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| Cell Multiplication | Cell Migration | Growth and Differentiation | Angiogenesis and Metabolism |
|---|---|---|---|
| neurogenesis - formation of neutrons, mitosis of stem cells in the ventricular layer
gliogenesis - formation of glia Cell death - apoptosis |
neuronal migration - radial glia |
Topographical and cytological evolution of the glial phase during prenatal development of the human brain: histochemical and electron microscopic study
J Neuropathol Exp Neurol. 1988 Mar;47(2):166-88.
Kadhim HJ1, Gadisseux JF, Evrard P.
Abstract
An ultrastructural analysis of prenatal gliogenesis and neuronal-glial relationships in the developing fetal brain was carried out using reduced osmium and periodic acid-thiocarbohydrazide-silver proteinate to stain selectively the glycogen content of the glial population. Gliophilic neuronal migration was confirmed in the human fetus, with radial glial fibers (RGF) acting as obligatory corridors for neuronal migration in the prospective neocortex and underlying intermediate zone (IZ). With this method, the entire glial phase was differentiated from neuronal elements; this permitted a description of the evolutionary distribution pattern of RGF: in the cortical plate, glial fascicles fully dissociate by 18 weeks gestation, whereas in the IZ, they remain grouped in fascicles until their transformation into astrocytes. The most conspicuous and constant developmental feature observed in the maturing glial cytoplasm between 21 and 30 weeks gestation was a radical enhancement in the abundance and activity of the lysosomal apparatus and autophagic vacuoles observed in the RGF, a cytological basis for the transformation of radial glial cells into astrocytes. These data have implications for the understanding of the ontogenesis of the neocortical vertical modules in the human brain and for the phylogenetic analysis of the vertical cortical units in terms of comparative mammalian anatomy.
PMID 3339373
- Starting around 21 weeks of gestation, (19 weeks) at the end of neuronal migration, RGCs undergo a transformation into astrocytes and astrocytic precursors. Kadhim HJ, Gadisseux JF, Evrard P. Topographical and cytological evolution of the glial phase during the prenatal development of the human brain: A histochemical and electron microscopic study J Neuropathol Exp Neurol 47:166-188, 1988. PMID: 3339373
