Genesis of Neuroepithelial Cells in The Adult CNS
In the adult CNS, neuroepithelial cells arise in several different areas of the brain: the subventricular zone (SVZ), the olfactory bulb and the dentate gyrus of the hippocampus. These cells do not appear in any of the peripheral nervous system. Often categorized as neural stem cells, neuroepithelial cells give rise to only a few varieties of neural cells, making them multipotent - a definite distinction from the pluripotent stem cells found in embryonic development. Neuroepithelial cells undergo mitosis generating more neuroepithelial cells, radial glial cells or progenitor cells, the latter two differentiating into either neurons or glial cells. The neuroepithelial cells undergo two different forms of mitosis: asymmetric differentiating division and symmetric prolific division. The asymmetric cell division results in two different varieties of daughter cells (i.e. a neuroepithelial cell divides into a radial glial cell and another neuroepithelial cell), while the symmetric version yields identical daughter cells. This effect is caused by the orientation of the mitotic spindle, which is located in either the posterior or anterior area of the mitotic cell, rather than the center where it is found during symmetric dividion. The progenitor cells and radial glial cells respond to extracellular trophic factors - like ciliary neurotrophic factor (CNTF), cytokines or neuregulin 1 (NGR1) - that can determine whether the cells will differentiate into either neurons or glia. On a whole, neurogenesis is regulated both by many varied regulatory pathways in the CNS as well as several other factors, from genes to external stimuli such as the individual behavior of a person. The large interconnected web of regulatory responses acts to fine-tune the responses provided by newly formed neurons.
Read more about this topic: Neuroepithelial Cell, Adult Neurogenesis
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