes in organotypic culture (1973)
    Springer
    Cell & tissue research 143 (1973), S. 107-116 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Neurohypophysis ; Rat ; Pituicytes ; Organotypic culture ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Neural lobes of adult rats have been explanted and organ-cultured for 5–10 days. While perivascular cells and neurosecretory fibers undergo a progressive degeneration, scattered pituicyte-like cells are observed mostly associated with each other in number of two or three cells for group. Cultured pituicytes are quite similar to in vivo pituicytes except for some particular features as the shape of the nucleus and the number of dense bodies. Furthermore they share with the in vivo pituicytes the phagocytic capacity which appears even increased as far as neurosecretory fibers are concerned. Finally, degenerating pituicytes and free lipid droplets are observed in the intercellular spaces: the significance of these facts is discussed and tentatively interpreted. The organotypic culture of the neural lobe seems to represent an experimental model useful to obtain a relatively pure population of pituicytes.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00307454
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  • 93
    Digitale Medien
    Digitale Medien
    Le système nerveux des cténaires (1973)
    Springer
    Cell & tissue research 143 (1973), S. 117-133 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Nervous system ; Ctenophores ; Intra-mesogleal nervous system ; Synapses ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Ultrastructural evidence is given of the occurrence of nervous elements in the mesoglea of Ctenophores based on the presence of the typical synapses of this phylum. In Beroids, nervous fibers from the ectodermal nerve-net cross the epithelial basal membrane and run through the mesoglea; they are devoid of any ensheathing cell. These neurites build highly differentiated synapses upon the muscles and upon peculiar cells, tentatively named mesenchymal cells. In Cydippids, nerve fibers and nerve cell-bodies have been observed in the mesoglea of the tentacles. The mesogleal core of each tentacle contains mesenchymal cells and a thick strand of neurons and neurites, forming a kind of elongated ganglion. Neurites of either the axial neurones or the epithelial nerve-net neurones form numerous radial nerve strands across the tentacular muscles. Interneural, neuro-muscular and neuro-mesenchymal junctions are very frequent in the tentacle. As far as the organization of the mesoglea is concerned, the Ctenophora thus appear closer to Turbellaria than to Cnidaria.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00307455
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  • 94
    Digitale Medien
    Digitale Medien
    Ultrastructural studies of oogenesis in some european amphibians (1973)
    Springer
    Cell & tissue research 143 (1973), S. 387-407 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Oogenesis ; Urodela ; Yolk-formation ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Oogenesis was studied in adult Triturus vulgaris (Urodela) with the electron microscope. The oocytes investigated ranged between 50 μm and 1600 μm in diameter. Two types of yolk platelet formation were found. Since both types involve the incorporation of high numbers of pinocytotic vesicles they are believed to be of an extraoocytic origin. On the basis of the order of their appearance they were named primary and secondary yolk. Five different types of vesicles were found, which participate in a variety of activities, such as yolk formation and the formation of the Golgi apparatus. They originate from four different sources, namely the nuclear membrane, the cytoplasm in connection with ribosome-like particles, the Golgi apparatus and the plasma membrane through pinocytosis. The results obtained were discussed especially with respect to differences found between the anura and the urodela, such as the presence or absence of cortical granules or equivalent structures.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00307423
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  • 95
    Digitale Medien
    Digitale Medien
    Ultrastructure of the rat posterior pituitary gland and evidence of hormone release by exocytosis as revealed by freeze-fracturing (1973)
    Springer
    Cell & tissue research 143 (1973), S. 465-484 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Neurohypophysis ; Membranes ; Exocytosis ; Ultrastructure ; Freeze-fracturing
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Posterior pituitary glands from normal rats, and rats which had been deprived of water for varying periods, were examined by the freeze-fracture method. This technique reveals large areas of the nerve cell membrane. Images consistent with exocytosis as the mechanism of release of the neurohypophysial hormones were observed. These modifications were most numerous after the rat had been starved of water for 2 days. In normal rats, the large number of neurosecretory granules within the nerve fibres caused a bulging of the nerve cell membrane. The “bulges” disappeared 2 days after removal of drinking water. Regions of the membrane displaying “bulges” were characterised by the absence of the typical membrane-associated particles. It is postulated that the close proximity of the neurosecretory granules to the nerve cell membrane may result in rapid fusion of the neurosecretory granules on stimulation of the gland. The change in properties of the nerve cell membrane overlying the neurosecretory granules, as suggested by the loss of membrane-associated particles, may represent a change in the structure of the membrane to a form which is more favourable for fusion.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00306766
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  • 96
    Digitale Medien
    Digitale Medien
    Fine structure of the sensory pore present in the eyestalk of crustacea natantia (1973)
    Springer
    Cell & tissue research 145 (1973), S. 213-227 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Sensory pore ; Crustacea ; Natantia ; Chemoreceptor ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Beschreibung / Inhaltsverzeichnis: Résumé L'observation ultrastructurale du pore sensoriel de plusieurs espèces de Natantia révèle un complexe double. Un premier organe, le pore sensoriel principal, comprend une assise de cellules de soutien encadrant les parties distales de corps de cellules sensorielles. Ces cellules sensorielles portent des segments externes ciliaires qui se divisent dans une cavité sous-cuticulaire aplatie. En regard, la cuticule est amincie et comporte des micropores en forme de cratère et disposés par paires. A côté du pore sensoriel principal, un deuxième organe, le pore sensoriel latéral, est de taille plus réduite et est plus difficile à observer. Sous une invagination digitée de l'épicuticule, existe une cavité de forme complexe où s'épanouissent les segments externes ciliaires d'un faisceau de cellules sensorielles. Le pore sensoriel principal et le pore sensoriel latéral ont une ultrastructure de chémorécepteur.
    Notizen: Summary Ultrastructural observation of the sensory pore of several species of Natantia reveals a twofold organ. A main sensory pore (M.S.P.) comprises a layer of supporting cells which encapsulate the terminal region of sensory cell bodies. These sensory cells include two ciliary processes dividing into a flat sub-cuticular cavity. The cuticle opposite is thin and perforated with crater-like paired micropores. Next to the main sensory pore, a second organ, the lateral sensory pore (L.S.P.), is smaller and more difficult to observe. A complex-shaped cavity underlies a contorted epicuticular invagination. Ciliary outer segments, belonging to a bundle of sensory cells, branch out in this cavity. M.S.P. and L.S.P. appear to be chemoreceptors.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00307389
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  • 97
    Digitale Medien
    Digitale Medien
    Development of muscle spindles deprived of fusimotor innervation (1973)
    Springer
    Cell & tissue research 144 (1973), S. 435-452 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Muscle spindles ; Intrafusal fibre types ; Development ; Deefferentation ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Muscle spindles of limb muscles were deefferented in neonatal rats by sectioning ventral roots or by removal of the lumbosacral spinal cord. Ten to 56 days after the operation, muscle spindles were examined in the medial gastrocnemius, extensor digitorum longus and soleus muscles. The differentiation of muscle spindles was not affected by deefferentation. The number of spindles in the investigated muscles was not reduced. Intrafusal fibres increased in number from two at birth to four per spindle on the average, as in normal muscles. The characteristic ultrastructural distinctions of nuclear bag and nuclear chain fibres developed as under normal conditions. However, intrafusal fibres atrophied slowly after fusimotor denervation, their polar zones becoming reduced in diameter by about 25% in comparison with control fibre diameters. Spindle capsules, on the other hand, increased in size and attained diameters comparable with normal spindles, appearing even somewhat distended. As intrafusal fibres degenerate after complete denervation at birth (Zelená, 1957), but differentiate in the absence of fusimotor innervation, it can be concluded that sensory nerve terminals induce and support their development. It is assumed that the morphogenetic influence of sensory terminals is mediated by release and uptake of a trophic substance at the synaptic junction. The occurrence of light and dense core vesicles in the sensory terminals and of coated invaginations and vesicles at both the axonal and plasma membrane speak in favour of such a possibility.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00307586
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  • 98
    Digitale Medien
    Digitale Medien
    Ultrastructure des cellules de Leydig et des cellules de Sertoli au cours du cycle testiculaire du Canard Pékin (1973)
    Springer
    Cell & tissue research 144 (1973), S. 369-394 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Leydig cells ; Pekin Duck ; Testosterone ; Seasonal cycle ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Beschreibung / Inhaltsverzeichnis: Résumé L'ultrastructure des cellules de Leydig et des cellules de Sertoli du testicule du Canard Pékin a été étudiée au cours de la phase printanière du cycle sexuel, soit de janvier à juillet. Parallèlement on a effectué chez les mêemes animaux la recherche histochimique de la Δ5-3 β-hydroxystéroïdedeshydrogénase (Δ5-3 β-HSDH) ainsi que le dosage, par chromatographie en phase gazeuse des stéroïdes androgènes dans le plasma veineux périphérique et dans le testicule. Les cellules de Leydig du Canard possèdent les organites cytoplasmiques spécifiques des cellules stéroïdogènes (reticulum lisse, mitochondries à crêtes tubulaires) ainsi que d'autres structures souvent rencontrées dans ce type cellulaire (microfilaments, vacuoles, granules denses). Les cellules de Sertoli contiennent un reticulum agranulaire moins développé que celui des cellules de Leydig et, très rarement, des mitochondries à crêtes tubulaires. Ces divers organites cytoplasmiques subissent un cycle saisonnier. La différenciation du reticulum lisse et des crêtes mitochondriales tubulaires commence en janvier et atteint son optimum en mars. Leur régression s'amorce en avril; d'abord accompagnée de structures dégénératives transitoires; elle conduit à la dispartion totale de ces organites en mait. Aucun indice de nécrose n'est observé dans ces cellules. Histochimiquement, une activité Δ5-3 β-HSDH est présente dans les cellules de Leydig et, à un degré moindre, dans les tubes séminifères. Son intensité varie au cours du cycle. La confrontation de l'étude morphologique avec les résultats des dosages hormonaux montre qu'il existe une bonne corrélation entre le développement puis la régression du reticulum lisse et des crêtes tubulaires des mitochondries ainsi que des critères histochimiques de la Δ5-3 β-HSDH d'une part et l'évolution de la testostérone plasmatique et testiculaire d'autre part. De plus on observe une augmentation du rapport testostérone/Δ4-androstènedione testiculaire parallèlement au développement des organites cytoplasmiques. Ces organites semblent donc bien impliqués dans la synthèse et la sécrétion de la testostérone chez le Canard.
    Notizen: Summary Leydig and Sertoli cells of the testis of the Pekin duck were studied ultrastructurally during the spring phase of the sexual cycle, from January to July. Simultaneously, in the same animals, Δ5-3 β-hydroxysteroiddehydrogenase (Δ5-3 β-HSDH) activity was ascertained histochemically and androgenic steroids of the plasma and testes were assayed by gas-liquid chromatography. The Leydig cells of the duck possess cytoplasmic organelles specific to steroidogenic cells (smooth reticulum, tubular mitochondria) as well as other structures often found in this cell type (microfilaments, vacuoles, denses bodies). The Sertoli cells contain an agranular reticulum that is less developed than that of the Leydig cells, and rarely show mitochondria with tubular cristae. These various cytoplasmic organelles undergo a seasonal cycle. The differentiation of the smooth reticulum and the mitochondrial tubular cristae begins in January and reaches a maximum in March. They begin to regress in April, at first with transitory degenerative structures, and then by total disappearance of these organelles by May. No indication of necrosis is observed in the cells. Histochemically Δ5-3 β-HSDH activity is present in the Leydig cells, and to a slightly lesser degree in the seminiferous tubules. The intensity varies during the cycle. The comparison of the results of the morphological study with the hormone assays shows that a good correlation exists with the development and regression of the smooth endoplasmic reticulum and tubular cristae in the mitochondria, as well as the histochemical criteria of the Δ5-3 β-HSDH on one hand, and the levels of plasma and testicular testosterone on the other hand. In addition there is an increase in the ratio of testicular testosterone to Δ4-androstenedione which parallels the development of the cytoplasmic organelles. These organelles thus seem to be implicated in the synthesis and secretion of testosterone in the duck.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00307583
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  • 99
    Digitale Medien
    Digitale Medien
    The ultrastructure of the duct system in the rat extraorbital lacrimal gland (1973)
    Springer
    Cell & tissue research 144 (1973), S. 453-466 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Lacrimal gland ; Rat ; Duct system ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The duct system of the rat exorbital lacrimal gland consists of intercalated ducts, interlobular ducts and excretory ducts. The morphological changes from one type of duct to the next are gradual. At the light microscopical level this consists of a change from a bilaminar epithelium in the intercalated ducts to an epithelium, consisting of approximately three layers — which may be pseudostratified — in the excretory ducts. The basal layer of the intercalated ducts consists of myoepithelial cells, whereas the inner epithelial cells may have both a secretory and an electrolyte transporting function. The interlobular duct epithelium contains many cells with deep infoldings of the basolateral plasma membranes and associated mitochondria, suggesting a similar function to the striated duct epithelium in salivary glands. Numerous basal cells in this epithelium have tentatively been interpreted as unusual myoepithelial cells. Nerve terminals have been observed in the ductal epithelium.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00307373
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  • 100
    Digitale Medien
    Digitale Medien
    The fine structure of the corpus luteum in Hyrax (1973)
    Springer
    Cell & tissue research 144 (1973), S. 475-487 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Luteal cells ; Luteinization ; Endoplasmic reticulum ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Hyrax possess luteal cells with many ultrastructural features similar to those described in other mammalian species. The process of luteinization is gradual. Cells with increasing amounts of smooth endoplasmic reticulum become predominant in the developing gland. The luteal cells of Procavia and Heterohyrax show many ultrastructural similarities. In both species the corpus luteum persists throughout pregnancy.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00307375
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