Summary
The development of neuroglia has been studied in rat optic nerves with the electron and light microscopes. The main findings of this investigation are as follows:
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1.
Transitional forms between the cell varieties present during development suggest a direct lineage from the neuroectodermal matrix cells lining the lumen of the optic stalk to all neuroglial cell types. There was no evidence of mesenchymal cell invasion, either from the meninges or blood vessels, into optic nerve parenchyma.
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2.
One variety of undifferentiated cells, namely the small glioblasts, may have the potential to either remain in the mitotic cycle giving rise to additional glioblasts, or to differentiate into either astrocytes or oligodendrocytes. Some small glioblasts are retained in fully mature rat optic nerves as a third type of neuroglia and these cells might be a source of the additional oligodendrocytes and/or astrocytes that arise within adult central nervous tissue.
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3.
Astrocytes begin to appear during fetal development. Oligodendrocytes first appear just prior to the time when myelination begins (i.e. 7–9 days postnatal). The early postnatal oligodendrocytes that are forming myelin sheaths are markedly different in appearance from those in mature nerves.
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Aided by a grant from the United Cerebral Palsy Research and Educational Foundation. The author wishes to thank Dr. Alan Peters for his continued interest, support, and critical assistance; and also to express his appreciation to Drs. R. L. Sidman and J. W. Hinds for their criticism of this study. — The technical assistance of Mrs. Patricia L. Hinds and her graphic art work are gratefully acknowledged.
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Vaughn, J.E. An electron microscopic analysis of gliogenesis in rat optic nerves. Z. Zellforsch. 94, 293–324 (1969). https://doi.org/10.1007/BF00319179
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DOI: https://doi.org/10.1007/BF00319179