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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Neurosurgical review 4 (1981), S. 17-31 
    ISSN: 1437-2320
    Keywords: Astrocytoma ; Oligodendroglioma ; Ultrastructure ; Astrocytom ; Oligodendrogliom ; Ultrastruktur
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung 7 Oligodendrogliome, davon 2 mit uniformem Zell-Typ, 4 mit Zell- oder Gewebs-Unregelmäßigkeit, 1 mit glioblastomatösen Veränderungen wurden elektronenmikroskopisch untersucht. Die Tumorzellen zeigten 2 Haupttypen mit morphologischen Übergängen zwischen beiden auf. Die Hauptformen wurden als Typ 1 (undifferenziert) und 2 (differenziert) definiert, gestützt auf die Anzahl anaplastischer Zellen im jeweiligen Tumor und auf die Beobachtung nicht-neoplastischer Oligodendrocyten nach Mori and Leblond (21). Die meisten Tumorzellen aller Fälle wiesen ähnliche licht- und elektronenmikroskopische Charakteristika auf, einschließlich der Zell-Anordnung und ihrer Tendenz, zytoplasmatische Fortätze zu bilden. Diese Befunde waren auch in den glioblastomähnlichen Tumoren zu erkennen und bestätigen damit deren Oligodendrogliom-Komponente. Außerdem fand man regelmäßig in allen Tumoren eine Zunahme der Größe und Zahl der Mitochondrien, reichlich intrazytoplasmatische Strukturen und Mikrotubuli. Auch Zellen mit zytoplasmatischen Filamenten waren vorhanden, die als reaktive Astrocyten oder als oligodendrogliale Tumorzellen angesehen wurden. Daher scheinen weder zytoplasmatische Filamente noch Mikrotubuli ein spezifisches morphologisches Kriterium für Oligodendroglia oder Astrocyten zu sein. Das Überwiegen einer dieser beiden Strukturen erlaubt jedoch eine zytogenetische Zuordnung. Die zytologischen Charakteristika sind zwar keine spezifischen morphologischen Kriterien; die Feststellung ihrer Anwesenheit gibt jedoch wichtige diagnostische Informationen.
    Notes: Summary Seven Oligodendrogliomas (2 with uniform cell type, 4 with cellular or tissue variability, and 1 with glioblastomatous changes) were examined ultrastructurally. The tumor cells were of two principal types with morphologic transitions between the two main types. The two principal cell types were identified as type 1 (undifferentiated) and type 2 (differentiated) on the basis of the number of anaplastic cells in an individual tumor and on the observations of Mori and Leblond (21) on non-neoplastic oligodendrocytes. Most of the tumor cells in all tumors exhibited similar histologic and ultrastructural characteristics including their arrangement and their tendency to form cytoplasmic processes which sometimes formed short stacks. These features were also recognizable in the glioblastomatous example and confirmed the presence of an oligodendroglial component. In addition to these characteristics, an increase in size and number of mitochondria, abundant intracytoplasmic structures, microtubules were regularly present in virtually all tumor cells. Cells rich in cytoplasmic filaments were present. These were identified as reactive astrocytes or as oligodendroglial tumor cells. Thus neither cytoplasmic filaments nor microtubules appear to be specific morphological markers for oligodendroglia or astrocytes; only the predominance of one of these structures permits cytogenetic identifications. The cytologic characteristics are not specific morphologic markers; however, recognition of their presence provides important diagnostic information.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 59 (1983), S. 309-315 
    ISSN: 1432-0533
    Keywords: Mouse brain ; Oligodendroglia ; Ethylnitrosourea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The aim of this EM study was to assess the relationship of demyelination changes induced in mouse brain by a carcinogenic substance to the early steps in the evolution of neoplastic disease. The investigation on the 25 experimental mice injected at various stages of age with ethylnitrosourea revealed demyelination foci in three animals and interfascicular nests of abnormal cells in seven animals, the latter most probably being of oligodendroglial origin. The nest cells were characterized by their large size and a multitude of interdigitated cytoplasmic processes forming complicated membranous patterns. The abnormal development of oligodendroglial cytoplasmic processes is considered to be the cause of the demyelination. This previously unknown form of oligodendroglial transformation may consist in either the earliest preneoplastic changes or represent a reactive, paraneoplastic type of alteration.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 64 (1984), S. 122-128 
    ISSN: 1432-0533
    Keywords: Hydrocephalus ; Blood-brain barrier ; Tight junctions ; Paracellular pathway ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Considering the possibility of a paracellular route for edema resolution we studied the microvasculature of the subependymal and subcortical white matter in hydrocephalic rats. Normal adult rats were used as controls. After injection of kaolin suspension into the cisterna magna, the animals were killed at intervals of 1, 2, 4, and 8 weeks. In hydrocephalic rats at 1 week after kaolin injection, widening of the interendothelical cleft between the tight junction (dehiscence) was seen in 27 of 76 (35%) vessels. At 2 weeks after kaolin injection, the number of the dehiscences had increased (39/7:56%) and some were enlarged, forming interendothelial blisters. At 4 weeks in hydrocephalic rats, both dehiscences and blisters were still prominent (45/73∶63%) and at 8 weeks the dehiscences were still prominent, but the number of the blisters had decreased (25/81∶31%). The blisters and dehiscences were most pronounced in the corpus callosum and occipital regions. Following i.v. injection of horseradish peroxidase, the interendothelial dehiscences and blisters were completely devoid of the marker substance. These findings indicate that in obstructive hydrocephalus the tight junctions may constitute part of a paracellular pathway for the resorption of interstitial edema fluid.
    Type of Medium: Electronic Resource
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