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  • Digitale Medien  (363)
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  • Digitale Medien  (363)
  • Zeitschrift/Serie
  • Online-Ressource
Erscheinungszeitraum
  • 2010-2014
  • 1990-1994  (59)
  • 1985-1989  (50)
  • 1975-1979  (254)
  • 1955-1959
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  • 1
    Digitale Medien
    Digitale Medien
    Histomorphological aspects of vascular anastomosis established by laser (1991)
    Springer
    Lasers in medical science 6 (1991), S. 363-366 
    Details
    ISSN: 1435-604X
    Schlagwort(e): Laser vascular welding ; Tissue fusion ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin , Physik , Technik allgemein
    Notizen: Abstract The central problem in microsurgery is the reconstruction of small vessels. The long operating time, foreign body granuloma formation around the suture material as well as aneurysmal alterations of the vessel wall after conventional suture technique make the search for alternatives indispensable. Some of these disadvantages can be avoided as demonstrated by our animal experiments and histological examinations in laser-assisted anastomosing. The aim of this study is to show these aspects in connection with laser application and compare them with conventional suture techniques.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02030894
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  • 2
    Digitale Medien
    Digitale Medien
    Organ-specific crystalline structures of ferritin cores inβ-thalassemia/hemoglobin E (1991)
    Springer
    BioMetals 4 (1991), S. 162-165 
    Details
    ISSN: 1572-8773
    Schlagwort(e): Ferritin ; Thalassemia ; Ferrihydrite ; Crystallinity ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Summary The cores of ferritins isolated from different organs of human subjects withβ-thalassemia/hemoglobin E (β-thal/HbE) disease have different size distributions and crystallinities depending on the source organ. These patients have not been treated by hypertransfusion regimen or iron chelation therapy.β-Thal/HbE spleens and livers yield ferritin cores which are less crystalline than those isolated from normal spleens and livers, reflecting the more rapid deposition of iron in the diseased state. Ferritins isolated from the hearts and pancreases ofβ-thal/HbE subjects were found to have larger, more crystalline cores than those from theβ-thal/HbE livers and spleens, possibly as a consequence of the role of the heart and pancreas as long-term iron deposition sites in this iron overload pathology.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01141308
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  • 3
    Digitale Medien
    Digitale Medien
    Claws of cilia: Further observation of ciliated epithelium in neurenteric cyst (1991)
    Springer
    Virchows Archiv 418 (1991), S. 263-265 
    Details
    ISSN: 1432-2307
    Schlagwort(e): Neurenteric cyst ; Enterogenous cyst ; Cilia ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Claw-like projections and related structures on cilium tips in neurenteric cyst epithelium are described. The ciliary claws are about 20 nm in length and just beneath them four parallel electron-dense areas or lines are discernible. Similar structures were also observed in another case of neurenteric cyst. These structures are very similar to those reported previously, and it is suggested that they are commonly present in various ciliated epithelia in Man.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01606065
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  • 4
    Digitale Medien
    Digitale Medien
    Alveolar soft-part sarcoma of the uterine corpus: Histological, immunocytochemical and ultrastructural study of a case (1991)
    Springer
    Virchows Archiv 418 (1991), S. 467-471 
    Details
    ISSN: 1432-2307
    Schlagwort(e): Alveolar soft-part sarcoma ; Uterus ; Myometrium ; Immunocytochemistry ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary A case of alveolar soft-part sarcoma located in the uterine corpus is reported. It was an incidental finding in the hysterectomy specimen of a 40-year-old woman. Light and electron microscopic examination revealed periodic-acid-Schiff-positive, diastase-resistant, membrane-bound cytoplasmic granules and crystalloids. Tumour cells expressed immunoreactivity with vimentin, desmin, cytokeratins, NK1/C3 and HMB-45 antibodies. Four years postoperatively, the patient is still alive without evidence of disease. Differential diagnoses, immunocytochemistry and clinical management of uterine alveolar soft-part sarcoma are discussed and the literature reviewed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01605935
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  • 5
    Digitale Medien
    Digitale Medien
    Glucagonomas of transgenic mice express a wide range of general neuroendocrine markers and bioactive peptides (1991)
    Springer
    Virchows Archiv 419 (1991), S. 115-129 
    Details
    ISSN: 1432-2307
    Schlagwort(e): Transgenic mice ; Glucagonomas ; Immunohistochemistry ; Electron microscopy ; Radioimmunoassay
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Pancreatic tumours of transgenic mice carrying a glucagon-promoted simian virus 40 (SV40) T antigen oncogene have been analysed by histological, histochemical, ultrastructural and radioimmunological means. Seven transgenic mice were examined revealing dysplastic and neoplastic lesions in the endocrine pancreas. Four tumours were identified, one of which metastasized to periadrenal spaces and paravertebral lymph nodes. Benign tumours were composed of argyrophilic, endocrine cells reactive to a range of antibodies against neuroendocrine markers (neuron-specific enolase, protein gene product 9.5, chromogranin A, synaptophysin and protein 7B2) and different fragments of the proglucagon molecule (glucagon, glicentin, glucagon-like polypeptides 1 and 2). A few tumour cells expressed pancreatic polypeptide, somatostatin or insulin. Conventional ultrastructural analysis and immunogold labelling revealed typical glucagon-immunoreactive alpha granules which co-stored glicentin and glucagon-like polypeptides 1 and 2. The malignant primary tumour and its metastases were composed mainly of cells which did not show immunoreactivity for neuroendocrine markers or peptides. Atypical, glucagon-immunogold labelled granules were detected at electron microscopy in differentiated tumour cells and C-type retroviral particles in the largest tumour population of degranulated cells. The transgene-encoded oncoprotein SV40 large T-antigen was detected in the nuclei of well-differentiated tumour cells and in alpha cells of some dysplastic islets. All tumour-bearing mice showed high levels of circulating glucagon-like immunoreactivity. Transgenic mice harbouring the glucagon-promoted SV40 T antigen oncogene may provide a model for human glucagonoma.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01600225
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  • 6
    Digitale Medien
    Digitale Medien
    The pathobiology of salivary gland (1991)
    Springer
    Virchows Archiv 418 (1991), S. 387-400 
    Details
    ISSN: 1432-2307
    Schlagwort(e): Submandibular gland ; Tissue culture ; Electron microscopy ; Proliferating cells
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Fragments of rat submandibular gland (organoids) which maintained the topological organization of the parent tissue were cultured in a three-dimensional collagen gel matrix for up to 30 days. At 48 h, vigorous peripheral outgrowth had occurred around each organoid. This was accompanied by central necrosis and the bridging of adjacent organoids. By day 5, large cyst-like spaces occupied the centre of many organoids. Bromodeoxyuridine labelling indicated that a considerable proportion of the lining cells were proliferating. Organoid growth peaked at between 5 and 10 days. Thereafter, the number of viable colonies and proliferating cells declined. Addition of isoproterenol after 24 h culture resulted in marked morphological alterations, with earlier and more prolific outgrowth and a greater tendency for organoids to flatten and grow out over the surface of the gel with squamous differentiation. Ultrastructurally, nuclear and cytoplasmic features of isoproterenol-treated and untreated cultures were similar. The secretory granules and extensive rough endoplasmic reticulum of terminal tubule cells, evident in organoids immediately after isolation, were infrequent after 24 h and absent by 48 h. Similar alterations occurred in the few acinar cells, so by 5 days the cultures were composed entirely of a uniform population of primitive, dedifferentiated cells. Further uses of this culture systems will include the study of diseases and disorders of the salivary glands as well as normal growth and differentiation pathways.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01605924
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  • 7
    Digitale Medien
    Digitale Medien
    Degeneration of the corticopontine tract in olivopontocerebellar atrophy (1991)
    Springer
    Virchows Archiv 418 (1991), S. 99-103 
    Details
    ISSN: 1432-2307
    Schlagwort(e): Corticopontine tract degeneration ; Olivopontocerebellar atrophy ; Electron microscopy ; Morphometry
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Nine cases of sporadic olivopontocerebellar atrophy [Déjérine-Thomas type, multisystemic atrophy (MSA)] were examined histologically and electron microscopically with special reference to the corticopontine tract. Five of nine cases showed degeneration of the myelinated nerve fibres in this tract. More severe degeneration of the fibres at the level of the pons than the crus cerebri indicates that degeneration of the fibres may start axodistally. Electron microscopy revealed selective involvement of large fibres in olivopontocerebellar atrophy, in contrast to unselective axonal atrophy in dentatorubropallidoluysian atrophy. The problem whether the degeneration of the tract is primary or secondary due to the loss of the pontine neurons remains open. We believe the former to be most likely. Degeneration of the corticopontine fibres should be added to the list of neuropathological findings in sporadic olivopontocerebellar atrophy.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01600284
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  • 8
    Digitale Medien
    Digitale Medien
    Large cell anaplastic lymphoma: Evaluation of immunophenotype on paraffin and frozen sections in comparison with ultrastructural features (1991)
    Springer
    Virchows Archiv 418 (1991), S. 427-433 
    Details
    ISSN: 1432-2307
    Schlagwort(e): Large cell anaplastic lymphoma ; Electron microscopy ; Immunophenotyping
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Eleven cases of large cell anaplastic lymphoma (T typen=5, B typen=4, 0 typen=2) were investigated using electron microscopy and immunophenotyping on formalin-fixed paraffin sections and frozen sections of fresh tissue, to determine whether morphological criteria exist for the discrimination of T, B, and 0 phenotypes. Tumour cell lineage could not be established from ultrastructural features. On paraffin material monoclonal B-cell markers Ki-B5 and L-26 served as reliable tools for recognizing the B phenotype of large cell anaplastic lymphomas (previously determined on fresh material), whereas monoclonal antibodies MT1 (CD43) and UCHL1 (CD45RO) were of limited value in lineage determination.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01605929
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  • 9
    Digitale Medien
    Digitale Medien
    Ultrastructural lipid and glycoconjugate cytochemistry of membranous lipodystrophy (Nasu-Hakola disease) (1991)
    Springer
    Virchows Archiv 419 (1991), S. 137-142 
    Details
    ISSN: 1432-2307
    Schlagwort(e): Membranous lipodystrophy ; Nasu-Hakola disease ; Lipid and glyconconjugate ; Cytochemistry ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary In order to assess the lipid and glycoconjugate characteristics of membranous lipodystrophy, a 29-year-old male with this disease was studied using an ultrastructural cytochemical approach. The specific membranocystic lesions of the disease are composed of cystic spaces and the lining membranes. The membranes were observed to have a two-layered character: microtubular structures in the layer adjacent to the spaces and a central amorphous zone. Lipid staining and the lipase digestion test revealed triglycerides localized not only in the cystic spaces but also in the microtubular structures. Lectin histochemical examintion of carbohydrate components demonstrated thatMaclura pomifera agglutinin bound strongly to the membranes, whileGriffonia simplicifolia I,G. simplicifolia II,Concanavalia ensiformis andTriticum vulgaris agglutinin reacted weakly. Our results indicate the presence of triglycerides and carbohydrates with mainlyα-D-galactose residues in the distinctive membranocystic lesions, in particular in the microtubular structures.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01600227
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  • 10
    Digitale Medien
    Digitale Medien
    Photodynamic therapy of bladder cancer —uptake and phototoxicity of photosan in vitro (1991)
    Springer
    Urological research 19 (1991), S. 353-356 
    Details
    ISSN: 1434-0879
    Schlagwort(e): Bladder cancer ; Electron microscopy ; Photodynamic therapy ; Photosan ; Phototoxicity ; Tumor selectivity ; Video fluorescence microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The uptake of photosan and the intracellular sites of photoradiation-induced damage were investigated in vitro in bladder carcinoma cells and in normal bladder cells. Cells were examined by phase contrast, fluorescence and electron microscopy. The concentration of photosan, measured in μg/106 cells, showed a good correlation to the incubation time. At all incubation times, control cells showed a lower uptake when compared with tumor cells. Following photodynamic therapy (PDT), phase-contrast microscopy revealed marked changes in tumor cells, whereas only minor effects could be detected at the cell membrane of the control cells. Following PDT, most of the investigated cells showed onanges of the mitochondria and cytoplasma. These changes consisted of dissolution of the cristae, predominantly in the central part of the mitochondria. Twenty-four hours after PDT the shape of the mitochondria had changed markedly and the cristae were found to be completely destroyed. Moreover, the cystoplasma showed numerous vacuoles, and the number of mitochondria was decreased compared to non-treated cells.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00310149
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  • 11
    Digitale Medien
    Digitale Medien
    Widely distributed Bunina bodies and spheroids in a case of atypical sporadic amyotrophic lateral sclerosis (1991)
    Springer
    Acta neuropathologica 81 (1991), S. 349-353 
    Details
    ISSN: 1432-0533
    Schlagwort(e): Amyotrophic lateral sclerosis ; Bunina body ; Clarke's nucleus ; Onuf's nucleus ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary We report the autopsy findings of an 81-year-old patient with short-course sporadic amyotrophic lateral sclerosis lasting approximately 5 months. Pathological findings were probably very early. Light microscopy showed abundant eosinophilic Bunina type inclusions widely distributed not only in the motor neurons of the spinal cord and brain stem but also in neurons of the Onuf's and Clarke's nuclei. Fine structural study revealed that the inclusions seen in the Clarke's nuclei were identical to Bunina bodies observed in anterior horn cells. A direct connection between axonal swelling and perikaryon was often seen in the facial and hypoglossal nuclei and in the spinal cord. Ubiquitin-positive Lewy body-like inclusions and central chromatolysis-like changes were also found in the anterior horn cells.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00305880
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  • 12
    Digitale Medien
    Digitale Medien
    Distribution of synapses on an intracellularly labeled small pyramidal neuron in the cat motor cortex (1991)
    Springer
    Anatomy and embryology 184 (1991), S. 313-318 
    Details
    ISSN: 1432-0568
    Schlagwort(e): Pyramidal neurons ; Motor cortex ; Synapses ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The morphological characteristics and distribution of synapses on a small pyramidal neuron in layer III of the cat motor cortex have been studied by combining intracellular HRP staining and electron microscopic examination. The stained neuron showed spiny apical and basal dendritic profiles under the light microscope, and exhibited the morphological features of a pyramidal neuron. Ultrastructural analysis indicated that about 80% of the presynaptic terminals formed asymmetrical synapses with spines of distal apical and basal dendrites. On proximal apical dendrites, 64% of the synapses were found to make contact with spines, and 16.7% of the synapses were of symmetrical type and formed with dendritic shafts. Two types of terminal could be identified on the soma; they were alternately located and established symmetrical and asymmetrical synaptic contacts respectively. Possible functional implications are discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01673266
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  • 13
    Digitale Medien
    Digitale Medien
    The costo-uterine muscle of the rat (1991)
    Springer
    Anatomy and embryology 184 (1991), S. 337-343 
    Details
    ISSN: 1432-0568
    Schlagwort(e): Costo-uterine muscle ; Innervation ; Fluorescence histochemistry ; Electron microscopy ; Morphometry ; Rat (Wistar)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The costo-uterine muscle provides a skeletal attachment to the longitudinal myometrial layer of the uterine horn. In this study we investigated the possibility that the muscle is responsive to sex steroid hormones. In rats of 4 weeks of age, injected with oestradiol for 5 days, the cross-sectional area of nucleated muscle cell profiles was significantly increased. A significant increase in the sectional area of muscle cells was also demonstrated in the costo-uterine muscle of 16-week-old rats, on the 20th day of gestation, compared with nonpregnant rats in dioestrus and of the same age. In oestrogen-treated and in pregnant rats, there was also an increase in muscle cell length. As to the innervation of the costo-uterine muscle, in glyoxylic acid-treated whole-mount and cryostat preparations, we found not only perivascular nerve fibres, but also a few nerve fibres innervating the muscle proper. The pattern of innervation was unchanged after oestrogen treatment and during pregnancy. In the electron microscope, axonal varicosities were observed in the proximity of both vascular and non-vascular muscle cells.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00957895
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  • 14
    Digitale Medien
    Digitale Medien
    Ultrastructural changes in the gracile nucleus of the rat after sciatic nerve transection (1991)
    Springer
    Anatomy and embryology 184 (1991), S. 591-604 
    Details
    ISSN: 1432-0568
    Schlagwort(e): Spinal nerves ; Dorsal column nuclei ; Nerve degeneration ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Ultrastructural changes in the gracile nucleus of the rat have been examined after peripheral nerve injury. The sciatic nerve of adult rats was transected at mid-thigh level, and after survival times ranging from 1 day to 32 weeks sections from the gracile nucleus were prepared for electron microscopic examination. Unoperated animals served as controls. Atypical profiles were regularly observed in the experimental cases at post-operative survival times from 3 days up to 32 weeks. It was sometimes not possible to classify these as pre-terminal axons or terminals, because synaptic contacts could not be identified. The two most common changes throughout the entire post-operative period were greatly expanded myelinated axons, or unmyelinated profiles containing numerous mitochondria, osmiophilic dense bodies and vacuoles. Atypical profiles were occasionally observed in unoperated control animals. The results clearly show that various types of degenerative changes occur in the gracile nucleus after peripheral nerve injury. These changes differ markedly from previously described transganglionic changes in other systems. It cannot be excluded that some of the changes reflect growth-related reactions, although the typical features of axon regeneration could not be found.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00942581
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  • 15
    Digitale Medien
    Digitale Medien
    Elucidation of three-dimensional ultrastructure of Hirano bodies by the quick-freeze, deep-etch and replica method (1991)
    Springer
    Acta neuropathologica 81 (1991), S. 248-254 
    Details
    ISSN: 1432-0533
    Schlagwort(e): Hirano bodies ; Unit lamellae ; Alzheimer's disease ; Rapid-freeze, deep-etch and replica ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary To clarify the yet controversial fine structure of Hirano bodies, we made three-dimensional observations of the tissues from the right hippocampus obtained at autopsy of elderly patients by the quick-freeze, deep-etch and replica method. The basic structure of Hirano bodies was a unit lamella, a closely attached pair of sheets composed of parallel-running smooth filaments, 10 to 12 nm in diameter with 12-nm interspaces. In the unit lamella, filaments from each of the overlapping sheets crossed obliquely at acute or obtuse angles to form lattice-like meshworks. The unit lamellae were arranged in a folded, waved or concentric manner, and connected or supported by cross-linking filaments of the same width. The distance between these unit lamellae was about 50 nm. Occasionally the sheets were separated or fused making layers of one to three sheets. At the periphery of the bodies parallel filaments were dispersed into individual filaments of similar size or directly attached to the cytoplasmic membrane.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00305865
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  • 16
    Digitale Medien
    Digitale Medien
    Light and electron microscopic and immunohistochemical observations of the Onuf's nucleus of amyotrophic lateral sclerosis (1991)
    Springer
    Acta neuropathologica 81 (1991), S. 610-614 
    Details
    ISSN: 1432-0533
    Schlagwort(e): Amyotrophic lateral sclerosis ; Bunina body ; Onuf's nucleus ; Ubiquitin ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary We examined the Onufrowicz nucleus (Onuf's nucleus) of ten sporadic amyotrophic lateral sclerosis (ALS) patients with light and electron microscopic and immunohistochemical methods. Neurons in the Onuf's nucleus of ALS patients were better preserved than those in anterior horn cells. However, some showed morphological changes in the nucleus, namely, central chromatolytic changes, Bunina bodies, ubiquitin-positive filaments and spheroids. The Onuf's neurons of ALS patients showed more argentophilia than those of non-ALS patients. Electron microscopic observations revealed that neurofilaments were relatively more numerous in the Onuf's neurons of ALS patients. Bunina bodies and degenerated neurites were also seen in the Onuf's nucleus. In conclusion, the Onuf's nucleus in sporadic ALS patients showed some morphological changes similar to those noted in anterior horn cells.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00296370
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  • 17
    Digitale Medien
    Digitale Medien
    Ultrastructure of diffuse plaques in senile dementia of the Alzheimer type: comparison with primitive plaques (1991)
    Springer
    Acta neuropathologica 82 (1991), S. 13-20 
    Details
    ISSN: 1432-0533
    Schlagwort(e): Alzheimer-type dementia ; Senile plaques ; Amyloid β/A4 protein ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary We compared the ultrastructure between diffuse and primitive plaques in the brains of senile dementia, using pairs of routine electron microscopic ultrathin sections and adjacent semithin sections, which were immunolabeled for β protein. In the frontal cortex, amyloid fibrils were rarely seen in a minority of diffuse plaques, suggesting an initial stage of the diffuse plaques. A majority of the diffuse plaques had electrondense material and/or amyloid fibrils between cell processes in part of but not the entire β/A4-immunoreactive areas. Small degenerating neurites were often seen with apparent amyloid fibrils in the diffuse plaques, and these were considered to be in an advanced stage. The size and number of degenerating neurites were proportional to the amount of amyloid. Bundles of amyloid fibrils were occasionally surrounded by astroglial processes forming gap junctions. Neurons were found within some diffuse plaques, but capillaries were rarely seen. In contrast, in the temporal cortex, the diffuse plaques were smaller, and even these small ones had apparent amyloid fibrils. The amount of amyloid correlated significantly with plaque size in the temporal cortices, but not in the frontal cortices. Most of the diffuse plaques of the frontal lobe remained as advanced diffuse plaques (apparent amyloid with occasional astroglia and some degenerating neurites) for a long time, and did not transformed into primitive plaques, whereas the temporal diffuse plaques tended to transform into primitive plaques.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00310918
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  • 18
    Digitale Medien
    Digitale Medien
    Microtubule bundles in fish cerebellar Purkinje cells (1991)
    Springer
    Anatomy and embryology 183 (1991), S. 105-110 
    Details
    ISSN: 1432-0568
    Schlagwort(e): Initial axon segment ; Microtubules ; Cross-bridges ; Golgi apparatus ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The initial axon segments and the cell bodies of Purkinje cells were examined in electron microscopic serial sections and toluidine blue semithin sections of goldfish cerebellum. We observed two characteristic cytoplasmic features different from those of other vertebrate neurons. 1. The areas of Nissl substance and Golgi apparatus are sharply divided in the periphery and center of the cytoplasm. 2. Microtubules fasciculated by cross-bridges in the axon hillock and initial axon segment remain bundled in the perikaryon, pass near the eccentric nucleus, and enter into the Golgi area of the central cytoplasm, where they are surrounded by mitochondria. We suggest that the intracellular fasciculated microtubules may establish a prepared pathway for fast anterograde and retrograde transport to and from the Golgi area of the cell body.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00174390
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  • 19
    Digitale Medien
    Digitale Medien
    Elastic-like tissue, a new component of the renal glomerular capillary wall in a cartilaginous fish (1991)
    Springer
    Anatomy and embryology 183 (1991), S. 475-481 
    Details
    ISSN: 1432-0568
    Schlagwort(e): Elastic-like tissue ; Elasmobranch ; Glomerular capillary wall ; Kidney ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Elastic-like tissue composed of tubular microfibrils continuous with, and disappearing into, amorphous material is present in the connective tissue space of the glomerular capillary wall of the river ray (freshwater elasmobranch) kidney. The amorphous material is stained by tannic acid but not by uranyl acetate. Structures with similar morphology and staining characteristics are also found in the subendothelial connective tissue layer of renal arteries in this species. Comparative ultrastructural observations of kidneys from marine rays show elastic-like tissue in the arterial wall but not in the glomerular vessels.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00186436
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  • 20
    Digitale Medien
    Digitale Medien
    Immunohistochemistry of primitive neuroectodermal tumors in infants with special emphasis on cytokeratin expression (1991)
    Springer
    Acta neuropathologica 82 (1991), S. 494-501 
    Details
    ISSN: 1432-0533
    Schlagwort(e): Primitive neuroectodermal tumor ; Cytokeratin immunohistochemistry ; Double labelling ; Electron microscopy ; Immunoblotting
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Eleven primitive neuroectodermal tumor (PNET) biopsies from infants under the age of 3 years were studied for the presence of various differentiation markers for neuroectodermal stem cells. Special emphasis was placed on the expression of cytokeratin proteins. The tumor cells expressed different cytokeratin proteins (CK8, CK13, CK18, CK19, KL1, AE1/AE3, MNF16) in 3 of 11 cases. These cases were furthermore characterized by a strong expression of glial fibrillary acidic protein, S-100 protein and vimentin. Vimentin and cytokeratin proteins were co-expressed; cross-reactivity between these two intermediate filaments could be excluded by immunoblotting. It is noteworthy that the three positive tumors were all from infants in their 1st year. We assume that PNETs in early infancy are characterized by a particularly wide range of differentiation patterns. The presence of cytokeratin proteins in these cases seems to be associated with the expression of vimentin and must be regarded as an indicator of an early developmental stage of the tumor cells.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00293384
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  • 21
    Digitale Medien
    Digitale Medien
    Recessive ichthyosis congenita type II (1991)
    Springer
    Archives of dermatological research 283 (1991), S. 211-218 
    Details
    ISSN: 1432-069X
    Schlagwort(e): Ichthyosis ; Histopathology ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary In the hetereogeneous group of recessive congenital ichthyoses the disorder of desquamation seems to be a basic problem. Desquamation is strongly dependent on the normal lipid metabolism of the keratinocytes. We describe a group of patients who have a typical clinical picture of large scale ichthyosis and cholesterol clefts in the thickened corneal layer, evidencing a disturbance of the lipid metabolism of the skin. The corneocytes also show a thin or absent cornified envelope, which could indicate a disturbance of protein synthesis. These patients have a severe ichthyosis, but good general health and no associated symptoms. This disorder has recently been named ‘ichthyosis congenita type II’ by the Heidelberg group on the basis of electron microscopic findings. According to the present examination this group corresponds clinically to the currently used diagnosis ‘lamellar ichthyosis’.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01106104
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  • 22
    Digitale Medien
    Digitale Medien
    The effect of the proteolytic enzyme savinase on human plantar skin in vitro (1991)
    Springer
    Archives of dermatological research 283 (1991), S. 377-381 
    Details
    ISSN: 1432-069X
    Schlagwort(e): Savinase ; Proteolytic enzyme ; Human plantar skin ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The effect of the proteolytic enzyme savinase on human plantar skin in vitro was examined by light and electron microscopy to elucidate the morphological involvement of activated savinase in human epidermis. Light microscopic examination of incubated skin fragments demonstrated that the histological changes produced by savinase in the epidermis, including the stratum corneum, depended upon pH value, enzyme concentration and incubation time. After incubation in 0.1% savinase in phosphate buffer, pH 8.0, for 2 h at 35
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00371819
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  • 23
    Digitale Medien
    Digitale Medien
    Ultrastructure of giant and small thalamic terminals of cortical origin: a study of the projections from the barrel cortex in mice using Phaseolus vulgaris leuco-agglutinin (PHA-L) (1991)
    Springer
    Experimental brain research 87 (1991), S. 159-172 
    Details
    ISSN: 1432-1106
    Schlagwort(e): Corticothalamic projection ; Somatosensory system ; Barrel ; Phaseolus vulgaris ; leucoagglutinin ; Electron microscopy ; Mouse ; Synaptic glomerulus
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary By means of tracing with the lectin Phaseolusvulgaris leucoagglutinin (PHA-L), we examined in the thalamus of the mouse, the axon terminals of fibers originating in the barrel cortex. Vibratome sections of the brain were subjected to PHA-L immunocytochemistry and processed for light and electron microscopy. We observed small (0.5–0.8 μm in diameter) varicosities of labeled fibers in the nucleus ventrobasalis (VB) and the nucleus posterior (PO) as well as labeled giant terminals (3–5 μm in diameter) in PO. The analysis involved examination of serial sections and computer-aided reconstruction of several terminals. The small varicosities in VB appear to be small axon terminals forming distinct asymmetric synapses with small dendritic profiles. Some labeled terminals are apposed to, but not synaptically related with, the cell bodies of neurons in VB that are retrogradely labeled with PHA-L. The small varicosities seen with the light microscope in PO are terminals forming asymmetric synapses with dendritic shafts. The giant terminals in PO appear as large, vesicle-filled profiles forming part of synaptic glomeruli, i.e. complexes of one corticothalamic terminal engulfing several excrescences of a single dendrite. A giant terminal forms several asymmetric synapses (about 8) with these excrescences, as well as numerous (up to 15) puncta adhaerentia. The glomeruli are enveloped in glial lamellae, and they are often found at the bifurcations of primary dendritic segments. We suggest that the small terminals in VB are in the service of feedback signalling from the barrel cortex to its principal thalamic relay nucleus; the functional importance of this projection may reside in increased spatio-temporal discrimination. We interpret the giant terminals in PO as elements serving feed-forward processing, allowing the barrel cortex to influence, via PO, parts of the motor pathway modulating the animal's ongoing behavior.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00228517
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  • 24
    Digitale Medien
    Digitale Medien
    The fine structure of serotonin and tyrosine hydroxylase immunoreactive terminals in the ventral posterior thalamic nucleus of cat and monkey (1991)
    Springer
    Experimental brain research 85 (1991), S. 507-518 
    Details
    ISSN: 1432-1106
    Schlagwort(e): Serotonin ; Tyrosine hydroxylase ; Electron microscopy ; Thalamus ; Cat ; Monkey
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Immunocytochemical methods have been combined with serial thin section analysis to study the synaptic organization of serotonin (5-HT) and tyrosine hydroxylase (TH) immunoreactive terminals in the ventral posterior nucleus of the cat and monkey thalamus. One hundred 5-HT immunoreactive terminals from the cat and approximately forty 5-HT and TH immunoreactive terminals from the monkey were selected for analysis in serial thin sections. Only 7–10% of the immunoreactive terminals could be revealed to form conventional synaptic contacts. Most of these could be identified as the asymmetrical type. Dendritic shafts belonging to relay neurons were the major targets of these monoamine immunoreactive terminals. The remainder made intimate membrane associations with relay cell dendrites and somata or with presynaptic dendrites of interneurons, but no overt membrane specializations could be detected. The present results suggest that the modulation of thalamocortical relay function by brainstem monoamine pathways in the somatosensory thalamus may occur by release of transmitters at atypical contact sites.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00231734
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  • 25
    Digitale Medien
    Digitale Medien
    Corneal edema induced by bis (tributyltin) oxide (1991)
    Springer
    Archives of toxicology 65 (1991), S. 651-655 
    Details
    ISSN: 1432-0738
    Schlagwort(e): Bis (tributyltin) oxide ; Corneal edema ; Electron microscopy ; X-ray microanalysis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Comeal edema induced by bis (tributyltin) oxide (TBTO) was studied with an electron microscope and the accumulation sites of tin were determined with an X-ray microanalyzer. Male Wistar rats received an intramuscular injection of 0.5 ml/kg TBTO. After time intervals of 2,4, 6, 8, 10, 12 h after injection, corneas were isolated and provided for electron microscopy. Corneas from untreated rats served as controls. Marked swelling of mitochondria in the corneal endothelial cells occurred at 4 h after TBTO injection. The corneal edema appeared in the endothelial layer and the stroma at 6 h after injection. By X-ray microanalysis, Sn peaks were obtained from swollen mitochondria in the endothelial cells. At 12 h after TBTO injection, edematous swelling of the corneal tissue became more advanced. These results indicated that parenterally administered TBTO accumulated in the mitochondria of corneal endothelial cells. The direct toxic effects of TBTO on the mitochondria might cause the interference with active pump function of endothelial cells and induced the corneal edema.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02098031
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  • 26
    Digitale Medien
    Digitale Medien
    In vitro and in vivo uptake of nickel sulfides by rat lymphocytes (1991)
    Springer
    Archives of toxicology 65 (1991), S. 324-329 
    Details
    ISSN: 1432-0738
    Schlagwort(e): αNi3S2 ; βNiS ; Rat lymphocytes ; Electron microscopy ; Energy dispersive spectrometry ; Sulfur phosphorus shift ; Biological transformation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract The uptake, the biological transformation and the interaction with cellular constituents of αNi3S2 and βNiS have been studied in vitro and in vivo on rat lymphocytes. βNiS crystals are phagocytized in vitro and no structural degradation is observed within the first 3 days of exposure. Energy dispersive spectrometry (EDS) reveals a slight dissolution characterized by the loss of sulfur. αNi3S2 is degraded in the extracellular space to minute particles (50–100 nm) covering the cell membrane. Smaller intracellular particles (10–30 nm) are found selectively bound to mitochondria, endoplasmic reticulum, Golgi vesicles, nuclear membranes, and the euchromatinic part of nuclei. EDS analyses reveal that the particles bound to cell membranes and euchromatin no longer contain sulfur but phosphorus and nickel as inorganic compounds. This observation suggests the formation of a Ni/P complex with the phosphate groups either of membranous phospholipids or of nuclear RNA or DNA. A similar uptake and transformation process of αNi3S2 is observed on lymphocytes after in vivo incubation. This leads us to consider lymphocytes as target cells, as compared with other cell types where the αNi3S2 uptake occurs only partially. The present findings show a difference of uptake and biological transformation between αNi3S2 and βNiS. The identical results obtained after in vitro and in vivo bioassays enhance the in vitro experiments, at least for this cell type.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01968967
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  • 27
    Digitale Medien
    Digitale Medien
    Surface reconstruction from stereoscopy and “shape from shading” in SEM images (1991)
    Springer
    Machine vision and applications 4 (1991), S. 271-285 
    Details
    ISSN: 1432-1769
    Schlagwort(e): Electron microscopy ; three-dimensional vision ; surface reconstruction ; stereo ; shape from shading ; dynamic programming
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Informatik
    Notizen: Abstract The computational reconstruction of surface topographies from scanning electron microscope (SEM) images has been extensively investigated in the past, but fundamental image processing problems still exist. Since conventional approaches adapted from general-purpose image processing have not sufficiently met the requirements in terms of resolution and reliability, we have explored combining different methods to obtain better results. This paper presents a least-squares combination of conventional stereoscopy with “shape from shading” and a way of obtaining self-consistent surface profiles from stereoscopy and “stereo-intrinsic shape from shading” using dynamic programming techniques. Results are presented showing how this combined analysis of multi-sensorial data yields improvements of the reconstructed surface topography that cannot be obtained from individual sensor signals alone.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01815304
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  • 28
    Digitale Medien
    Digitale Medien
    Structural aspects of the soluble NAD-dependent hydrogenase isolated from Alcaligenes eutrophus H16 and from Nocardia opaca 1b (1991)
    Springer
    Archives of microbiology 155 (1991), S. 303-308 
    Details
    ISSN: 1432-072X
    Schlagwort(e): Soluble NAD-dependent hydrogenase ; Alcaligenes eutrophus ; Nocardia opaca ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The soluble NAD-dependent hydrogenase (hydrogen-NAD oxidoreductase, EC 1.12.1.2), consisting of four non-identical subunits, was isolated from Alcaligenes eutrophus H16 and from Nocardia opaca 1b and analyzed by a HPLC gel permeation technique and electron microscopy. The tetrameric enzyme particles from both origins, as determined from negatively stained electron microscopic samples, were found to be elongated and very similar in shape and size. The A. eutrophus enzyme was measured in more detail. It exhibited dimensions of 12.7 nm by 5.5 nm (axial ratio 2.3:1). Dissociation into smaller particles and unspecific aggregation combined with partial inactivation were observed in the presence of the inhibitor NADH. Kept in buffer without added nickel, the enzyme was partially dissociated. Reassociation of tetramers without restored enzyme activity was achieved by addition of 0.5 mM NiCl2. A working model for the structural organization of the tetrameric enzyme particle is presented.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00252217
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  • 29
    Digitale Medien
    Digitale Medien
    Serotonergic effects on carbonic anhydrase activity in the choroid plexus (1991)
    Springer
    Child's nervous system 7 (1991), S. 442-447 
    Details
    ISSN: 1433-0350
    Schlagwort(e): Acetazolamide ; Carbonic anhydrase activity ; Choroid plexus ; Electron microscopy ; Serotonin ; Tetrabenazine
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract The carbonic anhydrase (CA) activities in the choroid plexus of dogs were investigated by electron microscopy, and the effects of 5-hydroxytryptophan (5-HTP) on them were examined to elucidate the participation of serotonin in the production of cerebrospinal fluid. The reaction products yielded by the method employed proved to be CA activity by elimination tests using acetazolamide (Diamox). Following administration of 5-HTP, the CA activities fell to 43.3% of the control value, that is, approximately 56% of the CA activities in the choroid plexus were affected by serotonin. When tetrabenazine (TBZ) was administered, the CA activities in the choroid plexus decreased to 22.4% of the control value. These results suggest that the CA activity in the choroid plexus is remarkably suppressed when nervous control of the choroid plexus is disturbed by the administration of a monoamine denervator such as TBZ. The present data indicate that the serotonergic inhibitory effect on the CA activity in the choroid plexus may be less predominant than that of TBZ and acetazolamide.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00263186
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  • 30
    Digitale Medien
    Digitale Medien
    A cytochemical and immunocytochemical study of DNA distribution in spermatid nuclei of mouse, rabbit, and bull (1991)
    Springer
    Cell & tissue research 265 (1991), S. 517-525 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Spermiogenesis ; Spermatids ; DNA ; Immunocytochemistry ; Electron microscopy ; Bovine ; Mouse ; Rabbit
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary DNA distribution in mouse, rabbit and bull spermatids was analyzed by electron microscopy, after using a Feulgen-like HCl-osmium ammine procedure, and after immunocytochemistry with anti-DNA antibodies. In addition, nucleic acids were visualized with the intercalating dye ethidium bromide and phosphotungstic acid. The parts of DNA displaying a beta helix configuration (possibly A-T rich parts) were identified by epifluorescence microscopy after staining with Hoechst 33258. In all 3 species, young spermatid nuclei were seen to have large areas poor in DNA, as well as DNA-rich areas, which were mostly concentrated into a peripheral layer close to the acrosome and into one or several masses, displaying species-specific locations. These DNA-rich areas were stained with Hoechst 33258. Elongating spermatid nuclei contained homogeneously distributed DNA, and this was evident following both immunocytochemistry and nucleic acid histochemistry in all 3 species. However, the distribution appeared more heterogeneous after the Feulgen-like procedure, and was accompanied by a disappearance of Hoechst-fluorescence. In fully elongated spermatids, all nuclear areas stained with Hoechst 33258, while the 3 other techniques labeled either all or species-specific parts of the condensed chromatin. The reasons for these variable reactions are discussed in terms of technique specificities, DNA configuration and nucleoprotein moiety replacements.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00340875
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  • 31
    Digitale Medien
    Digitale Medien
    Transient expression of a calcium-binding protein (spot 35-calbindin) and its mRNA in the immature pituicytes of embryonic rats (1991)
    Springer
    Cell & tissue research 266 (1991), S. 325-330 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Calbindin ; Neurohypophysis ; Development, ontogenetic ; Immunohistochemistry ; In-situ hybridization ; Electron microscopy ; Rat (Wistar)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Spot 35 protein is a Ca-binding protein originating from the rat cerebellum; it is now referred to spot 35-calbindin. This protein is expressed in immature pituicytes of the neurohypophyseal anlage in the E11–E18 rat embryo. The gene expression of spot 35-calbindin was detected by in-situ hybridization analysis only at stage E11–E12. Profiles of spot 35-positive nerve fibers of a neurosecretory nature were found in anlage at stage E16. At this stage, some immature pituicytes are partially immunopositive for spot 35-calbindin only in their peripheral cytoplasm; others are immunonegative. At birth and thereafter through adulthood, abundant nerve fibers are the sole structures immunoreactive for spot 35-calbindin; all the pituicytes are immunonegative, resulting in a light-microscopic appearance of numerous immunonegative round profiles, corresponding to pituicytes, and capillaries embedded in the granularly immunostained neurohypophysis. The present findings suggest that, during specific embryonic stages, immature pituicytes exert some as yet unidentified roles related to Ca-mediated functions involving the expression of spot 35-calbindin.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00318188
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  • 32
    Digitale Medien
    Digitale Medien
    Development of the basal lamina in xenografted human carcinomas: an ultrastructural and immunohistochemical study (1991)
    Springer
    Cell & tissue research 266 (1991), S. 563-578 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Xenografted human carcinomas ; Basal lamina ; Development, following heterotransplantation ; Electron microscopy ; Immunofluorescence microscopy ; Man ; Mouse (NMRI, nu/nu)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The development of the basal lamina (BL), the key structure of the basement membrane (BM), was investigated in three xenografted human carcinomas of the sigmoid colon (CA 1), the lung (L 261), and the hypopharynx (H-Stg 1) following heterotransplantation to athymic mice. The study involved the use of electron microscopy and indirect immunofluorescence techniques employing highly specific antibodies against the intrinsic BL components, heparan sulfate proteoglycan, laminin and type-IV collagen. Following transplantation, the extracellular matrix material of the transplanted tumors decomposed and was phagocytozed by invading macrophages within 1 to 2 days. During this stage, no specific binding of the applied antibodies to BL components could be detected within the xenografts. Following the ingrowth of host-derived connective tissue between days 2 to 6, small fluorescence-positive granules appeared within the cytoplasm and around those tumor cells that were located close to the invaded strands of connective tissue. Ultrastructurally, typical secretory granules were detectable in the cytoplasm of many xenografted carcinoma cells. Thereafter, a tannic acid-positive, patchy material appeared in the extracellular space of CA 1 and L 261 and aggregated to form small fragments of a discontinuous BL. In the H-Stg 1 xenografts, this material assembled to form continuous mono-, bi- and multilayered structures. Large amounts of excess BL material remained accumulated in the L 261 and H-Stg 1 xenografts until the end of the observation period (day 24). These findings reveal that discontinuities of the BL occur independent of the active invasion processes of tumor cells, since xenografted human carcinomas neither grow invasively nor metastasize in nude mice. Moreover, they confirm that these discontinuities are not caused by a quantitatively insufficient production of BL material, but rather arise from qualitative imbalances of the composition of the synthesized BL material.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00318598
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  • 33
    Digitale Medien
    Digitale Medien
    Initiation of acellular extrinsic fiber cementum on human teeth (1991)
    Springer
    Cell & tissue research 263 (1991), S. 311-324 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Dental root surface ; Periodontal fiber fringe ; Dentino-cemental junction ; Electron microscopy ; Human
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The development of acellular extrinsic fiber cementum (AEFC) has never before been studied in human teeth. We have therefore examined the initiation of AEFC in the form of a collagenous fiber fringe and its attachment to the underlying dentinal matrix, in precisely selected, erupting human premolars with roots developed to 50%–60% of their final length. Freshly extracted teeth were prefixed in Karnovsky's fixative, decalcified in EDTA and subdivided into about 10 blocks each, cut from the mesial and distal root surfaces, vertical to and along the root axis. The blocks were postfixed in osmium tetroxide, embedded in Epon and cut for light- and electron-microscopic investigation. Starting at the advancing edge of the root, within a region extending about 1 mm coronal to this edge, fibroblast-like cells were seen closely covering the external root surface. Along the first 100 μm from the root edge, these cells extended cytoplasmic processes and contacted the dentinal collagen fibrils. Between these cells and the dentinal matrix, new collagen fibrils and very short collagen fibers gradually developed. Within the second 100 μm from the root edge, this resulted in the formation of a cell-fiber fringe network. Newly formed fibers of the fringe were directly attached to the non-mineralized matrix containing dentinal collagen fibrils and could be distinguished from the latter by differences in fibril orientation. During the process of dentin mineralization, the transitional zone between the fiber-fringe base and the dentinal matrix, i.e., the future dentino-cemental junction, also mineralized. It is suggested that this fiber fringe is the base of AEFC, which later increases in thickness by fiber extension and subsequent mineralization.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00318773
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  • 34
    Digitale Medien
    Digitale Medien
    Establishment of acellular extrinsic fiber cementum on human teeth (1991)
    Springer
    Cell & tissue research 263 (1991), S. 325-336 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Cementum ; Fiber fringe ; Periodontal ligament fibers ; Dentino-cemental junction ; Electron microscopy ; Human
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The present study describes for the first time the development of early acellular extrinsic fiber cementum (AEFC) until its establishment on human teeth. Precisely selected premolars with roots developed to 50%–100% of their final length were prefixed in Karnovsky's fixative and most of them were decalcified in EDTA. Their roots were subdivided into about 10 blocks each, cut from the mesial and distal root surfaces. Following osmication, these blocks were embedded in Epon and sectioned for light-and transmission electron microscopy. Some blocks were cut non-demineralized. From semithin stained sections, the density of the collagenous fiber fringe protruding from the root surface was measured by using the Videoplan-system. After initiation of this fiber fringe and its attachment to the dentinal root surface followed by mineralization, the fringe gradually increased in length and subsequently became mineralized. Fringe elongation and the advancement of the mineralization front appeared to progress proportionally. Thus, in all stages of AEFC development, a short fiber fringe covered the mineralized AEFC. Its density remained constant, irrespective of AEFC thickness. The latter gradually increased and reached an early maximum of 15–20 μm in the cervical region. At this stage, the AEFC fringe appeared to fuse with the future dentogingival or other collagen fibers of the tooth supporting apparatus. Mineralization of the fringe commenced with isolated, spherical or globular centers, which later fused with the mineralization front and became incorporated in AEFC.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00318774
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  • 35
    Digitale Medien
    Digitale Medien
    Ultrastructural study of a cytoplasmic bridge connecting a pair of erythroblasts in mice (1991)
    Springer
    Cell & tissue research 264 (1991), S. 215-219 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Erythroblast ; Cytokinesis ; Cytoplasmic bridge ; Fetal liver ; Erythropoiesis ; Electron microscopy ; dd Mice
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary A unique cytoplasmic connection between erythroblasts was studied by electron microscopy in mouse hemopoietic tissues (fetal liver, fetal and neonatal spleen and adult bone marrow). Many pairs of interphase erythroblasts were connected by a “cytoplasmic bridge” that was very thin and sometimes long in comparison with telophase bridges. The stage of maturation of the cells in a pair was similar. Small numbers of microtubules ran along the cytoplasmic bridge; a mid-body was not seen. The plasma membrane at approximately the middle of the bridge bulged to form a ring-shaped ridge filled with dense amorphous substances; this was called a “bulging ring”. Thus, the cytoplasmic bridge between erythroblasts did not morphologically correspond to the telophase bridge in the usual cytokinesis. Cytoplasmic bridges were observed in various differentiating stages of erythroblasts, whereas other cell types of the hemopoietic lineage did not have such a bridge. The cytoplasmic bridge is unique to erythroblasts and provides an evidence for the atypical cytokinesis of the erythroblastic lineage.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00313958
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  • 36
    Digitale Medien
    Digitale Medien
    Regulation of nuclear membrane assembly and maintenance during in vitro maturation of mouse oocytes: role of pyruvate and protein synthesis (1991)
    Springer
    Cell & tissue research 265 (1991), S. 105-112 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Oocytes ; Meiosis ; Energy metabolism ; Protein synthesis ; Nuclear envelope ; Electron microscopy ; Mouse (Swiss)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary In the absence of a suitable energy source, mouse oocytes cultured in vitro resume, but fail to complete, meiotic maturation. However, little is known about the underlying mechanisms leading to this meiotic failure. We utilized pyruvate-deficient medium to test for the role of pyruvate throughout the meiotic maturation process. Germinal vesicle-stage (GV) oocytes underwent germinal vesicle breakdown (GVBD), but failed to form a polar body when cultured continuously in pyruvate-free medium. However, when GV oocytes were preincubated for 4 h in pyruvate-free medium containing dibutyryl cyclic adenosine monophosphate (dbcAMP) and then cultured in pyruvate-free medium, GVBD was markedly inhibited. Preincubation of GV oocytes in dbcAMP and cycloheximide, followed by culture in cycloheximide only, also inhibited GVBD. A longer preincubation period was required in the cycloheximide-dbcAMP case (12 h) than in pyruvate-free-dbcAMP medium situation (4 h). Strikingly, reassembly of the nuclear membrane without polar body formation was observed following GVBD in oocytes continuously cultured in pyruvate-free medium. The reassembled nuclear membrane increased in size with continued culture, and it surrounded partially-decondensed chromatin. Nuclear membrane reassembly also occurred in oocytes which had undergone GVBD during continuous culture in medium containing only cycloheximide. Reformation of nuclear membranes after GVBD was confirmed by electron-microscopic analyses of oocytes cultured in pyruvate-free medium or in the presence of cycloheximide. We conclude that both pyruvate and protein synthesis are required for nuclear membrane disassembly, whereas lack of pyruvate or protein synthesis is associated with interruption of the metaphase state and reassembly of the nuclear membrane. The evidence suggests that assembly and maintenance of an intact nucleus and its disintegration are all amenable to regulation by pyruvate, possibly via mechanism(s) involving protein synthesis.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00318144
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  • 37
    Digitale Medien
    Digitale Medien
    Barrier membranes at the outer surface of the brain of an elasmobranch, Raja erinacea (1991)
    Springer
    Cell & tissue research 265 (1991), S. 113-120 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Blood-brain barrier ; Glia ; Meninges ; Electron microscopy ; Skate, Raja erinacea (Elasmobranchii)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary This report gives the results of the first electron-microscopic examination of the cell layers covering the outer brain surface and the inner surface of the cartilaginous skull in the skate, Raja erinacea. The perivascular glial blood-brain barrier — a characteristic of elasmobranchs — extends to the outer surface of the brain. This outer barrier layer is surrounded, in turn, by a subarachnoid compartment (depth: 30–40 μm), containing loose connective tissue and blood vessels; by an arachnoid-like epithelium (10–15 cell layers), impermeable to horseradish peroxidase; and, by perimeningeal fluid, a fluid with a slow turnover rate and a protein composition different from plasma. The inside of the skull, facing the perimeningeal fluid, is covered by a multilayered (10–15 layers) cuboidal epithelium, also impermeable to horseradish peroxidase. Closely apposed cells in the luminal layer of this epithelium have apical microvilli and numerous vesicular profiles, containing material of moderate electron density. These observations may explain, in terms of structure, the regulated protein content of perimeningeal fluid and the restricted exchange of solutes between brain and perimeningeal fluid in elasmobranchs.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00318145
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  • 38
    Digitale Medien
    Digitale Medien
    Structural heterogeneity of the basement membrane in the rat proximal tubule (1991)
    Springer
    Cell & tissue research 266 (1991), S. 11-22 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Basement membrane ; Proximal tubule ; Hydraulic pressure ; Mechanical stress ; Electron microscopy ; Rat (Sprague-Dawley)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The ultrastructure of the basement membrane of the rat proximal tubule was observed by transmission electron microscopy after the use of a cold dehydration technique. The basement membrane of the P1 segment is thick and possesses several structural specializations that are rare in other basement membranes; these include intraepithelial ridges, dense bars, and basement membrane vesicles. The intraepithelial ridges are found in the intercellular spaces between interdigitating processes of the proximal tubule cells. The ridges and the interdigitating processes run circumferentially around the tubule. The dense bars are frequently found in the intraepithelial ridges. They are especially prominent on the concave side of the tubular bends and to a lesser extent near sites where intracellular actin filaments anchor onto the basal cell membranes. The basement membrane vesicles are bounded by unit membranes; they are variable in both their electron density and their size. They are usually found in association with dense bars, and the grade of their accumulation is positively correlated with the development of the dense bars. These three specializations have no topographical relationship with the interstitial structures, such as fibrobalasts and collagen fibrils. The specializations are best developed on the concave side of tubular bends where the circumferential stresses caused by the intraluminal hydraulic pressure are presumably the largest; we therefore propose that they are an adaptation to, or a manifestation of, the increased wall stress in the proximal tubule.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00678706
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  • 39
    Digitale Medien
    Digitale Medien
    An immunocytochemical study of the endocrine pancreas in the Australian fat-tailed dunnart (Sminthopsis crassicaudata) (1991)
    Springer
    Cell & tissue research 263 (1991), S. 195-198 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Pancreas, endocrine ; Islets of Langerhans ; Immunocytochemistry ; Endocrine cells four types ; Electron microscopy ; Sminthopsis crassicaudata (Marsupialia)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The endocrine pancreas of the Australian fattailed dunnart, Sminthopsis crassicaudata, was investigated by means of electron-microscopic immunocytochemistry using the protein A-gold technique on London resin (LR) white-embedded tissue. The primary antibodies used were raised against insulin, glucagon, somatostatin and pancreatic polypeptide. The morphology of the secretory granules differed in the four cell types. The insulin cells are pleomorphic, and the secretory granules composed of an electron-dense core surrounded by an electron-lucen halo. The glucago cells possess granules with an electron-dense core usually surrounded by a halo of less dense granular material. Somatostatin cells have large, less dense secretory granules. The pancreatic polypeptide cells show small, dense secretory granules. In order for an ultrastructural study to be considered reliable for the definite identification of endocrine cell types, it is essential that it be corroborated by immunocytochemical data at the light-or preferably electron-microscopic level. Recent developments in immuno-electron-microscopic techniques have contributed to a better knowledge of cells responsible for the secretion of a wide variety of hormones, as in this study.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00318415
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  • 40
    Digitale Medien
    Digitale Medien
    Quantitative analysis of regional variability in the distribution of transverse tubules in rabbit myocardium (1991)
    Springer
    Cell & tissue research 264 (1991), S. 293-298 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Transverse (T-) tubules ; Muscle, cardiac ; Electron microscopy ; Morphometry ; Rabbit (Lagomorpha)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The goal of the present investigation was to compare quantitatively the distribution of T-tubules between regions of the myocardium. The volume fraction and surface density of T-tubules in rabbit right atrial free wall, left atrial free wall, right ventricular free wall, left ventricular free wall, right ventricular papillary muscle, and left ventricular papillary muscle were measured using established, electron-microscopic, morphometric techniques. T-tubules were delineated using wheat-germ agglutinin conjugated to horseradish peroxidase as a tracer. No significant differences were found in the morphometric parameters between any two ventricular samples or between atrial samples. Furthermore, little difference between T-tubule volume fraction or surface density was found between individual animals for any given site. Both volume fraction and surface density of ventricular T-tubules were more than ten-times their values in atrial tissue (volume fraction: 3.43%±0.35 vs. 0.20±0.09; surface density: 2.46 μm2/μm3±0.11 vs 0.10±0.04). Measurements show that there is greater variation of T-tubule volume fraction and surface density within atrial samples than within ventricular samples. This suggests greater inhomogeneity in T-tubule distribution in atrial myocardium than in ventricular myocardium. Morphometric data also indicate that the mean diameter of atrial T-tubules is greater than that of ventricular T-tubules while qualitative observations show that atrial T-tubules are distributed less regularly and have a larger longitudinal component to their organization than those in the ventricular myocardium.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00313966
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  • 41
    Digitale Medien
    Digitale Medien
    Nerve growth factor receptor-like immunoreactivity in primary and permanent canine tooth pulps of the cat (1991)
    Springer
    Cell & tissue research 264 (1991), S. 321-328 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Tooth pulp ; NGF receptor ; Calcitonin gene-related peptide ; Substance P ; Neuropeptide Y ; Immunocytochemistry ; Electron microscopy ; Cat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The distribution of nerve growth factor receptor (NGF receptor)-like immunoreactivity in pulps of developing primary and mature permanent cat canine teeth was examined, by use of a monoclonal antibody against NGF receptor detected by fluorescence immunohistochemistry and pre-embedding immunocytochemical light- and electron microscopy. Both primary and permanent pulps contained a vast number of NGF receptor-like immunoreactive nerves. Immunolabelling appeared to be localized both to axons and Schwann cells. In addition, many blood vessel walls in immature primary tooth pulps showed NGF receptor-like immunoreactivity, in contrast to permanent pulps where blood vessels rarely were NGF receptor-immunoreactive. Double-labelling immunofluorescence experiments revealed that in the permanent pulp a majority of the NGF receptor-positive nerves also showed calcitonin gene-related peptide (CGRP)-like immunoreactivity, and many showed substance P-like immunoreactivity. However, nerve fibers with neuropeptide Y-like immunoreactivity lacked NGF receptor-like immunoreactivity. In developing primary tooth pulps fewer NGF receptor-positive nerves were CGRP-like immunoreactive or substance P-like immunoreactive, as compared to the permanent pulp. Neuropeptide Y-like immunoreactive nerve fibers were not detected in the primary tooth pulp. The results suggest a role for nerve growth factor in both developing and mature sensory nerves of the tooth pulp.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00313969
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  • 42
    Digitale Medien
    Digitale Medien
    Effects of prolonged sodium restriction on the morphology and function of rat adrenocortical autotransplants (1991)
    Springer
    Cell & tissue research 265 (1991), S. 35-41 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Adrenal autotransplants ; Sodium restriction ; Mineralocorticoid hormones ; Electron microscopy ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Regenerated adrenocortical nodules were obtained by implanting fragments of the capsular tissue of excised adrenal glands into the musculus gracilis of rats (Belloni et al. 1990). Five months after the operation, operated rats showed a normal basal blood level of corticosterone, but a very low concentration of circulating aldosterone associated with a slightly increased plasma renin activity (PRA). Regenerated nodules were well encapsulated and some septa extended into the parenchyma from the connective-tissue capsule. The majority of parenchymal cells were similar to those of the zonae fasciculata and reticularis of the normal adrenal gland, while zona glomerulosa-like cells were exclusively located around septa (juxta-septal zone; JZ). In vitro studies demonstrated that nodules were functioning as far as glucocorticoid production was concerned, while mineralocorticoid yield was very low. Prolonged sodium restriction significantly increased PRA and plasma aldosterone concentration, and provoked a marked hypertrophy of JZ, which was due to increases in both the number and average volume of JZ cells. Accordingly, the in vitro basal production of aldosterone and other 18-hydroxylated steroids was notably enhanced. The plasma level of corticosterone, as well as zona fasciculata/reticularis-like cells and in vitro production of glucocorticoids by regenerated nodules were not affected. These findings, indicating that autotransplanted adrenocortical nodules respond to a prolonged sodium restriction similar to the normal adrenal glands, suggest that the relative deficit in mineralocorticoid production is not due to an intrinsic defect of the zona glomerulosa-like JZ, but is probably caused by the impairment of its adequate stimulation under basal conditions. The hypothesis is advanced that the lack of splanchnic nerve supply and chromaffin medullary tissue in regenerated nodules may be the cause of such an impairment.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00318136
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  • 43
    Digitale Medien
    Digitale Medien
    The endocrine pancreas of glucagon-and somatostatin-immunized rabbits (1991)
    Springer
    Cell & tissue research 265 (1991), S. 261-273 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Endocrine pancreas ; Immunization ; Insulin ; Glucagon ; Somatostatin ; Electron microscopy ; Rabbit (Chinchilla, Ch: b Ch)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary An active or passive immunization against hormones and the subsequent neutralization of hormones by circulating antibodies is a valuable tool for the identification of hormonal action. To recognize presumed local (autocrine, paracrine) effects exerted by pancreatic hormones, the endocrine pancreas of rabbits was investigated electron-microscopically after long-term immunization against glucagon or somatostatin. Glucagon immunization resulted in hyperplasia and hypertrophy of glucagon- (A-) cells and in their increased metabolic activities: They showed prominent nucleoli, increased amounts of endoplasmic reticulum, Golgi areas, and mitochondria. These changes were paralleled by alterations in secretion granules (increased size, decreased hormonal content), increased numbers of lysosomes (crinophagic bodies), and an increment of the filamentous system. Basically, these findings point to an autocrine regulation of A-cells. Following somatostatin immunization, somatostatin- (D-) cells were hyperplastic but unchanged in their metabolic state. Instead, insulin-(B-) cells and A-cells exhibited equivalents of increased cellular activities (parameters, see above). This stimulation most probably is caused by cancelled paracrine (inhibitory) effects of somatostatin. The changes observed after both immunizations were differently expressed in morphologically heterogeneous islet types (size, angioarchitecture, cellular composition, microtopology of the various cell types). It is concluded, therefore, that the regulation of islets is not uniform. Autocrine and paracrine effects exerted by islet hormones are of different significance in individual islets, or they interfere differently with other regulatory signals.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00398074
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  • 44
    Digitale Medien
    Digitale Medien
    Morphological and cytochemical studies of the effects of ecdysteroids in a lepidopteran cell line (IAL-PID2) (1991)
    Springer
    Cell & tissue research 265 (1991), S. 361-369 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Electron microscopy ; Scanning electron microscopy ; Lectin-gold particles ; Cytology ; Glycoproteins ; Imaginal discs ; Tissue culture ; Plodia interpunctella (Insecta)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The Indian meal-moth cell line, IAL-PID2, established from larval wing discs was examined from the 250th to the 300th passages. The cultured cells retain various structural and functional qualities of epidermal cells. Under hormone-free conditions PID2 cells grow as a monolayer of round or spindle-shaped cells. They appear as weakly active epidermal cells. The endoplasmic reticulum and Golgi apparatus are poorly developed and secretory activity is reduced. Culture conditions resulted in considerable cellular expansions, abundance of storage products (glycogen, lipids), and hypertrophy of the lysosomal system. The PID2 cell line retains the ability to respond to ecdysteroids; 20-hydroxyecdysone treatment (2×10-6 M) triggered morphogenetic and secretory processes. Cells formed pseudoepithelial aggregates interconnected and linked by desmosome-like structures. The hormone-stimulated cells are involved in the biosynthesis of N-acetyl-D-glucosamine-rich glycoproteins. The glycosylation sites were located, by use of WGA-gold particles, on cellular expansions and all along the plasma membrane. The possible significance of these glycoproteins is discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00398084
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  • 45
    Digitale Medien
    Digitale Medien
    Electron microscopic changes and edema after nine hours' perfusion of isolated canine hearts (1991)
    Springer
    Heart and vessels 6 (1991), S. 203-210 
    Details
    ISSN: 1615-2573
    Schlagwort(e): Isolated heart ; Extended perfusion ; Oxygen-carrying solutions ; Electron microscopy ; Preservation and edema
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract In a comparative study, we investigated whether or not removed and non-beating hearts could be preserved in vitro by continuous perfusion with oxygen-carrying solutions (blood, perfluoro-carbon emulsion) and simultaneous substitution with specific substrates. We used 18 mongrel dogs subdivided into 2 groups (1st group: perfluorocarbon emulsion; 2nd group: blood); the perfusion time was 9 h. In addition to parameters to control the medium of the perfusion solution, we measured parameters that would allow us to assess the success of the extended perfusion. These parameters were high-energy phosphates and, in particular, electron optical analysis. At the end of the perfusion period, electron optical analysis revealed a mild and reversible ischemic reaction by the myocardial cells in both groups. However, statistical analysis showed (1) a significant increase in the ischemic reaction for both groups over the perfusion period (P=0.02), and (2) a significant, even more pronounced ischemic reaction in the subendocardial myocardium (P=0.025). It should be noted that distinctly interstitial edema developed during the perfusion period and that this would appear to be a fairly critical problem with extended continuous isolated heart perfusion.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02125098
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  • 46
    Digitale Medien
    Digitale Medien
    Patterns of cortical and perinuclear microtubule organization in meristematic root cells ofAdiantum capillus veneris (1991)
    Springer
    Protoplasma 165 (1991), S. 173-188 
    Details
    ISSN: 1615-6102
    Schlagwort(e): Adiantum capillus veneris ; Meristematic root cells ; Microtubule organization ; Immunofluorescence microscopy ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The interphase meristematic root cells ofAdiantum capillus venerispossess a well developed cytoskeleton of cortical microtubules (Mts), which disappear at prophase. The preprophase-prophase cells display a well organized preprophase microtubule band (PMB) and a perinuclear Mt system. The observations favour the suggestion that the cell edges included in the PMB cortical zone possess a Mt organizing capacity and thus play an important role in PMB formation. The perinuclear Mts are probably organized on the nuclear surface. The preprophase-prophase nuclei often form protrusions towards the PMB cortical zone and the spindle poles, assuming a conical or rhomboid shape. Mts may be involved in this nuclear shaping. Reinstallation of cortical Mts in dividing cells begins about the middle of cytokinesis with the reappearance of short Mts on the cell surface. When cytokinesis terminates, numerous Mts line the postcytokinetic daughter wall. Many of them converge or form clusters in the cytoplasm occupying the junctions of the new and the old walls. In the examined fern, the cortical Mt arrays seem to be initiated in the cortex of post-cytokinetic root cells. A transitory radial perinuclear Mt array, comparable to that found in post-telophase root cells of flowering plants, was not observed inA. capillus veneris.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01322288
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  • 47
    Digitale Medien
    Digitale Medien
    Repair of 8-methoxypsoralen photoinduced cross-links in yeast (1991)
    Springer
    Molecular genetics and genomics 228 (1991), S. 335-344 
    Details
    ISSN: 1617-4623
    Schlagwort(e): Saccharomyces cerevisiae ; DNA interstrand cross-links ; DNA repair ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The repair of interstrand cross-links induced by 8-methoxypsoralen plus UVA (365 nm) radiation DNA was analyzed in diploid strains of the yeast Saccharomyces cerevisiae. The strains employed were the wild-type D7 and derivatives homozygous for the rad18-1 or the rad3-12 mutation. Alkaline step-elution and electron microscopy were performed to follow the process of induction and removal of photoinduced crosslinks. In accordance with previous reports, the D7 rad3-12 strain failed to remove the induced lesions and could not incise cross-links. The strain D7 rad18-1 was nearly as efficient in the removal of 8-MOP photoadducts after 2 h of post-treatment incubation as the D7 RAD+ wild-type strain. However, as demonstrated by alkaline step-elution and electron microscopic analysis, the first incision step at DNA cross-links was three times more effective in D7 rad18-1 than in D7 RAD+. This is consistent with the hypothesis that the RAD18 gene product is involved in the filling of gaps resulting from persistent non-informational DNA lesions generated by the endonucleolytic processing of DNA cross-links. Absence of this gene product may lead to extensive strand breakage and decreased recognition of such lesions by structural repair systems.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00260625
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  • 48
    Digitale Medien
    Digitale Medien
    Mechanism of the damage to myelinated axons in experimental Creutzfeldt-Jakob disease in mice: An ultrastructural study (1991)
    Springer
    European journal of epidemiology 7 (1991), S. 545-550 
    Details
    ISSN: 1573-7284
    Schlagwort(e): Creutzfeldt-Jakob disease ; Electron microscopy ; Myelinated axon
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract We report the ultrastructural pathology of myelinated axons in mice infected experimentally with the Fujisaki strain of Creutzfeldt-Jakob disease (CJD). Initially the myelin sheath was separated into several concentric bands, and cellular processes penetrated between layers of myelin and lifted away the outermost lamella. Then a complicated labyrinth of the concentric cellular processes, clearly belonging to either astrocytes or macrophages, invested myelinated axons. In terminal stages axons completely denuded of myelin were seen in the center of concentric networks of cellular processes. Myelin remnants were seen within astrocytes and macrophages. We conclude that the mechanism(s) of damage to myelinated axons in CID may be similar to that operating in immunologically mediated demyelinating disorders.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00143137
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  • 49
    Digitale Medien
    Digitale Medien
    Merkel cell carcinoma of the head and neck associated with Bowen's disease (1991)
    Springer
    European archives of oto-rhino-laryngology and head & neck 248 (1991), S. 436-441 
    Details
    ISSN: 1434-4726
    Schlagwort(e): Merkel cell carcinoma ; Neuroendocrine carcinoma ; Bowen's disease ; Immunohistochemistry ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The Merkel cell carcinoma occurs primarily in the skin of the head and neck, and develops in the dermis with a trabecular growth pattern. Immunohistochemistry reveals positive staining for neuron-specific enolase, neurofilaments, cytokeratin and chromogranin A. Electron microscopically, the tumor cells contain dense-core granules, spinous cytoplasmic processes, desmosomes, zonulae adherentes and paranuclear filament aggregates besides frequent mitoses, focal necroses and lymphocyte and plasma cell infiltrates. The Merkel cell carcinoma is often co-existent with other malignancies such as squamous cell carcinoma or, as in the present study, with Bowen's disease. The definite diagnosis of the Merkel cell carcinoma can be effected only by electron microscopic examination of the tumor.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00627629
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  • 50
    Digitale Medien
    Digitale Medien
    Determination of vesicle size distributions by freeze-fracture electron microscopy (1991)
    New York, NY : Wiley-Blackwell
    Journal of Electron Microscopy Technique 17 (1991), S. 459-466 
    Details
    ISSN: 0741-0581
    Schlagwort(e): Vesicle ; Freeze-fracture ; Electron microscopy ; Size distributions ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Allgemeine Naturwissenschaft
    Notizen: The most common electron microscopic technique for obtaining information on size distributions of uncollapsed membrane vesicles is based on the method of van Venetie (1980). This technique involves the sizing of only those vesicles that were freeze fractured at their equatorial planes. As a result, only a small number of images can be used to generate size distributions. Further, the technique is susceptible to systematic error. An alternate approach is to consider the complete distribution of image sizes and use this distribution to determine the average size and distribution of the vesicles. It is shown that the mean vesicle size is 4/π times the mean image size. As well, a parameter, m, which can be determined from the image distribution, can be used to characterize the vesicle distribution. The advantage of this new approach is that images of all vesicles are used, leading to a statistically better determination of vesicle sizes.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jemt.1060170409
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  • 51
    Digitale Medien
    Digitale Medien
    Ultrastructural investigation of neurons identified and localized using the confocal scanning laser microscope (1991)
    New York, NY : Wiley-Blackwell
    Journal of Electron Microscopy Technique 18 (1991), S. 82-90 
    Details
    ISSN: 0741-0581
    Schlagwort(e): Biocytin ; Electron microscopy ; Diaminobenzidine ; Hippocampus ; Horseradish peroxidase ; Spines ; Varicosities ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Allgemeine Naturwissenschaft
    Notizen: Studies of labeled neurons at the light-microscopic level often pinpoint a substructure of particular interest, i.e., a synapse or a spine. An ultrastructural investigation would explain a lot about how these structures arose, how they function, and how they are regulated. Finding a small region in a large block can require constant checking during sectioning, until past the structure. In our pursuit of the synaptic structure of varicosities on the axons of neurons identified physiologically and morphologically at the light level, we have combined confocal scanning laser microscopy (CSLM) with conventional and high-voltage electron microscopy (EM). CSLM images were collected in the reflection mode to view neurons filled with horseradish peroxidase and stained with nickel-intensified diaminobenzidine, which is compatible with EM. The CSLM optical sections provided a record of what one should expect to see at regular intervals throughout the depth of the tissue block. We have shown that the CSLM greatly simplified the task of localizing small structures in brain tissue prepared for EM.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jemt.1060180112
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  • 52
    Digitale Medien
    Digitale Medien
    Ultrastructural cryoimmunocytochemistry is a convenient tool for the study of DNA replication in cultured cells (1991)
    New York, NY : Wiley-Blackwell
    Journal of Electron Microscopy Technique 18 (1991), S. 91-105 
    Details
    ISSN: 0741-0581
    Schlagwort(e): BrdU incorporation ; Cultured cells DNA replication ; Electron microscopy ; EM immunocytochemistry ; Immunocytochemistry ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Allgemeine Naturwissenschaft
    Notizen: In the present study, we have optimized an immunocytochemical ultrastructural approach for in situ localization of newly synthesized DNA in unsynchronized as well as in synchronized human HeLa cells and in exponentially growing mouse P815 cells, which had incorporated bromodeoxyuridine (BrdU) during short pulses varying from 1 to 20 minues. The incorporated BrdU was detected in hydrolyzed ultrathin cryosections or Lowicryl sections by means of a monoclonal antibody, revealed by secondary colloidal gold-labeled probes. The results demonstrate our ability to study, with high resolution and reproducibility, DNA replication during consecutive periods of the S-phase, which is monitored by the incorporation of tritiated thymidine. In addition, this approach allows one to perform a concomitant mapping of replicated DNA and various enzymes of the replisome.
    Zusätzliches Material: 14 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jemt.1060180202
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  • 53
    Digitale Medien
    Digitale Medien
    Ultrastructure of the seminiferous epithelium and intertubular tissue of the human testis (1991)
    New York, NY : Wiley-Blackwell
    Journal of Electron Microscopy Technique 19 (1991), S. 215-240 
    Details
    ISSN: 0741-0581
    Schlagwort(e): Spermatogenesis ; Sertoli cells ; Leydig cells ; Electron microscopy ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Allgemeine Naturwissenschaft
    Notizen: The ultrastructural features of the human testis are reviewed with emphasis upon the process of spermatogenesis and the cytology of the Leydig cells. The seminiferous epithelium is structurally partitioned by the Sertoli cells into basal and adluminal compartments via the specialized tight junctions between the Sertoli cells. Spermatogonia reside in the basal compartment, and, via a series of cell divisions, produce the primary spermatocytes, which at the commencement of their development move into the adluminal compartment, and thus the lengthy process of meiotic maturation is initiated. The fine structure of primary spermatocytes is described together with the complex transformation of the spermatids into spermatozoa during the process of spermiogenesis. Earlier studies of the organization of the human seminiferous epithelium showed that germ cells at different developmental stages formed identifiable collections termed cell associations or stages, but since several stages were seen in a single tubule cross-section, this gave the impression of an extremely irregular pattern of spermatogenic development. When the topographic arrangement of germ cells was re-examined with the aid of computer modelling, a highly ordered distribution was revealed, conforming to a helical pattern based on the geometry of spirals. Thus spermatogenesis in the human testis is subjected to a precise regulation in keeping with the ordered arrangement of the germ cells seen in other mammalian species. The intertubular tissue of the human testis is composed of loose connective tissue containing blood vessels, occasional lymph capillaries, macro-phages, mast cells, and the Leydig cells which occur either as single cells or form small clusters. The Leydig cell cytoplasm contains an abundant supply of smooth endoplasmic reticulum and mitochondria with tubular cristae, both features being characteristic of steroidogenic cells. Human Leydig cells contain large Reinke crystalloids of variable size and number, but their function remains obscure. The frequent occurrence of paracrystalline inclusions within the cytoplasm of the human Leydig cell suggests that these elements are precursors of the Reinke crystalloids.
    Zusätzliches Material: 19 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jemt.1060190208
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  • 54
    Digitale Medien
    Digitale Medien
    Image analysis of mineralized and non-mineralized type I collagen fibrils (1991)
    New York, NY : Wiley-Blackwell
    Journal of Electron Microscopy Technique 18 (1991), S. 262-268 
    Details
    ISSN: 0741-0581
    Schlagwort(e): Collagen ; Mineral ; Calcification ; Tendon ; Electron microscopy ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Allgemeine Naturwissenschaft
    Notizen: Turkey leg tendons at an early stage of mineralization have been thin sectioned and imaged by electron microscopy. At this stage collagen-associated mineral apatite was found to be present within both the gap and overlap zones. The earliest apatite occurs in a microcrystalline form which gives a rather generalized and characteristic density to both the gap and overlap zones; with subsequent development larger defined apatite crystals arise which span gap/overlap zones. Fourier transformation of such images revealed the major 67 nm axial repeat of the gap/overlap zone plus four other maxima corresponding to repeat spacings of 22, 16, 13, and 11 nm respectively. Computer imaging techniques were used to reconstruct images by using selected spatial frequencies from such transforms. In this manner the subperiodic distributions of mineral were visually enhanced. These subperiodicities are positioned in an asymmetric fashion over the entire D unit repeat aligning with the molecular orientation of the fibril. Analyses of both negatively stained collagen and computer-generated maps of collagen hydrophobicity were compared to the mineral distribution of collagen. Densitometric comparisons showed a positional correlation between the axial banding patterns of mineralized fibrils and those of negatively stained non-mineralized fibrils. Comparable spatial frequencies were also present in transforms between hydrophobic maps and mineral distribution of collagen. These results suggest that the lateral clusterings of hydrophobic residues which span the fibril at specific sites in both the gap and overlap zones serve to prohibit early mineral deposition. This observed hydrophobic influence in combination with the gap space appear as contributing factors in the observed axial distribution of mineral within collagen.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jemt.1060180308
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  • 55
    Digitale Medien
    Digitale Medien
    Ultrastructural localization of defined sequences of viral RNA and DNA by in situ hybridization of biotinylated DNA probes on sections of herpes simplex virus type 1 infected cells (1991)
    New York, NY : Wiley-Blackwell
    Journal of Electron Microscopy Technique 18 (1991), S. 336-353 
    Details
    ISSN: 0741-0581
    Schlagwort(e): Electron microscopy ; Lowicryl ; Herpes simplex virus type 1 infection ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Allgemeine Naturwissenschaft
    Notizen: The influence of fixation and enzymatic digestions on the ability of a denatured double-stranded DNA probe to bind specifically to related sequences of RNA and DNA in sections of Lowicryl embedded cells was investigated. Specificity of the hybridization was assessed using a biotinylated cloned subgenomic herpes simplex virus type 1 DNA fragment to localize viral nucleic acids in sections of infected cells. The probe was detected by anti-biotin antibodies and indirect immunogold labeling. Controls indicated that protease digestion of proteins from the section eliminated non-specific binding of the probe and labeling of endogenous biotin.Both formaldehyde and glutaraldehyde fixation retained viral RNA in protease digested sections. Its labeling was randomly and sparsely distributed over the fibrillo-granular network of the infected nucleus and over the ribosome-rich regions of cytoplasm.Labeling of single-stranded portions of viral DNA in protease-RNase digested sections was infrequent. It was located precisely over nucleoids of a few viral nucleocapsids whatever their location in the cell and their stage of maturation.Labeling of double-stranded viral DNA by denaturation of the DNA in the sections of Lowicryl embedded cells was possible after fixation with formaldehyde but not glutaraldehyde. Among several denaturation protocols, 0.5 N NaOH treatment was best for hybridization of both nonencapsidated and encapsidated viral DNA in protease-RNase digested sections. Free viral genomes were detected exclusively within the virus-replicating region of infected nuclei. Labeling of viral nucleoids was independent of their location in the cell. The high percentage of labeled viral nucleoids suggests that the related viral DNA sequence is not aggregated in the nucleoid but is extended and therefore numerous portions of this defined DNA sequence are accessible at the surface of the section for the binding of the probe.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jemt.1060180403
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  • 56
    Digitale Medien
    Digitale Medien
    Interrelationships of ultrastructure and function in the microvasculature of normal and ischaemic myocardium (1991)
    New York, NY : Wiley-Blackwell
    Journal of Electron Microscopy Technique 19 (1991), S. 429-438 
    Details
    ISSN: 0741-0581
    Schlagwort(e): Myocardium ; Blood vessels ; Electron microscopy ; Fixation ; Methods ; Ischaemia ; Reperfusion ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Allgemeine Naturwissenschaft
    Notizen: This paper reviews various methods involving electron microscopy that have been used to investigate the ultrastructure of the vasculature of the normal and diseased heart. Whereas scanning electron microscopy is more commonly employed to record surface topography, it can be used to examine freeze-fracture planes within the myocardium and, using heavy-metal staining and back-scattered electron imaging, to examine large 2-μ-thick resin-embedded sections through the heart. The latter technique allows the comparison of structural alterations across the wall of the heart and thus accurate definition of the transmural progression of pathological processes. Transmission electron microscopy can then be used to provide more detailed information from precisely localised regions. Human myocardium can be usefully studied up to 12 hours post-mortem provided that suitable control material is included. Intravascular tracers including low-viscosity resin and nuclear track emulsion can be used to determine whether or not particular vessels allow flow at the time of fixation, and thus changes in the pattern of flow through the microvasculature due to ischaemia and reperfusion can be quantified and defined. Particular care is required in the fixation of ischaemic tissues because oxygen dissolved in the fixative can lead to the rapid formation of oxygen-free radicals on contact with the tissue. This produces artefactual reoxygenation damage characterised by membrane disruption and cell and organelle swelling, which has previously been attributed to ischaemic injury per se. Bubbling glutaraldehyde with nitrogen substantially reduces this artefact.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jemt.1060190405
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  • 57
    Digitale Medien
    Digitale Medien
    Ultrastructure of spontaneous and transplanted pituitary tumors in laboratory animals (1991)
    New York, NY : Wiley-Blackwell
    Journal of Electron Microscopy Technique 19 (1991), S. 64-79 
    Details
    ISSN: 0741-0581
    Schlagwort(e): Immunocytochemistry ; Electron microscopy ; In situ hybridization ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Allgemeine Naturwissenschaft
    Notizen: The present review examines ultrastructural studies of pituitary tumors in laboratory animals. Such studies have been facilitated by the development of newer techniques such as immunocytochemistry and in situ hybridization. Using these methods it has been possible to correlate morphological features with function by characterizing specific pituitary hormones in secretory granules and analyzing the messenger ribonucleic acids produced by specific cell types. Analyses of spontaneous and experimentally induced tumors have provided a great deal of insight into the function and ultrastructure of these neoplasms. The description of tumor cells producing more than one hormone has been facilitated by immunocytochemical analyses. Studies of transgenic models of pituitary hyperplasia and tumor development are expanding our knowledge about the ultrastructure and about other aspects of pituitary tumors in a more controlled experimental setting. The production of various hormones by the same pituitary tumors and even the same tumor cells indicates that complex regulatory mechanisms must be analyzed by a combination of ultrastructural and other techniques to learn more about growth and hormone secretion in pituitary neoplasms.
    Zusätzliches Material: 13 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jemt.1060190107
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  • 58
    Digitale Medien
    Digitale Medien
    Lectin and immunolabeling of microvascular endothelia (1991)
    New York, NY : Wiley-Blackwell
    Journal of Electron Microscopy Technique 19 (1991), S. 305-315 
    Details
    ISSN: 0741-0581
    Schlagwort(e): Endothelium ; Immunocytochemistry ; Electron microscopy ; Lectins ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Allgemeine Naturwissenschaft
    Notizen: A number of recently developed localization techniques are beginning to be applied in the study of endothelial cells and their structural components. In this article we will review a number of these cytochemical approaches as well as their advantages and disadvantages and their applications. The methods will be presented for processing tissues for either L.R. White embedding or semi-thin and thin frozen sections followed by subsequent lectin and immunolabeling for fluorescence and electron microscopic examination. These techniques are easily applied in the localization of perfused exogenous proteins and of endogenous endothelial-associated proteins. The results that can be obtained from such studies are presented and discussed.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jemt.1060190306
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  • 59
    Digitale Medien
    Digitale Medien
    An easy method for orientated embedding tissue culture cell monolayers in LR white resin for postembedding immunocytochemistry (1991)
    New York, NY : Wiley-Blackwell
    Journal of Electron Microscopy Technique 17 (1991), S. 456-458 
    Details
    ISSN: 0741-0581
    Schlagwort(e): Electron microscopy ; Flat embedding ; Cell culture monolayers ; Ultramicrotomy section plane ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Allgemeine Naturwissenschaft
    Notizen: Partial polymerization of LR White resin blocks is a frequently encountered problem if oxygen is present during the polymerization reaction. Instructions are given for a simple method to embed cell culture monolayer in LR White acrylic resin, which is suitable for immunocytochemistry. The advantage of this method is that it is easy and reliable. It also ensures accurate orientation of the cell monolayer in relation to the desired plane of sectioning.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jemt.1060170408
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  • 60
    Digitale Medien
    Digitale Medien
    Histopathology of otitis media with effusion (1986)
    Springer
    European archives of oto-rhino-laryngology and head & neck 243 (1986), S. 269-273 
    Details
    ISSN: 1434-4726
    Schlagwort(e): Otitis media with effusion ; Electron microscopy ; Human temporal bones
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Ultrastructural studies of the middle ear mucosa appear to be of significant value in better understanding the pathology of otitis media with effusion (OME). Our present study was undertaken in order to take advantage of the use of electron microscopy in investigating all areas of the middle ear mucosa. Tissues studied were obtained from the fresh postmortem temporal bones of three patients with OME and terminal head and neck malignancies. In the mucoid type of effusion (cases 1 and 2), goblet cells were seen to proliferate and secretory activity was greatly enhanced. In contrast, there was no evidence of secretory cell proliferation in the serous type of effusion. It was noteworthy that accumulated fluid was not homogeneous in the same ear, as exemplified by case 1, in which both mucoid and serous effusions were present. This occurrence was possibly the result of topographic diversity involving the secretory activity of the middle ear.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00464444
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  • 61
    Digitale Medien
    Digitale Medien
    Experimental tympanosclerosis following infection with Streptococcus pyogenes and vitamin D3 intoxication (1986)
    Springer
    European archives of oto-rhino-laryngology and head & neck 243 (1986), S. 296-303 
    Details
    ISSN: 1434-4726
    Schlagwort(e): Experimental tympanosclerosis ; Induced calcifications ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary A rat animal model was used to study the ultrastructure of submucosal calcifications induced in the middle ear following inoculation with Streptococcus pyogenes and high doses of parenteral vitamin D3. The morphological changes present in affected animals resembled the classical picture of tympanosclerosis. While calcification occurred about bacterial remnants and myelin structures, the most important calcification centers were lysosomal and non-lysosomal matrix vesicles in the extracellular spaces. These formed band-like calcifications close to the basal membrane without affecting the epithelial layer. This animal model offers the possibility of studying the effect of various therapeutic regimens in the treatment of the dynamic tympanosclerotic process.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00460205
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  • 62
    Digitale Medien
    Digitale Medien
    Heterogeneity of circular mitochondrial DNA molecules from sugar beet with normal and male sterile cytoplasms (1986)
    Springer
    Current genetics 10 (1986), S. 695-700 
    Details
    ISSN: 1432-0983
    Schlagwort(e): Sugar beet ; Cytoplasmic male sterility ; Mitochondrial DNA ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Mitochondrial (mt) DNAs from normal (N) and male sterile (S) cytoplasms of sugar been have been isolated and investigated by electron microscopy. The results showed that mtDNA was composed of a heterogeneous population of circular molecules. Their contour lengths varied from 0.28 to 51 μm, but unlike in the case of maize, a large difference was not observed in the distribution of molecular classes greater than 1.0 μm between N and S cytoplasms of sugar beet. On the other hand, N and S cytoplasms were shown to contain their own characteristic combinations of small circular mtDNA species with lengths between 0.28 μm and 0.6 μm. Mitochondrial DNAs from various sources of male-sterile cytoplasms were analyzed by agarose gel electrophoresis to determine the extent of cytoplasmic variation. Additional low molecular weight DNA bands appeared in all male-sterile lines examined, and as a result, three distinctive banding patterns were recognized. These data are in general agreement with those based upon restriction endonuclease digestion of mt and chloroplast DNAs and the genetic analysis of fertility restoration in test crosses.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00410918
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  • 63
    Digitale Medien
    Digitale Medien
    Alpha-subunit-producing pituitary adenomas (1986)
    Springer
    Virchows Archiv 409 (1986), S. 417-431 
    Details
    ISSN: 1432-2307
    Schlagwort(e): Pituitary neoplasms ; Pituitary hormones ; Immunocytochemistry ; Electron microscopy ; Alpha-subunit ; Acromegaly
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Immunohistological techniques demonstrate the alpha-subunit of glycoprotein hormones in the majority of endocrine-inactive, undifferentiated pituitary adenomas and pituitary oncocytomas. In about one-fifth of endocrine-active adenomas, the alpha-subunit is produced in combination with either adrenocorticotropic hormone or prolactin, and it is found in combination with growth hormone in about half of those adenomas causing acromegaly. Pure alpha-subunit-producing, endocrine-inactive adenomas characteristically have small secretory granules that are destroyed by direct osmium fixation, but are well preserved after prefixation with glutaraldehyde. As only a few atypical prolactinomas show similar secretory granules, and as they display a positive reaction for the alpha-subunit only exceptionally, this ultrastructural feature can serve as a guide to differentiate such adenomas.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00705414
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  • 64
    Digitale Medien
    Digitale Medien
    Frequency and diagnostic value of the virus-like filamentous intranuclear inclusions in giant cell tumor of bone, not associated with Paget's disease (1986)
    Springer
    Virchows Archiv 410 (1986), S. 65-68 
    Details
    ISSN: 1432-2307
    Schlagwort(e): Giant-cell ; Virus-like inclusion ; Intranuclear inclusion ; Giant cell tumour of bone ; Paget's disease of bone ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary This paper deals with the paramyxovirus-like intranuclear inclusions observed in giant cells tumours of bone (GCTB). Twenty-one (49%) of 43 cases of GCTB (1977–1985), either fresh and/ or cultured, show these ultrastructural inclusions. Fifty samples of various bone lesions in which giant cell lesions occurred, including aneurysmal cysts, hyperparathyroidism, osteoblastoma, human and rat osteopetrosis, GCT of tendon sheaths, and non skeletal granuloma were used as controls. These, together with 20 samples of normal bone (osteoclasts) did not contain intranuclear or intracytoplasmic viral inclusions.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00710907
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  • 65
    Digitale Medien
    Digitale Medien
    Effects of experimental torsion of the spermatic cord on Leydig cell function in the guinea pig testis: An ultrastructural stereological analysis (1986)
    Springer
    Urological research 14 (1986), S. 253-256 
    Details
    ISSN: 1434-0879
    Schlagwort(e): Guinea pig ; Spermatic cord torsion ; Stereology ; Electron microscopy ; Leydig cell
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary An ultrastructural stereological analysis of Leydig cells of the guinea pig testis was carried out following surgically induced testicular torsion. Morphometric analyses of the Leydig cells of the experimental group of animals revealed an increase in the nucelar and mitochondrial volume and a decrease in the lipid volume, in comparison to those in the Leydig cells of the control group of animals. We believe that these changes in the Leydig cells of the experimental group of animals are indicative of cellular hypertrophy. The possible mechanisms of the Leydig cell hypertrophy in the guinea pig testis following the induction of spermatic cord torsion are discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00256568
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  • 66
    Digitale Medien
    Digitale Medien
    Ultrastructural abnormalities in muscular vessels of hyperthyroid patients (1986)
    Springer
    Acta neuropathologica 71 (1986), S. 64-69 
    Details
    ISSN: 1432-0533
    Schlagwort(e): Muscular diseases ; Capillar pathology ; Grave's disease ; Hyperthyroidism ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary an electron microscope study of needle biopsies from the quadriceps muscle was carried out in 11 non=selected patients (ten females and one male), with clinically and laboratory-diagnosed hyperthyroid disease. Alterations of the normal structure of muscle fibres were found in all cases. Changes in capillaries were found in ten patients, and ranged from an increase in basement membrane thickness with reduplication, to total destruction of the capillaries. The importance of the vascular involvement in the muscles of patients with Graves-Basedow disease is stressed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00687963
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  • 67
    Digitale Medien
    Digitale Medien
    Proliferating potential of folliculo-stellate cells in human pituitary adenomas (1986)
    Springer
    Acta neuropathologica 71 (1986), S. 233-242 
    Details
    ISSN: 1432-0533
    Schlagwort(e): Folliculo-stellate cell ; Pituitary adenoma ; Glial fibrillary acidic protein ; S-100 protein ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Folliculo-stellate cells (FS cells) in 40 pituitary adenomas and portions of anterior pituitary adjacent to the tumor in 26 cases were investigated immunohistochemically, using polyclonal antisera to S-100 protein (S-100) and glial fibrillary acidic protein (GFAP). The objective was to clarify the histological behavior of the FS cells. In most pituitary adenomas there were few or no S-100-or GFAP-positive cell, in comparison with numerous positive cells in the parts of the adenohypophyses compressed by adenomas. However, positive FS cells were observed in some types of pituitary adenomas. Growth hormone and prolactin producing adenomas frequently contained significant amounts of FS cells. In non-functioning adenomas, an unique case of FS cell adenoma was present. The adenoma was composed mainly of FS cells and immature glandular cells. The FS cells were sometimes located around follicles containing Periodic acid Schiff-positive material. Therefore, the FS cell adenoma is characterized by S-100- and GFAP-positive FS cells and PAS-positive follicles. In this type of adenoma, FS cells seemed to be the main proliferating component. In parts of the adenohypophyses adjacent to the adenomas, GFAP0-positive FS cells were numerous. In the pathological conditions FS cells may possess the potential of reactive proliferation.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00688045
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  • 68
    Digitale Medien
    Digitale Medien
    The distribution of Ia antigen in the lesions of rat acute experimental allergic encephalomyelitis (1986)
    Springer
    Acta neuropathologica 70 (1986), S. 149-160 
    Details
    ISSN: 1432-0533
    Schlagwort(e): Ia antigen ; Central nervous system ; Experimental allergic encephalitis ; Immunohistochemistry ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Ia antigen, encoded within the major histocompatibility complex, plays an important role in the activation of T lymphocytes. Since experimental allergic encephalitis is an essentially T cell-mediated disease, Ia antigen in the central nervous system (CNS) may be pathogenetically relevant. The occurrence of Ia antigen in the CNS of normal rats and of rats with experimental allergic encephalitis was studied by light and electron microscope immunocytochemistry using the monoclonal anti-Ia antibodies Ox 4 and Ox 6. In normal, unsensitized animals a distict population of stellate cells in the meninges and some perivascular mononuclear cells in the nervous tissue carried Ia antigen. In rats with experimental allergic encephalitis a dramatic increase of Ia-positive cells was found. In addition to the positive cells found in normal animals, monocytes, macrophages and many lymphocytes in the meningeal perivascular and parenchymal inflammatory infiltrates as well as “activated microglia” stained for Ia antigen. We did not find evidence for Ia expression on endothelial cells, astrocytes or other components of the CNS in either normal or diseased rats.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00691433
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  • 69
    Digitale Medien
    Digitale Medien
    Transplantation of Pacinian corpuscles of the rat into the brain (1986)
    Springer
    Acta neuropathologica 69 (1986), S. 314-321 
    Details
    ISSN: 1432-0533
    Schlagwort(e): Pacinian corpuscles ; Transplantation to the brain ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary In adult inbred rats of the AVN strain, branches of the crural interosseous nerve were dissected out from donors and transplanted into the brain of recipients, together with a cluster of Pacinian corpuscles, (either into a suction cavity or the cerebral cortex) into a slit 1–2 mm deep. The grafts were fixed and processed for electron microscopy 10 days to 6 months after the operation, and their ultrastructure was examined. Sporadic axons of small diameter grew into the nerve branches of some of the grafts from 11 days onward, and became myelinated during the 2nd month after the operation, but none of the transplanted Pacinian corpuscles became reinnervated. The corpuscles, however, survived denervation and grafting. Most of them retained a well-preserved inner core and an intact capsule, consisting of a normal complement of 29.2±1.0 (mean ±SE) capsular layers (n=8), as did the corpuscles previously examined after denervation in situ. Some of the corpuscles underwent degenerative changes, presumably due to a delayed or restricted revascularization. In this group of corpuscles, the inner core underwent disintegration and was gradually replaced by collagen fibrils, whereas the capsule remained preserved but the number of its layers eventually reduced by 40%. It is assumed that the lack of reinnervation of the grafted Pacinian corpuscles was due to the paucity of regenerating axons, and their failure to form correct projections along those Schwann cell columns connected with the corpuscles.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00688310
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  • 70
    Digitale Medien
    Digitale Medien
    Intercellular deposits of basement membrane material in active human pituitary adenomas detected by immunostaining for laminin and electron microscopy (1986)
    Springer
    Acta neuropathologica 71 (1986), S. 326-331 
    Details
    ISSN: 1432-0533
    Schlagwort(e): Pituitary adenoma ; Basement membrane ; Laminin ; Immunohistochemistry ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Thirty-eight human pituitary adenomas (24 endocrine active and 14 endocrine inactive tumors) were studied immunohistochemically for the presence of the basement membrane component, laminin, and ultrastructurally for the presence of basement membrane. Immunoreactivity of laminin delineated staining of epithelial and endothelial basement membranes, the reaction product being confined mostly to the perivascular zones. Moreover, a hitherto undescribed presence of intercellular laminin-positive droplets was observed in ten of the active adenomas (nine patients with hyperprolactinemia and/or acromegalia and one patient with Cushing's syndrome). Concurrently, at the ultrastructural level, bunches of basement membrane-like material intermingled between the adenoma cells were demonstrated in seven of these ten active adenomas. Furthermore, secretory granules were entrapped occasionally in this intercellular matrix, indicating a mutual dependence between excessive hormone extrusion and an increase of “misplaced” deposits of basement membrane components, e.g., laminin.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00688057
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  • 71
    Digitale Medien
    Digitale Medien
    Astroblastoma revisited: A report of three cases (1986)
    Springer
    Acta neuropathologica 70 (1986), S. 10-16 
    Details
    ISSN: 1432-0533
    Schlagwort(e): Astroblastoma ; Immunohistopathology ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The very existence of astroblastoma has been a question of considerable controversy, although there appears now to be sufficient documentation to establish it as a tenable entity. Due to the rarity of this tumor, little information exists in the literature as to its natural history, efficacy of therapy and its pathological and radiological appearance. We report three cases of astroblastoma, describing their natural history, the response to therapeutic interventions and their light microscopic, ultrastructural and immunohistochemical characteristics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00689508
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  • 72
    Digitale Medien
    Digitale Medien
    Ultrastructural localization of S-100 protein in neurofibroma (1986)
    Springer
    Acta neuropathologica 69 (1986), S. 103-110 
    Details
    ISSN: 1432-0533
    Schlagwort(e): Neurofibroma ; von Recklinghausen's disease ; S-100 protein ; Electron microscopy ; Immunoelectron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The nature of the cells in neurofibromas was studied by electron microscopy and immunoelectron-microscopic examination of S-100 protein. Ultrastructurally, all five neurofibromas studied were found to be composed of Schwann cells, perineurial cells, and intermediate cells, which had features of both perineurial cells and fibroblasts. The Schwann cells had complex, branched cytoplasmic processes and a continuous basal lamina. The perineurial cells were distinguishable from Schwann cells by the presence of numerous pinocytotic vesicles, unbranched slender cytoplasmic processes and a discontinuous basal lamina. The intermediate cells had no basal lamina, but were topographically related to Schwann cells and had a similar fine structure to that of perineurial cells. Thus, they seemed to be modified neoplastic perineurial cells. Immunoelectron-microscopic studies showed the presence of cells with and without S-100 protein in the neurofibromas: cells with S-100 protein resembled Schwann cells ultrastructurally, and those without S-100 protein were perineurial and intermediate cells. Some Schwann cells with S-100 protein in one neurofibroma had numerous pinocytotic vesicles characteristic of perineurial cells, suggesting that Schwann cells and perineurial cells, are functional variants of the same cell type. Thus this study showed that neurofibromas were composed of Schwann cells with S-100 protein and perineurial and intermediate cells, including socalled endoneurial fibroblasts, without S-100 protein. Morphological and functional transition seems to occur between Schwann cells and perineurial cells, and between perineurial cells and intermediate cells.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00687045
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  • 73
    Digitale Medien
    Digitale Medien
    Farber's disease in two siblings, sural nerve and subcutaneous biopsies by light and electron microscopy (1986)
    Springer
    Acta neuropathologica 72 (1986), S. 178-188 
    Details
    ISSN: 1432-0533
    Schlagwort(e): Farber's disease ; Peripheral nerve ; Subcutaneous nodules ; Electron microscopy ; Ceramidase deficiency
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Two siblings born from consanguineous tunisian parents are reported. They showed a severe form of Farber's disease with prominent involvement of the central and peripheral nervous system: low conduction velocity was noticed in both children. Macular cherry red spots were observed in one of them. The diagnosis for the girl investigated was confirmed by evidence of ceramidase deficiency in cultured fibroblasts. Here we report the pathological findings in the subcutaneous nodules using light and electron microscopy (one case), and in sural nerves using morphometric studies (both cases). Varying morphological aspects of intracellular inclusions, depending on the tissues involved, are described and discussed. A review of all cases reported since Farber's first paper in 1952 is given.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00685981
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  • 74
    Digitale Medien
    Digitale Medien
    Minisegments of newborn rat optic nerves in vitro: gliogenesis and myelination (1986)
    Springer
    Experimental brain research 65 (1986), S. 189-199 
    Details
    ISSN: 1432-1106
    Schlagwort(e): Rat optic nerve ; Gliogenesis ; Myelination ; In vitro ; In vivo ; Electron microscopy ; Immunocytochemistry
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The question of whether the development of CNS glial cells requires the presence of axons or not can be studied with in vitro systems. In order to compare the differentiation of glial cells during development in vitro with that in situ, we have selected the optic nerve, which is anatomically as well as histotypically a well defined structure. For the in vitro investigations, small explants, called minisegments, of newborn rat optic nerves were cultivated taking four major conditions into account: (1) the regular size of the minisegments should guarantee a permanent exchange of the culture medium in order to avoid cell death, (2) neither mechanical nor enzymatic dissociation of the tissue were applied, (3) the minisegments were explanted into flasks without substrate for cell adhesion and (4) the minisegments were under constant gyratory agitation. The following in situ results were obtained: optic nerves of newborn rats are morphologically characterized by the presence of naked axons, astrocytes, glial precursors, and the absence of both differentiated oligodendrocytes and myelin. At postnatal day 5 myelin sheaths are still absent. Two weeks after birth, differentiated oligodendrocytes and microglial cells are present and numerous axons are surrounded by compact myelin. The in vitro experiments show the following main results, which were obtained after 14 h, 2 d, 5 d and 14 d in culture: during time in culture, the shape of minisegment of newborn rat optic nerves undergoes drastic changes, which indicate high cellular dynamics. After 14 h in vitro, axonal profiles, cells with pyknotic nuclei as well as clusters of astrocytes and glial precursors are present. After 2 days in culture the axonal profiles disappeared and the number of degenerating cells decreased drastically. Many large cells, probably phagocytes containing inclusions and more cells are differentiated. At the stage of 5 d in vitro 4 major types of cells can be distinguished: differentiated oligodendrocytes, which form compact and loose myelin, astrocytes, large and small glioblasts and phagocytes. Immunoprecipitates for myelin basic protein and/or myelin associated glycoprotein were found in oligodendrocytes, in their processes and associated to the myelin. Processes of some astrocytes showed immunoreactive products of glial fibrillary acidic protein. After two weeks in culture, the minisegments were mostly composed of astrocytes, whereas oligodendrocytes became rare and phagocytes disappeared. It can be concluded that CNS glial cells can attain their structural and immunocytochemical characteristics in the total absence of neuronal cell bodies and axons. However, it can be speculated that neurons (or neuronal factors) could regulate the number of astrocytes and oligodendrocytes and keep these glial cells in a physiological equilibrium.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00243842
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  • 75
    Digitale Medien
    Digitale Medien
    A paediatric case of sideroblastic anaemia (1986)
    Springer
    European journal of pediatrics 145 (1986), S. 422-427 
    Details
    ISSN: 1432-1076
    Schlagwort(e): CFU-E ; BFU-E ; Electron microscopy ; Sideroblastic anaemia ; Dyserythropoiesis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract We examined the morphological and functional characteristics of erythroblasts derived from marrow erythroid progenitor cells grown in a methylcellulose microculture, which were taken from a female child with rate atypical sideroblastic anaemia (SA) partially responsive to pyridoxine. Colony formation was within the normal range in three successive cultures (median values: 82.25 CFU-E and 16.4 BFU-E derived colonies/6.6×104 cells) compared to growth by normal cells (65-315 CFU-E and 9-40 BFU-E). We evaluated in vitro differentiation by biochemical microassay of a cytosol enzyme involved in the haeme pathway: uroporphyrinogen I synthase (UROS). The UROS values in the erythroid colonies from SA marrow were at the lower end of the normal range (median values: 6.7±0.3 and 14.4±3.8 pmol uroporphyrinogen/h in CFU-E and BFU-E-derived colonies respectively versus 17.4±7.3 and 25±7.2 pmol/h in CFU-E and BFU-E colonies from normal subjects. Ultrastructural examination of the SA erythroblasts from non-cultured bone marrow or derived from cultured BFU-E revealed the characteristic deposition of iron in mitochondria around the nucleus of most cells (ringed sideroblasts). However, the majority of cultured cells had marked dyserythropoietic featuress, with a large number of bilobulated or trilobulated crythroblasts, multiple cytoplasmic vacuoles, numerous abnormalities of the nucleus, and excessive membrane material beneath the plasma membrane, all features difficult to observe in non-cultured marrows.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00439253
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  • 76
    Digitale Medien
    Digitale Medien
    Cytomorphological changes in liver cells exposed to allyl and benzyl isothiocyanate and their cysteine and glutathione conjugates (1986)
    Springer
    Archives of toxicology 59 (1986), S. 103-110 
    Details
    ISSN: 1432-0738
    Schlagwort(e): Cytotoxicity ; Cell morphology ; RL-4 hepatocyte ; Electron microscopy ; In vitro study ; Allyl isothiocyanate ; Benzyl isothiocyanate ; Tert-butylhydroperoxide
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Since allyl isothiocyanate has been reported to be a bladder carcinogen and benzyl isothiocyanate is a known anti-carcinogen, it is important to know the mode of their cytotoxic action. This was investigated in a RL-4 hepatocyte cell line by studying the morphological effects of increasing concentrations of the isothiocyanates and their glutathione and cysteine conjugates. These effects were compared with those induced by tert-butylhydroperoxide which supposedly has its primary effect upon the cytosolic glutathione status and thus upon the integrity of Ca2+-sequestrating mitochondria. The results agree with the previously postulated role of conjugation in the exposure of cells to isothiocyanates: Conjugates show effects similar to those produced by the free parent compounds because conjugates release free isothiocyanates in aqueous solution. The cytomorphological effects increase in a more or less dose-dependent manner with increasing concentrations of isothiocyanate or exposure time. Probably due to increased exposure, suspended RL-4 cells are more sensitive to the toxic action than cells growing on a substrate. No qualitative differences were found between the effects of allyl and benzyl isothiocyanate, indicating that their different effects in vivo are perhaps related to organ-specific differences in equilibrium between the conjugated and unconjugated forms of the test substances. The first cytomorphological effects of isothiocyanates consist of surface blebbing (zeiosis) and swelling of dictyosomal cisternae. At higher concentrations swelling extends to vesicles of endoplasmic reticulum. Mitochondria are not affected until the cells reach the necrotic phase of injury. In contrast, tert-butylhydroperoxide causes mitochondrial damage in an early pase of toxic injury. The cellular symptoms suggest that the primary target of isothiocyanates is in the plasma membrane and the cellular membrane system, affecting the monovalent cation and water balance of the cell organelles rather than the Ca2+ homeostasis as in cells exposed to tert-butylhydroperoxide. Differences in lipophilicity may be at the basis of this differenc in primary action.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00286732
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  • 77
    Digitale Medien
    Digitale Medien
    An electron microscopic study of cerebral vasospasm with resultant myonecrosis in cases of subarachnoid haemorrhage, meningitis and trans-sylvian surgery (1986)
    Springer
    Journal of neurology 233 (1986), S. 348-357 
    Details
    ISSN: 1432-1459
    Schlagwort(e): Cerebral vasospasm ; Myonecrosis ; Myofilament ; Calcium ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Electron microscopic data on the development of myonecrosis following cerebral vasospasm associated with subarachnoid haemorrhage, meningitis and trans-sylvian surgery are presented. The basic feature of myonecrosis was dissolution of myofilaments with resultant fine granular or filamentous material. The disintegrating cytoplasm often contained numerous glycogen granules, dense bodies, autophagic vacuoles and myelin-like membranous bodies. A well-developed sarcoplasmic reticulum was preserved despite myofilament dissolution, while mitochondria showed marked sweling. The nuclei showed either dilution of chromatin or pyknotic change. The basal lamina was remarkably thickened and maintained an irregular outline of the necrotic smooth muscle cells. Enlarged intercellular space contained abundant cellular debris, vesicular structures and connective tissue fibres. The pathogenesis of these changes is discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00313921
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  • 78
    Digitale Medien
    Digitale Medien
    A three dimensional model of the photosynthetic membranes of Ectothiorhodospira halochloris (1986)
    Springer
    Archives of microbiology 146 (1986), S. 267-274 
    Details
    ISSN: 1432-072X
    Schlagwort(e): Photosynthesis ; Membrane structure ; Electron microscopy ; Ectothiorhodospira ; Serial thin sectioning ; Three dimensional reconstruction
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The three dimensional organization of the complete photosynthetic apparatus of the extremely halophilic, bacteriochlorophyll b containing Ectothiorhodospira halochloris has been elaborated by several techniques of electron microscopy. Essentially all thylakoidal sacs are disc shaped and connected to the cytoplasmic membrane by small membraneous “bridges”. In sum, the lumina of all thylakoids (intrathylakoidal space) form one common periplasmic space. Thin sections confirm a paracrystalline arrangement of the photosynthetic complexes in situ. The ontogenic development of the photosynthetic apparatus is discussed based on a structural model derived from serial thin sections.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00403228
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  • 79
    Digitale Medien
    Digitale Medien
    Role of relA mutation in the survival of amino acid-starved Escherichia coli (1986)
    Springer
    Archives of microbiology 143 (1986), S. 400-402 
    Details
    ISSN: 1432-072X
    Schlagwort(e): E. coli relA +/relA ; Starvation survival ; Guanosine tetraphosphate ; Electron microscopy ; Glycogen
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Amino acid-starved cells of Escherichia coli relA +, which contain a large number of glycogen particles, are able to survive in phosphate buffer for a longer time period than their relaxed counterparts. With regard to NH 4 + starvation differences in the survival of both strains were not found. NH 4 + starved cells of E. coli relA are able to synthesize glycogen but amino acid-starved cells of the relA strain are not. We suggest that the synthesis of glycogen triggered by guanosine tetraphosphate during amino acid starvation is responsible for the prolonged viability of the E. coli relA + strain.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00412809
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  • 80
    Digitale Medien
    Digitale Medien
    Bradyrhizobium japonicum mutants defective in root-nodule bacteroid development and nitrogen fixation (1986)
    Springer
    Archives of microbiology 144 (1986), S. 355-366 
    Details
    ISSN: 1432-072X
    Schlagwort(e): Bradyrhizobium ; Electron microscopy ; Mutants ; Nitrogen fixation ; Nodulation ; Soybean ; Symbiosis ; Transposon Tn5
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The genome of the slow-growing Bradyrhizobium japonicum (strain 110) was mutagenized with transposon Tn5. A total of 1623 kanamycin/streptomycin resistant derivatives were screened in soybean infection tests for nodulation (Nod) and symbiotic nitrogen fixation (Fix). In this report we describe 14 strains possessing a stable, reproducible Nod+Fix- phenotype. These strains were also grown under microaerobic culture conditions to test them for free-living nitrogen fixation activity (Nif). In addition to strains having reduced Fix and Nif activities, there were also strains that had reduced symbiotic Fix activity but were Nif+ ex planta. Analysis of the genomic structure revealed that the majority of the strains had a single Tn5 insertion without any further apparent physical alteration. A few strains had additional insertions (by Tn5 or IS50), or a deletion, or had cointegrated part of the vector used for Tn5 mutagenesis. One of the insertions was found in a known nif gene (nifD) whereas all other mutations seem to affect different, hitherto unknown genes or operons. Several mutant strains had an altered nodulation phenotype, inducing numerous, small, widely distributed nodules. Light and electron microscopy revealed that most of these mutants were defective in different stages of bacteroid development and/or bacteroid persistence. The protein patterns of the mutants were inspected by two-dimensional gel electrophoresis after labelling microaerobic cultures with l-(35S)methionine. Of particular interest were mutants lacking a group of proteins the synthesis of which was known to be under oxygen control. Such strains can be regarded as potential regulatory mutants.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00409885
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  • 81
    Digitale Medien
    Digitale Medien
    Pathogenesis of pulmonary fibrosis induced by chrysotile asbestos (1986)
    Springer
    Virchows Archiv 408 (1986), S. 329-346 
    Details
    ISSN: 1432-2307
    Schlagwort(e): Pulmonary fibrosis ; Asbestosis ; Chrysotile ; Macrophages ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary A single instillation of 1 mg chrysotile B with a fiber length between 0.05 and 0.2 µm in 0.1 ml tricaprylin was made via a polyvinyl catheter into the lower lobe of the right lung of 120 six-week-old Wistar rats under anesthesia. The animals were killed at intervals between five minutes and two years. The lower lobes of the right lung were investigated by light and electron microscopy. The process of pulmonary fibrosis induced by asbestos can be subdivided into four phases: these are the phase of phagocytosis (five to 15 min), the phase of granuloma formation (between one and two weeks), the phase of septal fibrosis (between two and six months) and finally the scar stage (after one year). After instillation of small asbestos fibers into the alveoli, a major proportion of these fibers is phagocytosed by alveolar macrophages after five minutes and leaves the lungs via the airways. A proportion of the fibers penetrates through the alveolar wall (mostly conveyed by type I pneumocytes) and reaches the interstitium of the lungs. There, the fibers are taken up by pulmonary tissue macrophages and giant cells. Within the phagolysosomes, the fibers are broken down into fragments less than 0.01 µm in length. Type II pneumocytes produce surfactant in excess. These cells become necrotic, tubular myelin and lamellar bodies pass into the alveoli and into the interstitium. Surfactant is phagocytosed by resident macrophages. These macrophages phages can break down. Besides asbestos and surfactant, mediators of fibrillogenesis are released. Macrophages following up from blood monocytes ingest surfactant and asbestos. This process is perpetuated up to complete scarring. After two years, small asbestos fibers less than 0.01 µm long are present in fibroblasts and pleural mesothelia.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00707692
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  • 82
    Digitale Medien
    Digitale Medien
    Diversity of Vicia faba circular mtDNA in whole plants and suspension cultures (1986)
    Springer
    Theoretical and applied genetics 72 (1986), S. 541-547 
    Details
    ISSN: 1432-2242
    Schlagwort(e): Mitochondrial DNA of plants ; Electron microscopy ; Suspension culture ; Vicia faba
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary A comparative analysis of the Vicia faba mitochondrial genome in whole plants and in longterm suspension culture has been conducted. Restriction fragment patterns of the mtDNA isolated from these two sources were notably different. Electronmicroscopic analysis also revealed significant differences. Large circular mtDNA patterns shifted from a 37–80 kb subpopulation, which was predominant in whole plants, to 18–34 kb subpopulations although in both classes notable quantities of circular molecules of 80 to 120 kb and more were also found. Both in whole plant and suspension culture cells very large circular DNAs were observed. Some of them had lengths nearly 290 kb and could be considered as evidence of the existence of master chromosomes. The minicircular DNA population was also altered. In the suspension culture we observed a notable increase of percentage of minicircles with sizes near 1 kb. Simultaneously, the percentage of minicircles with sizes near 3.5–10 kb significantly increased in suspension culture cells. In addition, a new peak (10–12 kb) of minicircles appeared. Copy number alterations for some sequences homologous to CCC1A, CCC1B and CCC2 (Negruk et al. 1982, 1985) were shown. Southern hybridization revealed the existence of a family of minicircles having sizes 1.4–2 kb with predominance of CCC1A, CCC1B and CCC2. The copy numbers of CCC1B and some minor minicircles was changed in the suspension culture when compared with the whole plants.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00289538
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  • 83
    Digitale Medien
    Digitale Medien
    Lipokeratinocytes of the epidermis of a cetacean (Phocena phocena) (1986)
    Springer
    Cell & tissue research 244 (1986), S. 385-394 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Cetaceans ; Lamellar bodies ; Epidermal lipids ; Permeability barrier ; Electron microscopy ; Phocena phocena
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Biochemical and ultrastructural analysis of epidermis from the porpoise, Phocena phocena, revealed certain similarities and differences between cetaceans and terrestrial mammals. The predominant cell of cetacean epidermis, not found in normal terrestrial mammals, is a lipoker-atinocyte, which elaborates not only keratin filaments, but also two types of lipid organelles: first, lamellar bodies, morphologically identical to those of terrestrial mammals, are elaborated in great abundance in all suprabasal epidermal layers, forming intercellular lipid bilayers in the stratum corneum interstices: and second, non-membrane-bounded droplets appear and persist in all epidermal layers. Although the porpoise lipokeratinocyte morpologically resembles the sebokeratocyte of avians in certain respects, nonmembrane-bounded lipid droplets are not released into the intercorneocyte space as they are in avian stratum corneum. Whereas phospholipid/neutral lipid gradients are similar in porpoise and terrestrial mammals, PAS-positive glycoconjugates, specifically glycosphingolipids, are retained in porpoise stratum corneum, but lost from these layers in terrestrials. The novel, non-polar acylglucosyl-ceramides, which also are lost during cornification in terrestrial mammals, are retained in porpoise stratum corneum. The lipid components of porpoise lipokeratinocytes appear to subserve not only barrier function in a hypertonic milieu, but also underlie the unique buoyancy, streamlining, insulatory, and caloric properties exhibited as adaptations to the cetacean habitat.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00219214
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  • 84
    Digitale Medien
    Digitale Medien
    Collagen remodeling during decidualization in the mouse (1986)
    Springer
    Cell & tissue research 244 (1986), S. 443-448 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Collagen ; Uterus ; Decidua ; Mouse ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary An ultrastructural study of the features and distribution of collagen fibrils was performed in the endometrium of virgin and pregnant (2nd to 11th day) mice. Collagen-containing structures were observed in the cytoplasm of fibroblasts on the 2nd day of pregnancy. Treatment of tissues with lanthanum nitrate established that these structures were intracytoplasmic. Their association with lysosome-like bodies suggested the occurrence of intracellular digestion of collagen, probably connected with remodeling of the endometrial stroma prior to decidualization. On the 4th day of pregnancy, very few collagen fibrils were present in the intercellular space. From the 6th day of pregnancy onwards, “thick” collagen fibrils were observed between decidual cells. The diameter of these fibrils measured up to 300 nm whereas the fibrils present in the endometrium of virgin mice measured 40–68 nm.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00219220
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  • 85
    Digitale Medien
    Digitale Medien
    Culture of intramural cardiac ganglia of the newborn guinea-pig (1986)
    Springer
    Cell & tissue research 244 (1986), S. 605-612 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Heart innervation ; Tissue culture ; Autonomic ganglia ; Non-neuronal cells ; Cell interrelationships ; Electron microscopy ; Guinea-pig
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The present study describes the ultrastructure of non-neuronal cells and their interrelationships with intracardiac neurones present in cultures dissociated atria and interatrial septum from newborn guinea-pig. When compared with the in situ preparation, most of these features in culture were similar to those observed in situ, but some differences were also apparent. Both mature and immature Schwann cells were observed in culture, and as in situ, the latter were closely associated with intracardiac neurones, whilst the former were more widely separated. The ultrastructure of satellite cells was more variable in culture than in situ: three general types were distinguished on the basis of their 10-nm filament content. This variation could be due to conditions of culture. Interstitial cells were present in culture and closely resembled those described in situ, although there was less space between cultured interstitial cells and their associated cells. Many fibroblasts, some myoblasts and a few mast cells were also found in the culture preparations.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00212540
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  • 86
    Digitale Medien
    Digitale Medien
    Culture of intramural cardiac ganglia of the newborn guinea-pig (1986)
    Springer
    Cell & tissue research 244 (1986), S. 595-604 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Heart innervation ; Tissue culture ; Autonomic ganglia ; Neurones ; Small granule-containing cells ; Electron microscopy ; Guinea-pig
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The ultrastructure of cultured intrinsic neurones and SIF (small intensely fluorescent) cells dissociated from the atria and interatrial septum of newborn guinea-pig heart has been studied for the first time and compared with these cells in situ. Mononucleate and binucleate neuronal somata and their processes were observed in the culture preparation; their ultrastructure was similar to that of neurones in intracardiac ganglia observed in situ. The number of neurites associated with neuronal cell bodies increased after the first week in culture. A subpopulation of intracardiac neurones showed abnormalities in culture, comparable to the changes previously described in neurones of the monkey heart after unilateral vagotomy in situ. Small granule-containing cells were observed in culture, corresponding to those described in the heart in situ. One type of large process in the culture preparation containing densely packed mitochondria has not been seen in situ, suggesting that changes in cell ultrastructure due to the conditions of culture cannot be discounted. However, the ultrastructure of the cultured cells was, for the most part, consistent with that of the same cell type in situ, indicating that the culture preparation may be a useful model for investigation of the roles and interactions of intramural neurones in the heart, which are inaccessible for such studies in situ.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00212539
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  • 87
    Digitale Medien
    Digitale Medien
    Morphological evidence for the existence of a more complex cytoskeleton in Amoeba proteus (1986)
    Springer
    Cell & tissue research 246 (1986), S. 163-168 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Cytoskeletal organization ; Filaments ; Triton extraction ; Replica technique ; Electron microscopy ; Amoeba proteus
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Various stabilization and extraction procedures were tested to demonstrate the ultrastructural organization of the cytoskeleton in normal, locomoting Amoeba proteus. Most reliable results were obtained after careful fixation in glutaraldehyde/lysine followed by prolonged extraction in a polyethylene glycol/Triton X-100 solution. Before dehydration in a graded series of ethanol and critical-point drying, the amoebae were split by the sandwich-technique, i.e., by mechanical cleavage of cells mounted between two poly-L-lysine-coated glass slides. Platinum-carbon replicas as well as thin sections prepared from such cell fragments revealed a cytoskeleton composed of at least four different types of filaments: (1) 5–7-nm filaments organized as a more or less ordered cortical network at the internal face of the plasma membrane and probably representing F-actin; (2) 10–12-nm filaments running separately or slightly aggregated through the cytoplasm and probably representing intermediate filaments; (3) 24–26-nm filaments forming a loose network and probably representing microtubules; and (4) 2–4-nm filaments as connecting elements between the other cytoskeleton constituents. Whereas microfilaments are responsible for protoplasmic streaming and other motile phenomena, the function of intermediate filaments and cytoplasmic microtubules in amoebae is still obscure.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00219013
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  • 88
    Digitale Medien
    Digitale Medien
    Structure and development of the surface coat of erythrocytic merozoites of Plasmodium knowlesi (1986)
    Springer
    Cell & tissue research 245 (1986), S. 281-290 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Electron microscopy ; Malaria parasites ; Merozoites ; Surface coat ; Maturation ; Plasmodium knowlesi
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The surface of extracellular merozoites of P. knowlesi is covered with a coat 15–20 nm thick, made up of clusters of filaments standing erect on the plasma membrane. Filaments have stems 2 nm thick, the peripheral ends of which are complex, branching or ending in long trailing threads. Coat filaments occur on the surface of the parasite in regular rows at an early schizont stage, and persist until well after merozoite release. They are sensitive to trypsin and papain, and bind ethanolic phosphotungstate, indicating a proteinaceous nature. They are also removed by exposure to phosphate-buffered saline. Filaments bear negative charges, binding cationised ferritin throughout the depth of the coat and staining with ruthenium red. They cover the whole merozoite surface and mediate intercellular adhesion at distances of 15–150 nm, membrane to membrane. It is suggested that these filaments correspond to a major merozoite surface protein, and are important in the initial capture of red cells.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00213933
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  • 89
    Digitale Medien
    Digitale Medien
    Nephridial innervation in the leech Hirudo medicinalis L. (1986)
    Springer
    Cell & tissue research 245 (1986), S. 397-404 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Leech ; Nephridium ; Innervation ; Electron microscopy ; Cobalt filling ; Hirudo medicinalis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The main organs for salt and water homeostasis in the medicinal leech, the nephridia, were found to be densely innervated by a single branch of the corresponding median anterior segmental nerve. The projections of two different neurons into the nephridia are described: 1. Dendritic projections of the previously identified, afferent ‘nephridial nerve cell’, a possible salt receptor, lie between the urine forming cells and the blood vessels supplying the nephridium without making any contact. 2. Projections of an unidentified neuron which contains dense-core vesicles (85 nm) as well as smaller clear vesicles (45 nm) contact the primary urine forming canaliculus cells. The neurosecretory role of these neurons is considered.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00213947
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  • 90
    Digitale Medien
    Digitale Medien
    The coxo-trochanteral muscle receptor organ of locusts (1986)
    Springer
    Cell & tissue research 243 (1986), S. 517-524 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Muscle receptor organ ; Electron microscopy ; Tubular body ; Mechanosensory transduction ; Locust, Locusta migratoria migratorioides (R.&F.)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The coxo-trochanteral muscle receptor organ of the hind leg of the locust Locusta migratoria migratorioides (R.&F.) has been investigated by use of scanning and transmission electron microscopy with special emphasis on its distal attachment site. The overall morphology of the receptor muscle, the sensory neuron and its dendrites was found to share many common features with other arthropod sense organs of that type with two important differences: (1) the connective tissue segment (= intercalated tendon) is extremely short compared to that of other muscle receptor organs; (2) the naked dendritic terminals of the non-ciliated, multipolar sensory neuron of the organ contain clusters of microtubules, interconnected by an amorphous matrix, that resemble the tubular bodies of ciliated, epithelial receptor cells.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00218058
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  • 91
    Digitale Medien
    Digitale Medien
    The hypothalamo-hypophysial system of the frog Rana temporaria (1986)
    Springer
    Cell & tissue research 243 (1986), S. 649-654 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Median eminence ; Peptidergic projections ; Aminergic projections ; Electron microscopy ; Autoradiography ; Frog (Rana temporaria)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The median eminence (ME) of the adult frog, Rana temporaria, was studied by means of electron microscopy including quantitative electron-microscopic autoradiography. In frogs captured in May and June numerous peptidergic neurosecretory fibres extending via the internal zone to the pars nervosa display large swellings containing few granules, mitochondria, neurotubules and cisternae of the smooth endoplasmic reticulum. In addition, few secretory globules up to 1.5 μm in diameter occur in these varicosities. In animals collected during the autumn period many of these neurosecretory swellings filled with neurosecretory granules and polymorphic inclusions resemble Herring bodies. Three types of granule-containing neurosecretory fibres were observed in the external zone (EZ) of the ME of adult R. temporaria. Peptidergic A1- and A2-type fibres are characterized by granules 150–220 nm and 100–160 nm in diameter, respectively. Monoaminergic fibres of type B with granules approximately 100 nm in diameter represent ∼ 50% of all neurosecretory elements in the EZ of the frog ME; ∼12% of the total number of granule-bearing axons in the EZ actively taking up radiolabelled 5-hydroxytryptophan are thought to be serotoninergic terminals. Neurosecretory terminals of all types and glial vascular endfeet establish direct contacts with the perivascular space of the primary portal capillaries. Some neurosecretory terminals are separated from the lumen of the third ventricle by a thin cytoplasmic lamella of tanycytes. The possible physiological significance of this structural pattern is discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00218074
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  • 92
    Digitale Medien
    Digitale Medien
    An ultrastructural study of embryonic chick retinal neurons in culture (1986)
    Springer
    Cell & tissue research 245 (1986), S. 563-577 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Chick retina ; Tissue culture ; Electron microscopy ; Development, ontogenetic ; Differentiation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The differentiation of cells and synapses in explants of 9-day-old chick embryo retina has been studied by light and electron microscopy over a period of 35 days in vitro, and samples of retina from the 9-day chick foetus were directly fixed and prepared for study. At the time of explantation the retinae were poorly differentiated and no lamination was apparent. From day 14 onwards, (i) outer and inner nuclear layers (ONL, INL) separated by a layer of neuropil corresponding to the outer plexiform layer (OPL) and (ii) a layer of scattered large ganglion cells separated from the INL by a zone of neuropil resembling the inner plexiform layer (IPL) were apparent, and (iii) a well-differentiated outer limiting membrane was established close to the surface of the explants. In the oldest cultures some development of photoreceptor outer segments occurred but a distinct optic nerve fibre layer did not form. Although cell identification presented problems even in the oldest cultures, the major retinal cell types described in vivo could be identified. Photoreceptor cells developed pedicles in the OPL which became filled with synaptic vesicles and synaptic ribbons and established ribbon synapses (including triads) with and were commonly invaginated by processes from horizontal and bipolar cells. Processes of bipolar cells in the IPL formed simple and dyad synapses. At least two types of presynaptic amacrine cells were also identified in the INL, one of which contained large numbers of dense-core vesicles. The ganglion cells, though sparse, were large and well differentiated. These findings show that all the major neuronal types of the retina are capable of developing and differentiating in vitro, lagging behind the time-table of development and differentiation in vivo by approximately 7 days, but resulting in a histotypically organised retina with synaptic neuropil showing many similarities to the corresponding neuropil in vivo.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00218558
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  • 93
    Digitale Medien
    Digitale Medien
    Embryonic cholinesterase activity during morphogenesis of the mouse genital tract (1986)
    Springer
    Cell & tissue research 244 (1986), S. 153-164 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Cholinesterase ; Genital tract ; Mesenchyme ; Histochemistry ; Electron microscopy ; Mouse embryo
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary In the genital tract of male and female mouse embryos cholinesterase activity is described that is independent from innervation. The enzyme activity is localized in the mesenchyme at the junction of Wolffian and Müllerian ducts with the urogenital sinus. During male development prostate buds and vesicular glands grow out into the cholinesterase-active mesenchyme. During female development the active mesenchyme participates in the downgrowth of the vaginal anlage. Ultrastructurally the cholinesterase activity is localized in the perinuclear cisterna and in smooth endoplasmic reticulum of the mesenchymal cells. The enzyme activity disappears with definitive differentiation of the tissue. The embryonic cholinesterase is a component of a primitive muscarinic system. Its relation to the morphogenetic action of testosterone and its possible general functions are discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00218393
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  • 94
    Digitale Medien
    Digitale Medien
    Cytoplasmic virus-like particles associated with the nucleolus in wheat, similar to “S bodies” and retroposon particles (1986)
    Springer
    Protoplasma 133 (1986), S. 160-164 
    Details
    ISSN: 1615-6102
    Schlagwort(e): Cytoplasm ; Electron microscopy ; Nucleolus ; Virus-like particles ; Wheat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Wheat roots from germinating seedlings of Chinese spring wheatTriticum aestivum grown for 36 hours at 20°C were examined by conventional thin-section electron microscopy. Virus-like particles were seen inside a large cytoplasmic intrusion into the nucleus having the appearence of a nucleolar vacuole. The particles were isometric and about 50 nm in diameter with a membrane-like coat and a small core. The cytoplasmic intrusion was bounded by nuclear envelope with pores apparent where it abutted nucleoplasm. The particles are similar to previously reported solitary particles “S bodies” from a range of plants but are also similar in size and morphology to the retroposon particles associated with copia like elements in other organisms. The position of the virus-like particles in the young wheat roots is discussed in relation to interactions with components of the cell skeleton.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01304631
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  • 95
    Digitale Medien
    Digitale Medien
    Influence of culture medium pH on charasome development and chloride transport inChara corallina (1986)
    Springer
    Protoplasma 130 (1986), S. 5-11 
    Details
    ISSN: 1615-6102
    Schlagwort(e): Chara corallina ; Charasome development ; Chloride transport ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Internodal cells ofChara, grown in culture either at pH 5.7, 6.5 or 7.5, were studied to determine their chloride influx capability, the quantitative aspects of charasome morphology and the degree to which these two parameters could be correlated. In cells grown at pH 5.7 the charasomes were relatively small, were widely spaced on the plasma membrane, and contributed only a 0.6% increase to the surface area of the plasma membrane in the acid region of the cell. In contrast, the charasome membrane surface area of cells grown at pH 7.5 had increased × 19, the density of charasomes on the cell surface increased × 42, thus producing a × 3.57 increase in the acid region plasma membrane surface area. Chloride influx in cells grown at pH 7.5 was × 8.7–12.7 greater than in cells grown at pH 5.7. Cells that had been starved of chloride exhibited a × 2.4 average increase in the rate of chloride influx. Our observations establish the existence of a positive correlation between the rate of chloride influx and the increase in membrane surface area due to charasomes, although other factors, such as the effect of pH on transport-related enzymes, and the effect of charasome structure on chemical equilibria, may also be of importance.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01283326
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  • 96
    Digitale Medien
    Digitale Medien
    The effects of raised phosphate level on the energy metabolism, contractile function, and fine structure of oxygenated and oxygen-deficient myocardium (1986)
    Springer
    Heart and vessels 2 (1986), S. 6-14 
    Details
    ISSN: 1615-2573
    Schlagwort(e): Inorganic phosphate ; Normoxia/anoxia ; ATP ; Glycogen ; Cardiac function ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The possible role of inorganic phosphate (Pi) in depressing the contractility of oxygen-deficient myocardium was investigated by examining the effects of 30 mM Pi on the cardiac function and myocardial biochemistry and fine structure in normoxic and anoxic Langendorff-perfused isolated rat hearts. In normoxia, the intracellular Pi level increased three-fold, the ATP content remained normal, and there was moderate loss of glycogen only. Contractile performance (as assessed from systolic pressure recordings) was significantly depressed, as was the heart rate for the first 10 min. The myocardial fine structure showed persistent glycogen, marked relaxation of myofibrils, and a higher incidence of vacuolation than in hearts with normal Pi. In anoxia, the intracellular Pi level was comparable with that of the perfusate and both ATP and glycogen were severely depleted. Contractile performance and heart beat ceased completely at 15 min, although in anoxic controls both persisted at low levels for at least 25 min. In anoxia, Pi also depressed coronary flow rate. In the inner half of the ventricular wall of oxygen-depleted hearts, where flow became reduced after 15 or more min, Pi markedly reduced the formation of intramitochondrial densities and augmented mitochondrial swelling and ischaemic contracture, which extended out through the mid-myocardium. In the outer half of the wall, where flow remained high, it promoted severe dilatation of the sarcoplasmic reticulum vesicles and undifferentiated regions of the intercalated discs. The observed effects in normoxia are probably attributable at least in part to the lowering of the free Ca2+ concentration of the perfusate by the increased Pi level. The effects in anoxia may be related chiefly to the critical reduction of available intracellular Ca2+ and the more rapid and extensive development of ischaemic contracture.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02060238
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  • 97
    Digitale Medien
    Digitale Medien
    In vivo homologous recombination intermediates of yeast mitochondrial DNA analyzed by electron microscopy (1986)
    Springer
    Molecular genetics and genomics 202 (1986), S. 421-428 
    Details
    ISSN: 1617-4623
    Schlagwort(e): Recombination intermediates ; Mitochondrial DNA ; Electron microscopy ; Saccharomyces cerevisiae
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary To study the structure of in vivo mitochondrial DNA recombination intermediates in Saccharomyces cerevisiae, we used a deletion mutant of the wild type mitochondrial genome. The mtDNA of this petite is composed of a direct tandem repetition of an ∼4,600 pb monomer repeat unit with a unique HhaI restriction enzyme site per repeat. The structure of native mtDNA isolated from log phase cells, and mtDNA crosslinked in vivo with trioxsalen plus UVA irradiation, was studied by electron microscopy. Both populations contained crossed strand “Holliday” type recombination intermediates. Digestion of both non-crosslinked and crosslinked and mtDNA with the enzyme HhaI released X and H shaped structures composed of two monomers. Electron microscopic analysis revealed that these structures had pairs of equal length arms as required for homologous recombination intermediates and that junctions could occur at points along the entire monomer length. The percentage of recombining monomers in both non-crosslinked and trioxsalen crosslinked mtDNA was calculated by quantitative analysis of all the structures present in an HhaI digest. The relationship between these values and the apparent dispersive replication of mtDNA in density-shift experiments and mtDNA fragility during isolation is discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00333272
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  • 98
    Digitale Medien
    Digitale Medien
    Electron microscopic localization of hydrogenase genes on the megaplasmid pHG 1 in Alcaligenes eutrophus (1986)
    Springer
    Molecular genetics and genomics 202 (1986), S. 476-480 
    Details
    ISSN: 1617-4623
    Schlagwort(e): Hydrogen bacterium ; Hydrogenase genes ; Megaplasmid pHG1 ; Localization ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Plasmids carrying hydrogenase genes in Alcaligenes eutrophus wild type H 16 and in two transposon Tn5 —induced mutants have been investigated by electron microscopy. Besides the pHG1 megaplasmid (458±27 kb) carrying genes coding for structural and regulatory properties of hydrogenases, small plasmids of unknown significance have been detected. The sizes of EcoRI fragments obtained from pHG1 were measured from electron micrographs. They were significantly different from sizes determined previously by agarose gel electrophoresis. Plasmid pHG1 isolated from the wild type H 16 was shown to contain two inverted repeats (IR 16-1 and IR 16-2) with sizes similar to known transposons. From electron microscopic hybridization studies, it was deduced that the sites of insertion of Tn5 into a regulation gene on pHG1 for both soluble and membrane-bound hydrogenase, and of Tn5-Mob into the gene coding for structural properties of the soluble hydrogenase, are about 67.2 kb apart. One of the inverted repeats (IR 16-1) was localized in between these sites.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00333280
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  • 99
    Digitale Medien
    Digitale Medien
    Abnormal mucociliary function in a mucocoele of the maxillary antrum (1986)
    Springer
    European archives of oto-rhino-laryngology and head & neck 243 (1986), S. 207-210 
    Details
    ISSN: 1434-4726
    Schlagwort(e): Maxillary sinus mucocoele ; Mucociliary system ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary We have examined the mucociliary function present in a mucocoele of the maxillary antrum and have found certain abnormalities in the tissues studied. Our findings also indicate that the mucocoele's intrinsic pathology is too complex to be improved by any conservative treatment and justifies its surgical removal.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00470623
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  • 100
    Digitale Medien
    Digitale Medien
    An experimental study of auditory dysfunction associated with hyperlipoproteinemia (1986)
    Springer
    European archives of oto-rhino-laryngology and head & neck 243 (1986), S. 242-245 
    Details
    ISSN: 1434-4726
    Schlagwort(e): Hyperlipoproteinemia ; Auditory dysfunction ; Cochlea ; Histochemistry ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary We sought to clarify whether or not hyperlipoproteinemia induces auditory dysfunction. In so doing, we studied the general states and cochlear pathologies of guinea pigs after the administration of a hyperlipid diet for 3 months. Serum biochemistries indicated marked elevations of cholesterol, high density lipoprotein (HDL)-cholesterol and low density lipoprotein (LDL) levels. An increased auditory threshold varying from 10 to 20 dB was observed in 40% of the guinea pigs using auditory brainstem responses. Histochemical study of the inner ear revealed variations in lipid metabolism and partial disorders of the outer hair cells. Electron microscopic observations showed vacuolar and parenchymal protrusions on the surfaces of the stria vascularis and Corti's organ, and vacuolar degeneration was seen around the capillary vessels of the vascular stria. Our data has shown that the auditory dysfunction present in the inner ear was less marked than were the morphological changes seen. Our findings suggest that other factors besides hyperlipoproteinemia are involved in the development of severe auditory damage.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00464438
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