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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 71 (1986), S. 136-141 
    ISSN: 1432-0533
    Keywords: Ependymoblastoma ; Brain neoplasm ultrastructure ; Ependymoma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The ependymoblastoma is a rare, primitive neuroectodermal tumor morphologically distinct from the ependymoma and the malignant or anaplastic ependymoma. This neoplasm is characterized by uniform neuroepithelial cells, ependymoblastic rosettes, perivascular pseudorosettes and numerous mitotic figures. The fine structure of this neoplasm is characterized by a predominant population of well-differentiated ependymal cells and intermingling mitotic figures. Many cells have an apical surface bearing cilia and microvilli projecting into a lumen and interconnected to adjacent cells by zonulae adhaerentes. The basal surface often forms a basal lamina-lined labyrinth. This tumor also contains a population of cells less differentiated than 3-week embryonal ependymal cells. Intermediate cell forms suggesting multiple lines of differentiation occurring within a single cell are not present in this human ependymoblastoma. The ependymoblast represents a stage in the differentiation of the primitive medulloepithelial cell to the mature ependymocyte.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 73 (1987), S. 153-159 
    ISSN: 1432-0533
    Keywords: Cerebral neuroblastoma ; Polar spongioblastoma ; Palisading ; CNS neoplasm
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The present case study portrays a neoplasm composed predominantly of palisading uni-and bipolar cells with histological features mimicking the polar spongioblastoma. Ultrastructural examination of this single case reveals cells that range from the embryonal neuroepithelial cell to neurons with synapse formation and the presence of dense-cored vesicles in neurites. The morphology of these neoplastic cells is similar to the neuronal line of differentiation described in both normal developing mammalian central nervous system and in the transplantable mouse teratoma line (OTT-6050). Glial differentiation is not present in the areas of palisading. We would like to emphasize that the diagnostic pattern characteristic of the polar spongioblastoma may be found in tumors of neuronal origin, although most polar spongioblastomas having the typical pattern of palisading seem to belong to the astrocytic cell line.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-0533
    Keywords: Recombinant retrovirus ; Schwann cells ; β-Galactosidase ; Demyelination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary This series of experiments is designed to follow the fate of implanted Schwann cells by first labeling them with a recombinant retrovirus encoding the bacterial β-galactosidase gene, then injecting them into the spinal cord after a demyclinating lesion has been produced. The label provides a means of distinguishing the exogenous Schwann cells from endogenous ones and of determining their travel pattern and myelinating or ensheathing behavior in the central nervous system (CNS). Neonatal rat primary Schwann cells were stimulated to divide by administering glial growth factor and forskolin. Fresh virus-containing supernatant from Psi2 cells producing retrovirus LZ1 was placed in cell culture to label the cells. The capacity of infected Schwann cells to form myelin was verified by coculturing in vitro with neurons from embryonic dorsal root ganglia. Infected cells were injected into the right side of adult syngenic rat spinal cords after a lysolecithin-induced demyelinating lesion had been produced 1 cm caudal on the left side. After 3 weeks the animals were killed, perfused for electron microscopy, and spinal cord sections histochemically stained for β-galactosidase activity using the chromogenic substrate 5-bromo-4-chloro-3-indoyl-β-d-galactosidase (X-Gal) which forms a blue precipitate in infected cells. The labeled cells, easily recognized macro-and microscopically, were clustered at the cell injection site, in the dorsal meninges and, at the area of demyelination, bilaterally in the superficial aspect of the dorsal funiculi. Labeled cells were not evident in the neuropil midway between the injection and demyelination sites. In the electron microscope, the cells containing the electron-dense precipitate from the hydrolysis of X-Gal were identified at the lesion site and some of these cells ensheathed axons. These data suggest that implanted Schwann cells migrate to a demyelinating lesion in the subarachnoid space rather than through the parenchyma.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Journal of neurocytology 17 (1988), S. 521-529 
    ISSN: 1573-7381
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We have recently reported the immortalization of primary Schwann cells isolated from sciatic nerves of normal neonatal rats. The cells were maintained under continuous mitogenic stimulation with glial growth factor and forskolin, achieving immortalization after 12 to 15 weeks without the use of viral infection, oncogene transformation or chemical carcinogens. The immortalized cells (1.17 cells) initially retain the capability to recognize and attach to peripheral neurons in culture as well as the ability to myelinate those neurons. The functional capacity of the cells gradually diminishes in culture, such that late passage cells can ensheath neurons but cannot form a myelin sheath. Both normal and immortalized cells secrete comparable amounts of autocrine growth factor activity in culture that can be regulated by extracellular matrix proteins. The difference between quiescent and immortalized Schwann cells seems to lie not in the production of growth factor but rather in the relative ability to respond to the factor(s). To test the potential of the immortalized Schwann cells for the ability to form tumoursin vivo, we injected equal numbers of primary or immortalized Schwann cells into the sciatic nerve of adult syngenic rats and allowed them to incubate there for 6 to 13 weeks, whereupon the injected nerves were inspected for tumour formation. In every case (N=3) the primary cells had no effect whereas every injection of immortalized cells (N=5) resulted in a solid cellular mass surrounding the injected nerve. The tumours were encapsulated masses of actively dividing Schwann-like cells that surrounded but did not invade the nerve fascicle. The cells in the tumour expressed the Schwann cell surface antigens laminin, 217C (Ran 1) and S-100 like the immortalized cells that had been injected. Within the tumour the cells were embedded in a collagenous matrix, were surrounded by basal lamina and occasionally attained an orientation comparable to the Antoni A or Antoni B patterns typical of human schwannomas. These data suggest that rat Schwann cells immortalizedin vitro by chronic mitogenic stimulation can provide an experimental animal model for human schwannomas and neurofibromas.
    Type of Medium: Electronic Resource
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