Figure 1.

General lineage of neural stem cells. Neural stem cells undergo asymmetric division periodically for normal maintenance or in response to injury or other stimuli. One daughter cell (black) is an identical stem cell that renews or repopulates stem cell numbers. The other daughter cell (white) is a more committed progenitor cell that also may divide, one or more times, to create an even greater number of presumptive progeny cells. In the neural system, progeny cells will become postmitotic and mature into the mature central nervous system cell types: neurons, astrocytes, and oligodendrocytes. Reprinted with permission from Elsevier Sciences Ltd from: Weiss S, Reynolds BA, Vescovi AL, et al. Is there a neural stem cell in the mammalian forebrain? Trends Neurosci. 1996;19:387–393.