Figure 4.

Production of astrocytes in the mammalian brain. (A) Two proposed models for the generation of astrocytes from radial glial progenitors (RGCs) in the developing cerebral cortex (boxed area). (B) Proposed stepwise differentiation of astrocytes from NSCs. The features and representative expressed/regulatory genes of RGCs, astrocyte precursors (APs), and astrocytes are schematically shown. Like NBs and OPCs in the neuronal and oligodendrocyte lineages, the occurrence of an intermediate proliferative precursor cell type [astrocyte precursor (AP)] is speculated in the astrocyte lineage, but their exact identity is currently unknown. For details, see text. Abbreviations: MZ, mantle zone. Others are same as in Figure 1.