Fig. 2.

NG2 cell-derived astrocytes in the dorsal forebrain of P21 Olig2 Cko and Ctr mice. (A-D) EGFP fluorescence (green, A,B) and NG2 immunolabeling (red, C and D) of the neocortex of P21 Olig2 Cko (A,C) and Ctr (B,D) mice. Upper left is pial surface. NG2⁺ EGFP⁺ polydendrocytes in the Ctr cortex are completely replaced by NG2-negative EGFP⁺ protoplasmic astrocytes in Cko brain, where NG2 immunoreactivity is detected only in the vasculature (C). (E) Coronal section through P21 Cko neocortex stained for Aldh1L1 (red) and NG2 (blue). EGFP⁺ NG2 cell-derived protoplasmic astrocytes are Aldh1L1⁺. (F,G) EGFP fluorescence (green) and immunolabeling for Aldh1L1 (red) and Ki-67 (blue) in the neocortex of Cko (F) and Ctr (G) mice at P4. In Cko neocortex, Ki-67 is detected mostly in EGFP⁺ cells (arrows in F) but rarely in EGFP^– Aldh1L1⁺ cells, and some EGFP⁺ cells express Aldh1L1 (asterisk in F). In Ctr mice, many EGFP^– Aldh1L1⁺ resident astrocytes are Ki-67⁺ (arrowheads in G). Occasional EGFP⁺ Ki-67⁺ cells are seen in Ctr (arrow in G). Scale bars: 20 μm.