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  • 2000-2004
  • 1990-1994  (59)
  • 1975-1979  (620)
  • 1890-1899
  • 1991  (59)
  • 1976  (620)
  • Physics  (492)
  • Electron microscopy
  • 1
    Electronic Resource
    Electronic Resource
    Histomorphological aspects of vascular anastomosis established by laser (1991)
    Springer
    Lasers in medical science 6 (1991), S. 363-366 
    Details
    ISSN: 1435-604X
    Keywords: Laser vascular welding ; Tissue fusion ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02030894
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  • 2
    Electronic Resource
    Electronic Resource
    Organ-specific crystalline structures of ferritin cores inβ-thalassemia/hemoglobin E (1991)
    Springer
    BioMetals 4 (1991), S. 162-165 
    Details
    ISSN: 1572-8773
    Keywords: Ferritin ; Thalassemia ; Ferrihydrite ; Crystallinity ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01141308
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  • 3
    Electronic Resource
    Electronic Resource
    Claws of cilia: Further observation of ciliated epithelium in neurenteric cyst (1991)
    Springer
    Virchows Archiv 418 (1991), S. 263-265 
    Details
    ISSN: 1432-2307
    Keywords: Neurenteric cyst ; Enterogenous cyst ; Cilia ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01606065
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  • 4
    Electronic Resource
    Electronic Resource
    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
    Keywords: Alveolar soft-part sarcoma ; Uterus ; Myometrium ; Immunocytochemistry ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01605935
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  • 5
    Electronic Resource
    Electronic Resource
    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
    Keywords: Transgenic mice ; Glucagonomas ; Immunohistochemistry ; Electron microscopy ; Radioimmunoassay
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01600225
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  • 6
    Electronic Resource
    Electronic Resource
    The pathobiology of salivary gland (1991)
    Springer
    Virchows Archiv 418 (1991), S. 387-400 
    Details
    ISSN: 1432-2307
    Keywords: Submandibular gland ; Tissue culture ; Electron microscopy ; Proliferating cells
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01605924
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  • 7
    Electronic Resource
    Electronic Resource
    Degeneration of the corticopontine tract in olivopontocerebellar atrophy (1991)
    Springer
    Virchows Archiv 418 (1991), S. 99-103 
    Details
    ISSN: 1432-2307
    Keywords: Corticopontine tract degeneration ; Olivopontocerebellar atrophy ; Electron microscopy ; Morphometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01600284
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  • 8
    Electronic Resource
    Electronic Resource
    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
    Keywords: Large cell anaplastic lymphoma ; Electron microscopy ; Immunophenotyping
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01605929
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  • 9
    Electronic Resource
    Electronic Resource
    Ultrastructural lipid and glycoconjugate cytochemistry of membranous lipodystrophy (Nasu-Hakola disease) (1991)
    Springer
    Virchows Archiv 419 (1991), S. 137-142 
    Details
    ISSN: 1432-2307
    Keywords: Membranous lipodystrophy ; Nasu-Hakola disease ; Lipid and glyconconjugate ; Cytochemistry ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01600227
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  • 10
    Electronic Resource
    Electronic Resource
    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
    Keywords: Bladder cancer ; Electron microscopy ; Photodynamic therapy ; Photosan ; Phototoxicity ; Tumor selectivity ; Video fluorescence microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00310149
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  • 11
    Electronic Resource
    Electronic Resource
    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
    Keywords: Amyotrophic lateral sclerosis ; Bunina body ; Clarke's nucleus ; Onuf's nucleus ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00305880
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  • 12
    Electronic Resource
    Electronic Resource
    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
    Keywords: Pyramidal neurons ; Motor cortex ; Synapses ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01673266
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  • 13
    Electronic Resource
    Electronic Resource
    The costo-uterine muscle of the rat (1991)
    Springer
    Anatomy and embryology 184 (1991), S. 337-343 
    Details
    ISSN: 1432-0568
    Keywords: Costo-uterine muscle ; Innervation ; Fluorescence histochemistry ; Electron microscopy ; Morphometry ; Rat (Wistar)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00957895
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  • 14
    Electronic Resource
    Electronic Resource
    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
    Keywords: Spinal nerves ; Dorsal column nuclei ; Nerve degeneration ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00942581
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  • 15
    Electronic Resource
    Electronic Resource
    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
    Keywords: Hirano bodies ; Unit lamellae ; Alzheimer's disease ; Rapid-freeze, deep-etch and replica ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00305865
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  • 16
    Electronic Resource
    Electronic Resource
    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
    Keywords: Amyotrophic lateral sclerosis ; Bunina body ; Onuf's nucleus ; Ubiquitin ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00296370
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  • 17
    Electronic Resource
    Electronic Resource
    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
    Keywords: Alzheimer-type dementia ; Senile plaques ; Amyloid β/A4 protein ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00310918
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  • 18
    Electronic Resource
    Electronic Resource
    Microtubule bundles in fish cerebellar Purkinje cells (1991)
    Springer
    Anatomy and embryology 183 (1991), S. 105-110 
    Details
    ISSN: 1432-0568
    Keywords: Initial axon segment ; Microtubules ; Cross-bridges ; Golgi apparatus ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00174390
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  • 19
    Electronic Resource
    Electronic Resource
    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
    Keywords: Elastic-like tissue ; Elasmobranch ; Glomerular capillary wall ; Kidney ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00186436
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  • 20
    Electronic Resource
    Electronic Resource
    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
    Keywords: Primitive neuroectodermal tumor ; Cytokeratin immunohistochemistry ; Double labelling ; Electron microscopy ; Immunoblotting
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00293384
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  • 21
    Electronic Resource
    Electronic Resource
    Recessive ichthyosis congenita type II (1991)
    Springer
    Archives of dermatological research 283 (1991), S. 211-218 
    Details
    ISSN: 1432-069X
    Keywords: Ichthyosis ; Histopathology ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: 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’.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01106104
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  • 22
    Electronic Resource
    Electronic Resource
    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
    Keywords: Savinase ; Proteolytic enzyme ; Human plantar skin ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: 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
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00371819
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  • 23
    Electronic Resource
    Electronic Resource
    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
    Keywords: Corticothalamic projection ; Somatosensory system ; Barrel ; Phaseolus vulgaris ; leucoagglutinin ; Electron microscopy ; Mouse ; Synaptic glomerulus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00228517
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  • 24
    Electronic Resource
    Electronic Resource
    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
    Keywords: Serotonin ; Tyrosine hydroxylase ; Electron microscopy ; Thalamus ; Cat ; Monkey
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00231734
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  • 25
    Electronic Resource
    Electronic Resource
    Corneal edema induced by bis (tributyltin) oxide (1991)
    Springer
    Archives of toxicology 65 (1991), S. 651-655 
    Details
    ISSN: 1432-0738
    Keywords: Bis (tributyltin) oxide ; Corneal edema ; Electron microscopy ; X-ray microanalysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02098031
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  • 26
    Electronic Resource
    Electronic Resource
    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
    Keywords: αNi3S2 ; βNiS ; Rat lymphocytes ; Electron microscopy ; Energy dispersive spectrometry ; Sulfur phosphorus shift ; Biological transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01968967
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  • 27
    Electronic Resource
    Electronic Resource
    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
    Keywords: Electron microscopy ; three-dimensional vision ; surface reconstruction ; stereo ; shape from shading ; dynamic programming
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01815304
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  • 28
    Electronic Resource
    Electronic Resource
    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
    Keywords: Soluble NAD-dependent hydrogenase ; Alcaligenes eutrophus ; Nocardia opaca ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00252217
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  • 29
    Electronic Resource
    Electronic Resource
    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
    Keywords: Acetazolamide ; Carbonic anhydrase activity ; Choroid plexus ; Electron microscopy ; Serotonin ; Tetrabenazine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00263186
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  • 30
    Electronic Resource
    Electronic Resource
    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
    Keywords: Spermiogenesis ; Spermatids ; DNA ; Immunocytochemistry ; Electron microscopy ; Bovine ; Mouse ; Rabbit
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00340875
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  • 31
    Electronic Resource
    Electronic Resource
    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
    Keywords: Calbindin ; Neurohypophysis ; Development, ontogenetic ; Immunohistochemistry ; In-situ hybridization ; Electron microscopy ; Rat (Wistar)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00318188
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  • 32
    Electronic Resource
    Electronic Resource
    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
    Keywords: Xenografted human carcinomas ; Basal lamina ; Development, following heterotransplantation ; Electron microscopy ; Immunofluorescence microscopy ; Man ; Mouse (NMRI, nu/nu)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00318598
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  • 33
    Electronic Resource
    Electronic Resource
    Initiation of acellular extrinsic fiber cementum on human teeth (1991)
    Springer
    Cell & tissue research 263 (1991), S. 311-324 
    Details
    ISSN: 1432-0878
    Keywords: Dental root surface ; Periodontal fiber fringe ; Dentino-cemental junction ; Electron microscopy ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00318773
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  • 34
    Electronic Resource
    Electronic Resource
    Establishment of acellular extrinsic fiber cementum on human teeth (1991)
    Springer
    Cell & tissue research 263 (1991), S. 325-336 
    Details
    ISSN: 1432-0878
    Keywords: Cementum ; Fiber fringe ; Periodontal ligament fibers ; Dentino-cemental junction ; Electron microscopy ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00318774
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  • 35
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    Electronic Resource
    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
    Keywords: Erythroblast ; Cytokinesis ; Cytoplasmic bridge ; Fetal liver ; Erythropoiesis ; Electron microscopy ; dd Mice
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00313958
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  • 36
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    Electronic Resource
    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
    Keywords: Oocytes ; Meiosis ; Energy metabolism ; Protein synthesis ; Nuclear envelope ; Electron microscopy ; Mouse (Swiss)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00318144
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  • 37
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    Electronic Resource
    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
    Keywords: Blood-brain barrier ; Glia ; Meninges ; Electron microscopy ; Skate, Raja erinacea (Elasmobranchii)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: 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.
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    URL: http://dx.doi.org/10.1007/BF00318145
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  • 38
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    Electronic Resource
    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
    Keywords: Basement membrane ; Proximal tubule ; Hydraulic pressure ; Mechanical stress ; Electron microscopy ; Rat (Sprague-Dawley)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00678706
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  • 39
    Electronic Resource
    Electronic Resource
    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
    Keywords: Pancreas, endocrine ; Islets of Langerhans ; Immunocytochemistry ; Endocrine cells four types ; Electron microscopy ; Sminthopsis crassicaudata (Marsupialia)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00318415
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  • 40
    Electronic Resource
    Electronic Resource
    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
    Keywords: Transverse (T-) tubules ; Muscle, cardiac ; Electron microscopy ; Morphometry ; Rabbit (Lagomorpha)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00313966
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  • 41
    Electronic Resource
    Electronic Resource
    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
    Keywords: Tooth pulp ; NGF receptor ; Calcitonin gene-related peptide ; Substance P ; Neuropeptide Y ; Immunocytochemistry ; Electron microscopy ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00313969
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  • 42
    Electronic Resource
    Electronic Resource
    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
    Keywords: Adrenal autotransplants ; Sodium restriction ; Mineralocorticoid hormones ; Electron microscopy ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00318136
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  • 43
    Electronic Resource
    Electronic Resource
    The endocrine pancreas of glucagon-and somatostatin-immunized rabbits (1991)
    Springer
    Cell & tissue research 265 (1991), S. 261-273 
    Details
    ISSN: 1432-0878
    Keywords: Endocrine pancreas ; Immunization ; Insulin ; Glucagon ; Somatostatin ; Electron microscopy ; Rabbit (Chinchilla, Ch: b Ch)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00398074
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  • 44
    Electronic Resource
    Electronic Resource
    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
    Keywords: Electron microscopy ; Scanning electron microscopy ; Lectin-gold particles ; Cytology ; Glycoproteins ; Imaginal discs ; Tissue culture ; Plodia interpunctella (Insecta)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00398084
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  • 45
    Electronic Resource
    Electronic Resource
    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
    Keywords: Isolated heart ; Extended perfusion ; Oxygen-carrying solutions ; Electron microscopy ; Preservation and edema
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02125098
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  • 46
    Electronic Resource
    Electronic Resource
    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
    Keywords: Adiantum capillus veneris ; Meristematic root cells ; Microtubule organization ; Immunofluorescence microscopy ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01322288
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  • 47
    Electronic Resource
    Electronic Resource
    Repair of 8-methoxypsoralen photoinduced cross-links in yeast (1991)
    Springer
    Molecular genetics and genomics 228 (1991), S. 335-344 
    Details
    ISSN: 1617-4623
    Keywords: Saccharomyces cerevisiae ; DNA interstrand cross-links ; DNA repair ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00260625
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  • 48
    Electronic Resource
    Electronic Resource
    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
    Keywords: Creutzfeldt-Jakob disease ; Electron microscopy ; Myelinated axon
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00143137
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  • 49
    Electronic Resource
    Electronic Resource
    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
    Keywords: Merkel cell carcinoma ; Neuroendocrine carcinoma ; Bowen's disease ; Immunohistochemistry ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00627629
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  • 50
    Electronic Resource
    Electronic Resource
    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
    Keywords: Vesicle ; Freeze-fracture ; Electron microscopy ; Size distributions ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: 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.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jemt.1060170409
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  • 51
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    Electronic Resource
    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
    Keywords: Biocytin ; Electron microscopy ; Diaminobenzidine ; Hippocampus ; Horseradish peroxidase ; Spines ; Varicosities ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: 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.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jemt.1060180112
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  • 52
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    Electronic Resource
    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
    Keywords: BrdU incorporation ; Cultured cells DNA replication ; Electron microscopy ; EM immunocytochemistry ; Immunocytochemistry ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: 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.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jemt.1060180202
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  • 53
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    Electronic Resource
    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
    Keywords: Spermatogenesis ; Sertoli cells ; Leydig cells ; Electron microscopy ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: 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.
    Additional Material: 19 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jemt.1060190208
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  • 54
    Electronic Resource
    Electronic Resource
    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
    Keywords: Collagen ; Mineral ; Calcification ; Tendon ; Electron microscopy ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: 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.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jemt.1060180308
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  • 55
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    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
    Keywords: Electron microscopy ; Lowicryl ; Herpes simplex virus type 1 infection ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: 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.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jemt.1060180403
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    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
    Keywords: Myocardium ; Blood vessels ; Electron microscopy ; Fixation ; Methods ; Ischaemia ; Reperfusion ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: 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.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jemt.1060190405
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    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
    Keywords: Immunocytochemistry ; Electron microscopy ; In situ hybridization ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: 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.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jemt.1060190107
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  • 58
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    Electronic Resource
    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
    Keywords: Endothelium ; Immunocytochemistry ; Electron microscopy ; Lectins ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: 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.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jemt.1060190306
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    Electronic Resource
    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
    Keywords: Electron microscopy ; Flat embedding ; Cell culture monolayers ; Ultramicrotomy section plane ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: 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.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jemt.1060170408
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  • 60
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    Electronic Resource
    Time sequence and site of fluid accumulation in experimental neurogenic pulmonary edema (1976)
    Springer
    Research in experimental medicine 168 (1976), S. 219-227 
    Details
    ISSN: 1433-8580
    Keywords: Initial phase of neurogenic pulmonary edema ; Perfusion fixation ; HRP ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The initial phase of pulmonary edema development following intracranial pressure elevation was studied by means of transmission electron microscopy. Using perfusion fixation and application of a blood tracer (HRP horseradish peroxidase) the time sequence and site of fluid leakage out of pulmonary vessels was demonstrated: - passage of edema fluid through intercellular clefts of alveolar capillary endothelium - edema accumulation in alveolar interstitial tissue - draining of edema fluid from the alveolar septum to the interstitium of terminal bronchioli and to lymphatic vessels. An early interepithelial fluid leakage out of the alveolar wall remains questionable.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01851320
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  • 61
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    Metabolism and ultrastructure in ovaries of alloxan-diabetic juvenile rats (1976)
    Springer
    Archives of gynecology and obstetrics 220 (1976), S. 199-208 
    Details
    ISSN: 1432-0711
    Keywords: Rat ovaries ; Diabetes mellitus ; Alloxan ; ATP/ADP ; Lactate/pyruvate ; NADP/NADPH ; Glucose ; Protein content ; Hydrogen-coveying enzymes ; alkal. phosphatase ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Es wurde der Einfluß eines alloxan-induzierten Diabetes mellitus auf den Stoffwechsel und die Ultrastruktur juveniler Rattenovarien untersucht. Der Diabetes mellitus bewirkte folgende Änderungen imStoffwechsel: Abfall der Konzentration von ATP und NADPH, Anstieg des Lactat/Pyruvat-Quotienten über 40, Abfall des ATP/ADP-Quotienten unter 1, Aktivitätsminderung der wasserstoffübertragenden Enzyme G-6-DH, Isocitrat-DH, Malat-DH, Aktivitätszunahme der alkalischen Phosphatase, Erniedrigung des Proteingehaltes.Ultrastruktur: Nahezu vollständiges Verschwinden des rauhen endoplasmatischen Reticulums, Schrumpfung der Mitochondrien, Reduktion der cristae und Kondensation der Matrix. Das glatte endoplasmatische Reticulum bleibt unverändert, der Golgi-Komplex ist in seiner Ausdehnung reduziert. Leichte Extrahierbarkeit der Lipiddepots. Die Befunde sprechen für eine Hemmung der oxydativen Phosphorylierung sowie für eine Beeinträchtigung des Steroid- und Proteinstoffwechsels.
    Notes: Summary Tests were carried out on the influence of alloxan-induced diabetes mellitus on the metabolism and the ultrastructure of ovaries of juvenile rats. The diabetes mellitus caused the following changes in themetabolism: reduction in the concentration of ATP and NADPH, increase in the lactate/pyruvate quotient to above 40, reduction in the ATP/ADP quotient to below 1, reduction in the level of activity of the hydrogen-conveying enzymes G-6-P-dehydrogenase, isocitrate dehydrogenase and malate dehydrogenase, increase in the level of activity of the alkaline phosphatase, reduction of the protein content. Ultrastructure almost complete disappearance of the rough endoplasmic reticulum, shrinkage of the mitochondria, reduction of the cristae and condensation of the matrix. The smooth endoplasmic reticulum remains unchanged, the extent of the Golgi-complex is reduced. Easy removal of the lipid deposits.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00667748
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    Ultrastructural study of testis in testicular feminization (1976)
    Springer
    Archives of gynecology and obstetrics 221 (1976), S. 277-287 
    Details
    ISSN: 1432-0711
    Keywords: Electron microscopy ; Endocrinology ; Pathology ; Testicular feminization ; Testis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Testicular tissue was investigated by electron microscopy in a case of testicular feminization. The seminiferous tubules were lined by spermatogonia and by Sertoli cells. Spermatocytic maturation was not observed. Leydig cells were numerous and contained well developed, abundant vesicular smooth-surfaced endoplasmic reticulum and large mitochondria with tubulovesicular cristae. Reinke crystalloids were absent. The ultrastructural findings were consistent with the assumption that Leydig cells were under adequate stimulation and were in a stage of active secretion. Hence, the results seem to indicate that testicular endocrine function was maintained in the studied case.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00667021
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  • 63
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    Effect of peripheral axotomy on the fine structure and histochemistry of the Rolando substance: Degenerative atrophy of central processes of pseudounipolar cells (1976)
    Springer
    Experimental brain research 26 (1976), S. 73-87 
    Details
    ISSN: 1432-1106
    Keywords: Rolando substance ; Degeneration ; Atrophy ; Axotomy ; Histochemistry ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Disappearence of fluorid-resistant acid phosphatase activity from the ipsilateral Rolando substance after transection of the peripheral nerve, is shown to be due to the cessation of enzyme supply from dorsal root ganglion cells to their central terminals. This is accompanied by (or ensues in consequence of) a fine structural derangement of these terminals (“degenerative atrophy”). Fine structural alterations of axon terminals undergoing degenerative atrophy, though similar to some extent to those seen during early phases of a Wallerian degeneration, are markedly different. Also myelinated nerve fibers, both in the dorsal horn and in dorsal columns, are affected by degenerative atrophy. This important, new trophical feature of sensory ganglion cells suggests a delicate metabolic balance between peripheral and central axonal branches of bipolar (pseudounipolar) cells. Degenerative atrophy raises serious implications in evaluating hodological experiments based upon Wallerian degeneration and offers new perspectives for theoretical and clinical neurology.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00235250
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  • 64
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    Electronic Resource
    An electron microscopic study of plasmatic arterionecrosis in the human cerebral arteries (1976)
    Springer
    Virchows Archiv 369 (1976), S. 181-190 
    Details
    ISSN: 1432-2307
    Keywords: Cerebral hemorrhage ; Cerebral artery disease ; Plasmatic arterionecrosis ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary An electron microscopic study of the intracerebral arteries from 9 hypertensive cases was performed in order to elucidate the morphogenesis of the plasmatic arterionecrosis which was considered to be the direct cause of hypertensive intracerebral hemorrhage. In the preceding stage of the arterial lesions, marked necrosis of medial smooth muscle cells and increase of basement membrane-like substance in the intima and media were observed. The lumina of these arteries were slightly dilated. The dilatation and hemodynamic factors were supposed to cause endothelial injury resulting in blood plasma insudation into the intima through the opened spaces between endothelial cells. The insudated blood plasma dispersed and dissolved the basement membrane-like substance, collagen and elastic fibers in the arterial wall, leading to the development of the plasmatic arterionecrosis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00427707
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  • 65
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    Electronic Resource
    Stereology of liver biopsies from healthy volunteers (1976)
    Springer
    Virchows Archiv 371 (1976), S. 251-263 
    Details
    ISSN: 1432-2307
    Keywords: Human liver ; Electron microscopy ; Stereology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The stereologioal model and the base-line data of normal human liver needle biopsy-specimens are presented. Four reference systems were introduced: 1 cm3 of liver tissue, 1 cm3 of hepatoeyte, 1 cm3 of hepatocytic cytoplasm and the volume of an average “mononuclear” hepatocyte. The sampling was done at three levels of magnification (1,000 ×, 5,000 × and 10,000 ×). A lobular differentiation was not considered. The baseline data show strikingly small variations (s.e. less than 10%) within the individual biopsy specimen and within the group of four biopsies. There is no principal difference between human beings presented here, rats, mice and dogs. Only the mean individual volume of human hepatocytes is clearly larger than in rodents. The problems and limitations of stereological work on liver biopsy specimens are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00433072
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  • 66
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    Electronic Resource
    Hairy cell leukemia (1976)
    Springer
    Virchows Archiv 370 (1976), S. 273-289 
    Details
    ISSN: 1432-2307
    Keywords: Bone marrow biopsy ; Hairy cell leukemia ; Differential diagnosis ; Myelofibrosis ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In 24 patients with hairy cell leukemia, histological and fine structural findings from biopsies of the bone marrow are reported and their validity is compared with other diagnostic procedures available. Diagnosis by light microscopy of anterior iliac crest biopsies obtained by the method of myelotomy is possible with a high degree of accuracy. The differentiation of hairy cell leukemia from other myelo- or lymphoproliferative disorders based on cytomorphology as well as patterns of growth is emphasized. Morphological differences between fibrosis in this entity and other lesions such as malignant lymphomas, Hodgkin's disease, osteomyelofibrosis and -sclerosis are emphasized. Electron microscopy of the bone marrow shows single fibroblastic cells with numerous slender cytoplasmic processes randomly dispersed among the hairy cells. These fibroblasts are probably responsible for the synthesis of the reticulin and collagen fibres in their surroundings. Moreover fine structure of the hairy cells demonstrates pinocytic activity but no apparent phagocytosis in contrast to the phagocytic reticulum cells (histiocytes, macrophages). In the bone marrow the precursor cells and the many immature forms of hairy cells exhibit an overall lymphocytoid appearance during their maturation, suggesting a lymphocytic origin.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00445773
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  • 67
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    Experimentell induzierte Herzmuskelfasernekrosen nach Praemedikation mit Strophanthin (1976)
    Springer
    Virchows Archiv 370 (1976), S. 141-150 
    Details
    ISSN: 1432-2307
    Keywords: Angiotensin ; Catecholamine ; Strophanthin ; Rat heart ; Myocardial necroses ; Optical microscopy ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Bei der Ratte nehmen die durch Angiotensin induzierten Herzmuskelfasernekrosen (75 mg/kg s.c. und i.p.) unter Strophanthin-Praemedikation (2 × 10−2 mg/kg i.p.) an Zahl und Ausmaß ab. Darüberhinaus ändert sich der elektronenmikroskopische Befund: Die alleinige Gabe von Angiotensin bewirkt eine Vakuolisation der Mitochondrion und eine Dilatation des endoplasmatischen Reticulum ohne Alteration der Myofibrillen. Die kombinierte Gabe von Strophanthin und Angiotensin führt zu einer primären Zerstörung der Myofibrillen, ohne daß Mitochondrien und tubuläres System sichtbar verändert werden. Der Schutzmechanismus des Strophanthin wird im Sinne einer Ökonomisierung des Zellstoffwechsels bei relativer coronarieller Insuffizienz diskutiert, welche durch die starke vasokonstriktorische Wirkung des Angiotensin ausgelöst wird.
    Notes: Summary Number and degree of angiotensin-induced heart muscle necroses in the rat (75 mg/kg body weight) are diminuished by premedication with strophanthin (2 × 10−2 mg/kg body weight). The electron-microscopic findings are also changed: the application of angiotensin only results in vacuolization of mitochondria and a dilatation of the endoplasmatic reticulum while myofibrils are unaltered. Angiotensin in combination with strophanthin has a direct destructive effect on the myofibrils without evident changes of the mitochondria and the tubular system of the heart. The protective action of Strophanthin on the heart muscle cell is discussed in the sense of an economization of the cellular metabolism under conditions of relative coronary insufficiency, induced by the vasoconstructive effect of angiotensin.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00430810
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    On the fungitoxicity of some new thiocyanatopyrazole derivatives: Electron microscopical study in trichophyton mentagrophytes (1976)
    Springer
    Mycopathologia 58 (1976), S. 39-47 
    Details
    ISSN: 1573-0832
    Keywords: Trichophyton mentagrophytes ; Thiocyanatopyrazole derivatives ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Four thiocyanatopyrazole derivatives were synthesized and their fungistatic activity was demonstrated in vitro against a number of dermatophytic fungi. In Trichophyton mentagrophytes, the most active compound induced an unusual increase of the plasma membrane with production of intra and extracytoplasmic complexes, a deterioration of nuclear and mitochondrial membranes and a formation of autophagic-like vacuoles. Plasmolysis, accompanied by an almost complete disorganization of cytoplasmic structures, seemed to be the final event. A possible mechanism of action of the compounds was discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00493592
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  • 69
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    Electronic Resource
    Ultrastructure of the labyrinth in the rat full-term placenta (1976)
    Springer
    Anatomy and embryology 149 (1976), S. 123-148 
    Details
    ISSN: 1432-0568
    Keywords: Rat-placenta ; Gap junctions ; Electron microscopy ; Freeze-fracturing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The placental labyrinth of the chorioallantoic placenta of the rat was studied with transmission and scanning electron microscopy. Full-term placentas were investigated after perfusion fixation from the maternal and fetal circulation, including thin-sectioning and freeze-fracturing. The labyrinthal three-dimensional structure was found not to be trabecular but spongious lamellar. We propose a division of the lamellae into three groups—the first, second, and third order. The trophoblastic layers are described in detail, showing a cellular layer I and two syncytial layers II and III. Layer I is found to be fenestrated and highly permeable. Layers II and III are connected by extended gap junction areas. It is suggested that the gap junctions function as a molecular sieve and represent the limiting barrier in diaplacental transport of the choriollantoic placenta. Fetal capillaries are fenestrated and endothelial cells are connected by tight junctions. The functional significance of the morphologic findings is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00317893
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  • 70
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    Electronic Resource
    Ultrastructure of Lewy bodies in the stellate ganglion (1976)
    Springer
    Acta neuropathologica 34 (1976), S. 183-197 
    Details
    ISSN: 1432-0533
    Keywords: Lewy body ; Electron microscopy ; Parkinsonism ; Dense core vesicles ; Catecholamines ; Mitochondrial inclusions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The Lewy body, a characteristic nerve cell inclusion in idiopathic parkinsonism, was examined by electron microscopy in the stellate ganglion, obtained from 9 patients at autopsy. Three main forms of Lewy bodies or Lewy body-related structures were demonstrated: A. Rare filamentous Lewy bodies, similar to Lewy bodies in the central nervous system. B. Granular Lewy bodies in nerve cell processes. C. Abnormal nerve cell processes, filled with heterogenous material. Large dense core vesicles were prominent in the last 2 forms. None of these abnormalities were found in 2 control groups consisting of 9 parkinsonism cases without central nervous system Lewy bodies, and 17 cases without parkinsonism. The filamentous Lewy body (type A) was found in the perikaryon and was surrounded by neuromelanin, whereas the other forms (type B and C) were seen in nerve cell processes. Mitochondrial inclusions, present mainly, but not exclusively, in neuromelanin-containing cells, were not related to Lewy body formation or to parkinsonism.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00688674
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  • 71
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    Electronic Resource
    Damage of skeletal muscle in rats by immunoglobulins (1976)
    Springer
    Acta neuropathologica 34 (1976), S. 207-218 
    Details
    ISSN: 1432-0533
    Keywords: Immunomyopathy ; Muscle disease ; Electron microscopy ; Experimental muscle pathology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary An experimental model of the autoimmune process was developed to study the ultrastructural aspects of immunomyopathies. Every type of muscle fibre organelle was affected and the severity of injury increased in direct proportion to time following immunization. It is suggested that ultrastructural methods are useful in studies concerned with the analysis of structural aspects of experimental immunomyopathies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00688676
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  • 72
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    Electronic Resource
    In vitro characteristics of a sacrococcygeal chordoma maintained in tissue and organ culture systems (1976)
    Springer
    Acta neuropathologica 35 (1976), S. 13-25 
    Details
    ISSN: 1432-0533
    Keywords: Chordoma ; Tissue and organ culture ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Explants of a human sacral chordoma were successfully maintained on collagen-coated coverslips, gelfoam sponge matrices, and Millipore filter platforms for up to 30 days. Tumor cells cultured on collagen-coated coverslips became increasingly vacuolated whereas those maintained in organ culture were entirely free of vacuoles after 22 days in vitro. A single basic tumor cell, small and polygonal with a large central spherical nucleus and abundant endoplasmic reticulum and Golgi apparatus, was recognized. Vacuoles were formed as the result of the progressive expansion of smooth endoplasmic reticulum. Coalescence of these vacuoles produced the physaliferous cell of light microscopy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00688940
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  • 73
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    Electronic Resource
    Esthésioneurocytome olfactif (1976)
    Springer
    Acta neuropathologica 35 (1976), S. 139-150 
    Details
    ISSN: 1432-0533
    Keywords: Electron microscopy ; Olfactory esthesioneurocytoma ; Neurosecretory granules ; Microtubules ; Dystrophic axons
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary One case of malignant tumour of the left nasal cavity is reported in a woman 56 year old, affected by the disease 24 years. Numerous recurrences appeared and various histological diagnoses were performed. At the last surgery, the tumour invaded the ethmoïd and was a typical olfactory esthesio-neurocytoma. By electron microscopy, mature ganglion cells with dense cored vesicles (neurosecretory granules) were densely packed. Neuritic processes with microtubules were rarely normal in size and their content was most often abnormal; furthermore dystrophic axons were noted in great number.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00690560
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  • 74
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    Electronic Resource
    Light and electron microscopic investigations on a transplantable tumour of the rat, induced by transplacental administration of ENU (ethylnitrosourea) (1976)
    Springer
    Acta neuropathologica 36 (1976), S. 177-184 
    Details
    ISSN: 1432-0533
    Keywords: Neurinoma ; ENU ; Prenatal carcinogenesis ; Transplantability ; Metastases ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary With a single dose of 80 mg/kg ENU, a tumour originating from the trigeminal nerve was induced transplacentally in the offspring of a Sprague-Dawley rat. The neoplasm diagnosed as a neurinoma, was transplanted over 20 passages to 5 six-month-old Sprague-Dawley rats in each case. During this time, the biological behaviour of the tumour as well as its histological appearance were followed. Ultrastructural observations were made of the 20th passage. The tumour caused multiple metastases in the lung and in the lymph nodes of the neck in 30 animals. Recurrences were formed within a week, metastases of the lung appeared from then on in all cases. During the time of transplantation, the neurinoma dedifferentiated histologically so markedly that it was no longer possible to classify the neoplasm as a neurogenous tumour after 20 passages. Ultrastructurally, poorly differentiated Schwann cells could nervetheless be recognized.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00685279
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  • 75
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    Electronic Resource
    “PKU Bodies”: Characteristic inclusions in the brain in phenylketonuria (1976)
    Springer
    Acta neuropathologica 36 (1976), S. 295-305 
    Details
    ISSN: 1432-0533
    Keywords: PKU bodies ; Demyelination ; Dysmyelination ; Neuroglia ; Inborn errors of metabolism ; Phenylketonuria ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The ultrastructure of various inclusions within oligodendroglial cells in the brains from two phenylketonuric patients was studied. Characteristic lamellar, oval, slightly irregular inclusions measured between 0.5 and 2 micra in diameter and were bounded by a single membrane. The longitudinal and transverse lamellae of these inclusions had a distinct pattern. In analogy to lamellated but different inclusions of other diseases, these structures were termed “PKU bodies”. Various possibilities that would explain the morphogenesis of the PKU bodies and other inclusions in the oligodendroglial cells, and the significance of these findings, are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00699635
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  • 76
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    Sequence of morphological alterations in the nervous system of metachromatic leucodystrophy (1976)
    Springer
    Acta neuropathologica 36 (1976), S. 369-379 
    Details
    ISSN: 1432-0533
    Keywords: Leukodystrophy, metachromatic ; Prenatal diagnosis ; Sulphatide accumulation ; Myelination, central, peripheral ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Light and electronmicroscopic findings are reported in a case of metachromatic leukodystrophy diagnosed prenatally who died after iatrogenic abortion during the 23th week of gestation. The brain of this foetus was not yet myelinated while the spinal cord showed early, and the peripheral nerves advanced myelination. The onset and the degree of myelination were similar as in a normal foetus of the same age. Ultrastructurally there was evidence of sulphatide storage before the beginning of myelination. During myelination lysosomal storage material, staining metachromatically in acid cresyl violet preparations, appeared in oligodendrocytes and Schwann cells. Besides sulphatide storage material, prominent amounts of neutral lipids were found in oligodendrocytes. Myelin breakdown was encountered very seldom.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00699642
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  • 77
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    Development of onion bulb neuropathy in the Trembler mouse (1976)
    Springer
    Acta neuropathologica 36 (1976), S. 137-152 
    Details
    ISSN: 1432-0533
    Keywords: Trembler mouse ; Peripheral neuropathy ; Electron microscopy ; Morphometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The Trembler mouse is a neurological mutant showing dominant inheritance. The peripheral nerves show a delay in myelination, segmental demyelination and the development of an onion bulb neuropathy. Using electron microscopy a comparative morphometric study of nerve fibres in the sciatic nerve in normal and Trembler mice was made. The animals ranged in age from 3 days to adult. The following features were noted: 1. Mean axon diameters of the Trembler mice were smaller than normal at all ages. 2. Myelination was delayed and myelin was thinner than normal in the Trembler mice. 3. The ratio of myelin thickness to axon diameter was reduced in Trembler mice. 4. There were no significant quantitative or qualitative differences observed between middle and distal levels of Trembler nerves. The balance of evidence from these findings and the previous morphological studies is in keeping with the suggestion that the primary lesion resides in the Schwann cell.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00685276
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  • 78
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    The target phenomenon in human muscle (1976)
    Springer
    Acta neuropathologica 34 (1976), S. 329-338 
    Details
    ISSN: 1432-0533
    Keywords: Muscle pathology ; Target muscle fibre ; Targetoid muscle fibre ; Histochemistry ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A large number of target fibres is observed in a muscle biopsy from a patient with an acute flaccid paraplegia of the lower limbs due to a polyneuroradiculopathy of unknown origin. With the electron microscope up to 4 structural zones are seen in the target fibers. The histochemical and ultrastructural observations in this case, suggest that the “target fibre” phenomenon is due to a disturbed trophic influence of the nervous system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00696562
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  • 79
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    Morphological differences between the atrophied small muscle fibres in amyotrophic lateral sclerosis and Werdnig-Hoffmann disease (1976)
    Springer
    Acta neuropathologica 34 (1976), S. 321-327 
    Details
    ISSN: 1432-0533
    Keywords: Muscle fibres ; Amyotrophic lateral sclerosis ; Werdnig-Hoffmann disease ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Muscle biopsies from 5 cases of Werdnig-Hoffmann disease and 4 cases of ALS were investigated by histology and electronmicroscopy. The differences in morphology found in the atrophic muscle fibres in ALS and in W.H. diesease consisted mainly in the shape and structure of their cells and the number of the nuclei. Atrophic muscle fibres irregular in shape and size with degenerative changes and accumulated nuclei observed in ALS were markedly different from the picture of the fibres in W.H. disease. The presence of small muscle cells uniform diameter with well preserved architecture and single nuclei and numerous myotube-like cells seem to indicate a foetal defect in children with W.H. disease.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00696561
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  • 80
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    Renflement fusiforme d'origine mécanique d'un nerf périphérique. Étude anatomique (1976)
    Springer
    Acta neuropathologica 35 (1976), S. 47-54 
    Details
    ISSN: 1432-0533
    Keywords: Entrapment neuropathy ; Fusiform nerve enlargement ; Segmental demyelination ; Axonal changes ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary This paper reports on the study of a symptomless fusiform enlargement of the superficial peroneal nerve. The swelling was located in the part of the nerve passing through the aponevrosis. On incision of the epineurium small swellings were seen in the nerve fascicles. A fascicular biopsy was done and the fascicles studied by teasing and by optic and electron microscopy. Isolated nerve fiber study gave evidence of segmental demyelinisation with subsequent remyelinisation in almost all the myelinated fibers. These abnormalities were only encountered in the swollen part of the fascicle. A striking proliferation of cells was demonstrated in isolated fibers by counter-staining with hematoxylin. Electron microscopy showed primary demyelinsation and cellular proliferation affecting Schwann-cells (without onion bulb formations), fibroblasts and giant-vacuolated histiocytes. There was also a massive increase of endoneurial fluid. A few Büngner bands were seen. These rare abnormalities appear to be caused by chronic irritation of the nerve in its passage through the aponebrosis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00688942
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  • 81
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    Studies on experimental malignant nerve sheath tumors maintained in tissue and organ culture systems (1976)
    Springer
    Acta neuropathologica 35 (1976), S. 27-45 
    Details
    ISSN: 1432-0533
    Keywords: Experimental malignant Schwannomas ; Melanin and melanogenesis ; Tissue and organ culture ; Electron microscopy ; Pigmented nerve sheath tumors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Four melanin pigment-containing intracranial tumors were found in three Long-Evans rats in the course of experimental oncogenesis by transplacental ethylnitrosourea (ENU). One of them was a leptomeningeal melanoma. Aside from the presence of scattered melanin-pigmented cells, the other three had the typical histological features of ENU-induced malignant nerve sheath tumors. Two of the three tumors were studied by electron microscopy and in tissue and organ culture systems. One of them demonstrated progressive melanogenesis in vitro; the other failed to produce more melanin and showed increasing differentiation, with a Schwannoma-like pattern by light microscopy. Melanosomes and premelanosomes were identified in both tumors by electron microscopy; the other fine structural features were those of malignant Schwannomas. These observations are relevant to the controversy on the histogenesis of pigmented nerve sheath tumors occasionally encountered in man and on the relationship of these tumors to pigmented nevi. The findings in the present study support the view of Masson that neoplastic nerve sheath cells are capable of melanogenesis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00688941
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  • 82
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    Ultrastructure of the Gunn rat substantia nigra I. Cytoplasmic changes (1976)
    Springer
    Acta neuropathologica 35 (1976), S. 93-107 
    Details
    ISSN: 1432-0533
    Keywords: Substantia nigra ; Gunn rat ; Complex membranous bodies ; Bilirubin ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The substantia nigra of various aged hyperbilirubinemic (Gunn) rats was studied by means of electron microscopy. The cytological features observed in the neuronal somata were the presence of (1) complex membranous bodies (CMBs), (2) dilated cisternae of granular endoplasmic reticulum, (3) single membrane bound vacuoles and (4) enlarged mitochondria. Nearly every neuronal soma studied in two week old Gunn rats contained CMBs, which consisted of several layers of membrane that usually, but not always, surrounded small islands of cytoplasm. On occasion CMBs were seen to be directly connected with granular endoplasmic reticulum and, in a few instances, they were located within a cistern of endoplasmic reticulum. There were significantly fewer CMBs in the neuronal somata of adult Gunn rats. They were located peripherally in the somata or in the proximal portions of dendrites. Furthermore, in these animals the cytoplasm appeared normal and did not exhibit the features commonly seen in younger animals. Only a few hyperchromatic neurons were observed and no pronounced gliosis was evident. Therefore it is assumed that the majority of substantia nigra neurons recovered from the toxic effect of bilirubin or that the concentration of bilirubin deposited in the substantia nigra is not sufficient to be lethal. The hypothesis that is considered is that CMBs represent autophagic activity which results from exposure of neurons to bilirubin. The adjacent neurites and glia did not demonstrate the cytoplasmic changes that were characteristic of the neuronal somata.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00690556
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  • 83
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    Whipple's disease of the central nervous system (1976)
    Springer
    Acta neuropathologica 36 (1976), S. 31-38 
    Details
    ISSN: 1432-0533
    Keywords: Whipple's disease ; Central nervous system ; Granulomatous infiltration ; Electron microscopy ; Bacillary bodies
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Whipple's disease presenting as a neurological disease without gastrointestinal symptoms is an unusual occurrence. A 40 year old man suffered hypersomnia, memory loss and progressive ophthalmoplegia for 6 months prior to death. The nature of his disease was not established during life. Extensive granulomatous inflammation affecting the hypothalamus, hippocampus and periaqueductal gray matter of the brain was found to represent Whipple's disease by electron microscopy. Characteristic lesions were also present in spleen, mesenteric lymph nodes, small intestine and myocardium. Bacillary bodies and membranous inclusions similar to those seen in visceral lesions of Whipple's disease were present in macrophages. The findings supported the theory of direct involvement of the central nervous system by bacilli rather than a metabolic origin for the lesions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00685145
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  • 84
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    Studies on experimental malignant nerve sheath tumors maintained in tissue and organ culture systems II. Electron microscopy observations (1976)
    Springer
    Acta neuropathologica 34 (1976), S. 293-310 
    Details
    ISSN: 1432-0533
    Keywords: Experimental malignant Schwannomas ; Organ culture ; Electron microscopy ; Differentiation ; Microtubules ; Basal lamina ; Perineurial fibroblasts
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The sequential electron microscopic features of six malignant nerve sheath tumors (three cranial and three spinal) induced in rats by transplacental ethylnitrosourea and maintained in organ culture systems were compared with those of a human acoustic Schwannoma similarly cultured. After 4 weeks in vitro, the malignant tumor cells often showed progressive elongation of their processes, with the development of an interdigitating pattern resembling that seen in well-differentiated Schwannomas. This was accompanied by an increase of microtubules. Basal lamina formation, less well-developed and less complete than in the benign Schwannoma in this study, was maintained in culture. Some explants demonstrated an increase in number and width of collagen fibrils, accompanied by a relative concomitant decrease of intercellular basement membrane material. The malignant tumor cells also showed numerous micropinocytotic vesicles and various junctional complexes, which are characteristic of perineurial cells. Since the origin of the experimental tumors from adult Schwann cells seems well established, this apparent contradiction is best resolved by the concept that Schwann cells and perineurial fibroblasts are functional variants of the same cell type.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00696559
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  • 85
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    Vacuolation of oligodendroglia in neoplastic perifocal edema (1976)
    Springer
    Acta neuropathologica 35 (1976), S. 1-12 
    Details
    ISSN: 1432-0533
    Keywords: Cytoplasmic vacuole ; Oligodendroglia ; Brain edema ; Metastatic carcinoma ; Glioma ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Vacuolation of oligodendroglia, a new type of cytopathological change, has been described. The change is observed frequently at the perifocally edematous cerebral white matter adjacent to the metastatic lesions of carcinoma from the lung in all three cases examined. It is also present occasionally in association with astrocytoma. This condition is characterized by swelling of oligodendroglias due to numerous cytoplasmic vacuolations which contain the material identical with that of the extracellular edema fluid. In such cells, the nucleus is displaced and deformed by vacuoles but the nuclear chromatin and envelopes are arranged normally. By occupation of numerous large vacuoles the cytoplasm is divided into small areas, but the individual organelles are only minimally altered. The oligodendroglial vacuolation seems to be a phagocytic response to the edema fluid which contains proteinous macromolecules derived from blood-borne protein and necrotic material of brain tissue and neoplastic cells. The vacuolation may result in some oligodendroglial dysfunction in maintenance of myelin and probably be related with diffuse loss of myelin sheath in the longstanding brain edema secondary to neoplastic invasion. The vacuolated cells can be identified with light and electron microscopes in Epon-embedded sections of surgically removed tissue but not in paraffin sections.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00688939
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  • 86
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    Dynamic aspects of peripheral nerve changes in progressive neural muscular atrophy (1976)
    Springer
    Journal of neurology 211 (1976), S. 111-124 
    Details
    ISSN: 1432-1459
    Keywords: Peripheral nerve ; Peroneal muscular atrophy ; Nerve biopsy ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Bei 2 Patienten mit progressiver neuraler Muskelatrophie wurden Nervenbiopsien jeweils in einem frühen und in einem fortgeschrittenerem Stadium der Erkrankung entnommen und verglichen. In beiden Fällen zeigten bereits die frühen Biopsien ein völliges Fehlen der großkalibrigen, dickbemarkten Axone. Ebenfalls als frühe Veränderung wurde eine Erweiterung des endoneuralen Interstitiums festgestellt. Eine geringe Anzahl der vorhandenen bemarkten und unbemarkten Axone in allen Biopsien wies degenerative Veränderungen auf. Die für die progressive neurale Muskelatrophie typische Zwiebelschalenbildung der Schwannschen Zellen — möglicherweise eine Reaktion auf wiederholte De-und Remyelinisierungsvorgänge um dystrophische Axone — trat erst in den späteren Biopsien deutlicher hervor. Hinsichtlich der formalen Genese der hypertrophischen Neuropathie bei neuraler Muskelatrophie sind nach diesen Beobachtungen axonale Dystrophie und interstitielle Veränderungen des Endoneuriums als primäre Entmarkung und Zwiebelschalenbildung als sekundäre Phänomene zu betrachten. Die Möglichkeit einer kausalen Beziehung zwischen axonaler Dystrophie und interstitiellen Veränderungen wird an Hand der vorliegenden Befunde und Literatur diskutiert.
    Notes: Summary Serial nerve biopsies were performed at an early, and at an advanced stage of the disease in 2 patients with progressive neural muscular atrophy. The early biopsy showed a complete loss of the large diameter and thickly myelinated fibres, as well as an expansion of the endoneurial interstitium in both cases. Myelinated and unmyelinated fibres exhibited axonal degeneration in all biopsies occasionally. “Onion bulb” formation, a typical feature of peripheral neuropathy in neural muscular atrophy, was found to be prominent only in the latter biopsies. As regards the formal pathogenesis of hypertrophic neuropathy in neural muscular atrophy, axonal dystrophy and interstitial changes of the endoneurium were regarded as primary phenomena, demyelination and “onion bulb” formation as secondary. A possible causal relation between axonal dystrophy and interstitial changes, observed in these cases, is discussed in the light of the present literature.
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    URL: http://dx.doi.org/10.1007/BF00313355
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    Purification, some properties and quaternary structure of thed-ribulose 1,5-diphosphate carboxylase ofAlcaligenes eutrophus (1976)
    Springer
    Archives of microbiology 110 (1976), S. 157-166 
    Details
    ISSN: 1432-072X
    Keywords: d-Ribulose 1,5-diphosphate carboxylase ; Oxygenase activity ; Quaternary structure ; Electron microscopy ; Alcaligenes eutrophus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract d-Ribulose 1,5-diphosphate carboxylase has been purified from autotrophically grown cells of the facultative chemolithotrophic hydrogen bacteriumAlcaligenes eutrophus. The enzyme was homogeneous by the criteria of polyacrylamide gel electrophoresis. The molecular weight of the enzyme was 505000 determined by gel filtration and sucrose density gradient centrifugation, and a sedimentation coefficient of 18.2 S was obtained. It was demonstrated by sodium dodecyl sulphate-polyacrylamide gel electrophoresis that the enzyme consists of two types of subunits of molecular weight 52000 and 13000. Electron microscopy on the intact and the partially dissociated enzyme lead to the construction of a model for the quaternary structure of the enzyme which is composed of 8 large and 8 small subunits. The most probable symmetry of the enzyme molecule is 4:2:2. Michaelis constant (K m ) values for ribulose 1,5-diphosphate, Mg2-, and CO2 were 0.59 mM, 0.33 mM, and 0.066 mM measured under air. Oxygen was a competitive inhibitor with respect to CO2 suggesting that the enzyme also exhibits an oxygenase activity. The oxygenolytic cleavage of ribulose 1,5-diphosphate was shown and a 1:1 stoichiometry between oxygen consumption and 3-phosphoglycerate formation observed.
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    URL: http://dx.doi.org/10.1007/BF00690223
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  • 88
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    Physiology and fine structure of sporangiospore germination in Piptocephalis unispora prior to infection (1976)
    Springer
    Archives of microbiology 107 (1976), S. 99-107 
    Details
    ISSN: 1432-072X
    Keywords: Piptocephalis unispora ; Mucorales ; Kickxellaceae ; Electron microscopy ; Germination ; Spore swelling ; Sporangiospore
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Germination of the sporangiospore of Piptocephalis unispora Benjamin, observed by means of light and electron microscopy, involved the formation of a new inner wall which became continous with the inner layer of the wall of the germ tube. The outer wall layer of the germ tube was continous with the original inner wall layer of the dormant spore. Preliminary details of appressorium structure were noted. Nutritional experiments indicated that sporangiospores required external sources of utilisable nitrogen and carbon compounds for maximal swelling and germ tube production. Limited development occurred when either nutrient was supplied singly. Comparison of germination of the asexual spore with that in other Mucorales, especially the Kickxellaceae, has been made, and the merosporangial status in P. unispora discussed.
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    URL: http://dx.doi.org/10.1007/BF00427874
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  • 89
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    Microfilament bundles in antheridial nuclei of Achlya ambisexualis E 87 (1976)
    Springer
    Archives of microbiology 107 (1976), S. 113-114 
    Details
    ISSN: 1432-072X
    Keywords: Achlya ; Electron microscopy ; Nuclear microfilaments ; Antheridia ; Mycology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This is the first report of intranuclear microfilaments within gametangial nuclei of oömycetous fungi. Longitudinal sections of four to six microfilaments were frequently observed in meiotic antheridial nuclei of Achlya ambisexualis. Each microfilament measured approximately 7–10 nm in diameter. Spindle tubules (25 nm in diameter) were also observed within some of the nuclei possessing microfilaments.
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    URL: http://dx.doi.org/10.1007/BF00427876
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  • 90
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    Electron microscopy of isolated cell walls of Bacillus subtilis var. niger (1976)
    Springer
    Archives of microbiology 109 (1976), S. 195-197 
    Details
    ISSN: 1432-072X
    Keywords: Cell wall ; Peptidoglycan ; Electron microscopy ; Bacillus subtilis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Isolated cell walls of Bacillus subtilis have a striated appearance in the electron microscope. The structure persists when teichoic acids are removed. It is inferred that the structure bears on the arrangement of the peptidoglycan chains.
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    URL: http://dx.doi.org/10.1007/BF00425135
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  • 91
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    Penetration of Phytophthora cinnamomi into disease tolerant and susceptible eucalypts (1976)
    Springer
    Archives of microbiology 108 (1976), S. 231-242 
    Details
    ISSN: 1432-072X
    Keywords: Phytophthora ; Penetration ; Eucalypts ; Roots ; Electron microscopy ; Appressoria ; Plugs
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The mechanisms of penetration of Phytophthora cinnamomi Rands into seedling eucalypt roots were studied by light and electron microscopy. Culture grown seedlings of root-rot tolerant Eucalyptus st johnii and root-rot susceptible Eucalyptus obliqua were inoculated with both zoospores and mycelium. Zoospores encysted on roots of both species and the germ tubes penetrated without the formation of appressoria. Swellings, previously described as appressoria, were formed when the germ tube was slow to enter the host by intracellular penetration. Vegetative hyphae penetrated both inter- and intracellularly into the zones of root elongation and differentiation, often through root hairs. Evidence of hydrolysis of the host cell-wall at the point of penetration was observed in electron micrographs. Several hours after the germ tube penetrated the epidermis, a thick plug of amorphous material formed in the germ tube slightly below the level of the outer walls of the epidermal cells, sealing off the hypha within the root. Behaviour of zoospores and germ tubes and the mechanism of penetration were similar on both hosts. Micrographs do not suggest any kind of a hypersensitive reaction by the host cells during the early stages of infection.
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    URL: http://dx.doi.org/10.1007/BF00454847
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  • 92
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    The fine structure of Micrococcus radiophilus and Micrococcus radioproteolyticus (1976)
    Springer
    Archives of microbiology 107 (1976), S. 313-320 
    Details
    ISSN: 1432-072X
    Keywords: Micrococcus radiophilus ; Micrococcus radioproteolyticus ; Bacterial cell walls ; Fine structure ; Electron microscopy ; Taxonomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The radiation resistant bacteria Micrococcus radiophilus and M. radioproteolyticus were studied by thin sectioning and freeze-etching techniques and the two species were found to be similar in the fine structure. The only significant difference was in the appearance of the surfaces of the cell walls in freeze-etched preparations. Since the two species, together with M. radiodurans, possess a unique cell wall structure and a cell wall peptidoglycan, which is different from that of other micrococci and Gram-positive cocci, it is recommended that they be reclassified into a new genus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00425346
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  • 93
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    Alterations in the cell wall of Spirillum serpens VHL early in its association with Bdellovibrio bacteriovorus 109D (1976)
    Springer
    Archives of microbiology 108 (1976), S. 55-64 
    Details
    ISSN: 1432-072X
    Keywords: Bdellovibrio ; Spirillum ; Cell wall ; Bdelloplast ; Lipoprotein ; Peptidoglycan ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In both freeze-etched and critical-point dried preparations examined by transmission and scanning electron microscopy, respectively, the outer surfaces of the cells of Spirillum serpens VHL assume a wrinkled appearance 10–15 min after challenge by Bdellovibrion bacteriovorus 109D. This wrinkling effect is believed (on circumstantial evidence) to be caused by the bdellovibrio's disruption of the cell wall lipoprotein of the Spirillum. With the exception of those topological changes caused by wrinkling, the outer membrane of the Spirillum cell wall retains a normal appearance as viewed in freeze-etched preparations, even after the Spirillum cell has been converted into a bdelloplast. Although the peptidoglycan layer of the Spirillum cell presumably is weakened somewhat by the invading Bdellovibrio, evidence obtained from freeze-fractured preparations of Spirillum bdelloplasts suggests that the peptidoglycan remains as a discrete cell wall layer, even though the Spirillum cell wall apparently has lost much of its rigidity. That the peptidoglycan backbone remains essentially intact, even after the Spirillum cell has been entered by the Bdellovibrio, is supported by the observation that the soluble amino sugar content of the culture medium, as determined by chemical analysis, does not rise even 5.0 h after the association of the Bdellovibrio with the Spirillum has begun.
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    URL: http://dx.doi.org/10.1007/BF00425093
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    The cytology of the gametes and fertilization of Allomyces macrogynus (1976)
    Springer
    Archives of microbiology 109 (1976), S. 21-30 
    Details
    ISSN: 1432-072X
    Keywords: Electron microscopy ; Allomyces ; Gametes ; Fertilization ; Membrane fusion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The gametes and the process of fertilization were examined by light and electron microscopy in the lower eukaryote Allomyces macrogynus. Differences in gamete morphology included the overall larger size and the presence of a larger nuclear apparatus, along with the association of a side-body complex and many more mitochondria in the female gamete. In this species of Allomyces, fertilization was initiated by contact and fusion of specialized regions of the gamete plasma membranes resulting in a binucleate fusion cell surrounded by plasma membrane contributed by both partners. Following plasmogamy, nuclear fusion was initiated by multiple nuclear membrane contacts between adjacent outer membranes. Following inner membrane fusion, small nucleoplasmic bridges were observed which presumably fused with one another and resulted in a single bridge which widened, forming the mature diploid nucleus. After karyogamy, fusion of the nuclear caps did not always occur and zygotes with and without fused caps were observed. Coalescence of the nucleoli completed the events of fertilization, forming a zygote with a single nuclear apparatus (sometimes with two caps) and two flagella. These observations are discussed in relation to fertilization mechanisms and compared to fertilization in other organisms.
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    URL: http://dx.doi.org/10.1007/BF00425108
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  • 95
    Electronic Resource
    Electronic Resource
    Structure and composition of intracytoplasmic membranes of Ectothiorhodospira mobilis (1976)
    Springer
    Archives of microbiology 107 (1976), S. 167-182 
    Details
    ISSN: 1432-072X
    Keywords: Ectothiorhodospira mobilis ; Photosynthetic membranes ; Electron microscopy ; Isolation of membranes ; Structure of membranes ; Composition of membranes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The lamellar membrane stacks of Ectothiorhodospira mobilis were isolated and purified by a combination of lysozyme and osmotic shock treatment, followed by differential and density gradient centrifugation. Preparations of lamellar membranes were enriched at least 2.4-fold in the ratio of bacteriochlorophyll a to protein. Thin-sectioning, negative staining, platinumcarbon shadowing and freeze-etching were used to study the architecture of the membrane units. Both platinum-carbon shadowing and freeze-etching showed the outer surfaces of the isolated lamellar membrane stacks to be relatively smooth. Particles averaging 7 nm in diameter were seen on several faces following freeze-ctching. Non-polar amino acids amounted to 60% of the total amino acid composition. Lipids constituted 32% of the membrane dry weight. Phosphatidyl ethanolamine and diphosphatidyl glycerol were the major phospholipids. Fatty acids of 10–15 carbons represented a small fraction of both membrane and whole cell fatty acids. Monoenes constituted 36% of the total membrane fatty acids and 38.4% of the total whole cell fatty acids. The major fatty acids of both whole cells and purified membranes were C16:0, C18:1 and cyclopropane C19:0.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00446836
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  • 96
    Electronic Resource
    Electronic Resource
    Intracelluläre Organisation phagenschwanz-ähnlicher Bacteriocine der Gruppe A in Serratia marcescens (1976)
    Springer
    Archives of microbiology 111 (1976), S. 175-183 
    Details
    ISSN: 1432-072X
    Keywords: Serratia marcescens ; (Phage tail) bacteriocin ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung Die Genese eines phagenschwanzähnlichen Bacteriocins in Zellen des Gruppe A-bacteriocinogenen (bA+) Serratia marcescens-Stammer Nr. 16 wurde nach Mitomycin C (MC) Induktion elektronenoptisch untersucht. Dieses Bacteriocin (Gesamtlänge 117 nm) besteht aus einem hohlen Stift mit kontraktiler Scheide. Nach 60 min Induktion wurden in Dünnschnitten stäbchenförmige Bacteriocine identifiziert. Sie erscheinen in drei Aggregationsformen: 1. als hexagonale Einschlüsse, 2. als Bänder dicht nebeneinanderliegender Bacteriocine und 3. als Stapel von übereinanderliegenden Bacteriocinschichten, wenn nach 120 min Induktion ein Maximum von ca. 450 Bacteriocinen pro Zelle erreicht wird. Bacteriocine konnten nach der gleichen Induktionszeit von 60 min auch mit der “in situ lysis technique” nachgewiesen werden. Neben Bacteriocinen traten relativ selten und unregelmäßig auch Phagenköpfe auf. Die Stäbchenform teilungsfähiger Zellen blieb bis zum Auftreten von intracellulären Bacteriocinen erhalten. Ihre Umwandlung in geblähte, sphäroplastenähnliche Zellformen, die nach 120 min Induktion lysierten, war zeitlich korreliert mit Feinstrukturveränderungen der Zellwand.
    Notes: Abstract The biosynthesis of a phage tail-like Bacteriocin by cells of the group A-bacteriocinogenic (bA+ Serratia marcescens strain no. 16 after induction with mitomycin C (MC) was examined electronmicroscopically. This bacteriocin (total length 117 nm) consists of a hollow core and a contractile sheath. At 60 min following induction, rod-like bacteriocin-partieles were identifiable in ultrathin sections. The particles were found to comprise three morphologically different forms of aggregation: 1. hexagonal inclusions, 2. contiguous, bank-like particles, and 3. staples of superimposed layers of bacteriocin particles. At 120 min after induction bA+ cells revealed maximally 450 bacteriocin particles. Similarly, the phage tail particles could be demonstrated with the “in situ lysis technique” at 60 min following induction. Occasionally, phage heads were demonstrable, but in no instance were complete phage particles discernible. Dividing cells of the bA+ strain of S. marcescens maintained their rod-form following induction with MC until intracellular phage tail bacteriocin particles were seen. However, at 120 min after induction, the swollen, sphaeroplast-like cells lysed, an event that could be correlated with fine structural alterations of the cell wall.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00446566
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  • 97
    Electronic Resource
    Electronic Resource
    Specificity of innervation of iris musculature by sympathetic nerve fibres in tissue culture (1976)
    Springer
    Pflügers Archiv 361 (1976), S. 127-134 
    Details
    ISSN: 1432-2013
    Keywords: Tissue culture ; Fluorescence histochemistry ; Electrophysiology ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Irides from 3–5 day old rats have been grown 1–3 mm from superior cervical or lumbar paravertebral sympathetic ganglia in modified Rose chambers. The two muscles of the iris received distinctly different innervation patternsin vitro, and these were similar to those seenin vivo. Varicose, adrenergic fibres were consistently associated with the dilator pupillae rather than with the sphincter pupillae while excitatory, cholinergic junctions developed between the nerve fibres and the muscle cells of the sphincter but not the dilator. There was a lack of specificity shown by the sympathetic neurons during this innervation. Fibres from lumbar ganglia formed plexuses within the dilator similar to those formed by superior cervical fibres, and sympathetic, cholinergic fibres were able to substitute for the normal parasympathetic, cholinergic fibres in the sphincter.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00583456
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  • 98
    Electronic Resource
    Electronic Resource
    Cellular differentiations and structural characteristics in nasopharyngeal angiofibromas (1976)
    Springer
    Virchows Archiv 371 (1976), S. 273-282 
    Details
    ISSN: 1432-2307
    Keywords: Nasopharyngeal angiofibroma ; Fibroblast ; Vascular cells ; Fibromatosis ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary An electron-microscopic study of 9 nasopharyngeal angiofibromas was performed in order to elucidate the ultrastructural characteristics. Stromal fibroblasts and proliferating cells of the microvasculature were found. The stromal fibroblasts were subdivided into 3 different groups: (1) “classical” fibroblasts, (2) fibroblasts with histiocytelike features, and (3) fibroblasts with myoid features. By proliferation the cells of the capillary vessels change into stromal cells. A particular pattern of nuclei and dense intranuclear granules is only found in stromal fibroblasts. Consequently fibroblasts as well as cells of the microvasculature contribute to the pool of tumor cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00433074
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  • 99
    Electronic Resource
    Electronic Resource
    Fluorescence histochemical and electron-microscopical observations on the innervation of the atrial myocardium of the adult human heart (1976)
    Springer
    Virchows Archiv 371 (1976), S. 101-119 
    Details
    ISSN: 1432-2307
    Keywords: Human heart ; Innervation ; Fluorescence histochemistry ; Electron microscopy ; Catecholamines
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The existence of both adrenergic and cholinergic innervation of the atrial myocardium of the adult human heart was demonstrated by means of fluorescence induced by formaldehyde or glyoxylic acid and by electron microscopy. The adrenergic fluorescing axons (1) followed the course of blood vessels as typical perivascular nerve plexuses, and (2) formed a three-dimensional fairly dense nerve net obviously not related to the blood vessels. The varicosities frequently came into close apposition on myocardial cells. Several types of nerve terminals were differentiated at electron microscopy: (1) an “adrenergic” type containing small (diameter 450–700 Å) dense-cored vesicles and usually (in various proportions) small “empty” and/or large (900–1500 Å) dense-cored vesicles, (2) a “cholinergic” type containing small (ca. 500 Å) “empty” vesicles and occasionally also some large (mean diameter ca. 1200 Å) dense-cored vesicles, (3) a “pale” type containing only a few or no vesicles, (4) a “disintegrated” type containing degenerated mitochondria, autophagic vacuoles, and occasional normal-looking mitochondria, (5) nerve terminals containing a large number of mitochondria in addition to varying vesicle populations, and (6) a (possibly baroreceptive type of) nerve terminal containing myelinlike lamellated structures. The “disintegrated” and the “pale” types of nerve terminals possibly represent different stages of axonal degeneration, or may correspond to diminution in the transmitter substance concentration under certain pathophysiologic conditions, respectively. Nerve terminals crowded with mitochondria may be sensory and involved in mechano-or chemoreceptive functions. In preliminary experiments convincing evidence was obtained that the glyoxylic acid-induced fluorescence histochemical method will be suitable for comparative studies on (human) clinical specimens, e.g., for analyzing the degree of the functional activity of the intrinsic adrenergic innervation of the myocardium under various pathophysiologic conditions. The modification which appeared most appropriate for such studies is described in detail, and is proposed for use as a standard method in other similar or related studies on human clinical series. The essential criteria for analyzing the specimens at fluorescence microscopy are suggested as well.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00444927
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  • 100
    Electronic Resource
    Electronic Resource
    Fine structure of baroreceptor terminals in the carotid sinus of guinea pigs and mice (1976)
    Springer
    Cell & tissue research 170 (1976), S. 95-112 
    Details
    ISSN: 1432-0878
    Keywords: Baroreceptors ; Carotid sinus ; Mechanoreceptors ; Electron microscopy ; Fluorescence histochemistry ; Guinea pig, mouse
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary A light and electron microscopic study was undertaken on the baroreceptor axon terminals in the carotid sinus of guinea pigs and mice, using serial semithin and thin sections. Together with their enveloping Schwann cells, numerous lanceolate axon terminals are organized into a well-defined discoid end organ, referred to as the ‘baroreceptor unit’. Baroreceptor units measure 100 to 150 μm in diameter and are arranged in a hexagonal pattern. These end organs represent free branched lanceolate mechanoreceptors of complex type (Andres and von Düring, 1973) which belong to the main group of stretch receptors. In the guinea pig the lanceolate terminals enter the media and approach the innermost layers near the intima. In the mouse the terminals are seen to spread in the adventitia and along the medio-adventitial border. Only a few of them penetrate the external elastic layer. Species differences concerning the localization and extent of these visceral mechanoreceptors are discussed, as well as the modified architecture of the sinus wall in the receptor area (‘elastic segment’). Lanceolate terminals form beaded varicosities which are equipped with finger-like or lamellar axoplasmic protrusions. These projections contain a well-differentiated receptor matrix. They are attached to collagen and elastic fibers. The varicosities include densely packed mitochondria, neurotubules, profiles of axoplasmic reticulum, clear and granular vesicles, and striking accumulations of glycogen particles, lamellated bodies and lysosomes. Four types of varicosities are discerned according to their main axoplasmic components. Various types of these varicosities occur within an individual lanceolate terminal. The adrenergic innervation of the carotid sinus was studied by fluorescence histochemistry. In guinea pigs a multilayered wide-meshed plexus of fluorescent fibers occurs in the adventitia where it is closely related to baroreceptor stem fibers. However, adrenergic axons do not enter the media. In mice fluorescent fibers are extremely rare in the adventitia of the carotid sinus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00220113
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