Fig. 4. Effects of neonatal Olig2 ablation on white matter astrocyte development. (A-D) Cre and GFAP expression in the cerebral white matter (A,B) and SVZ (C,D) of hGFAP-Cre mice at P14 was examined by immunohistochemistry. Arrowheads indicate Cre⁺ cells (B,D) and Cre⁺ GFAP⁺ cells (A,C). LV, lateral ventricle; wm, white matter. (E-L) Control (Olig2C/+;CAGGS^CreErTM) and Olig2Cko;CAGGS^CreErTM pups were administrated with tamoxifen (TM) for 4 days from P2 to P5, and their brains were harvested at P13. Expression of Olig2 (E,F), Mbp (G,H) and Gfap (I,J) was examined by in situ hybridization on coronal sections of the cortex. Boxed areas in I,J are shown at high magnification in K,L, respectively. Arrows and arrowheads indicate the white matter and the SVZ, respectively. (M) Bar chart showing the average number per unit area (0.1 mm²) of GS⁺ cells in the cortex (Ctx) and the white matter (Wm) and CC1⁺ cells in the white matter of TM-treated control (Olig2C/+;CAGGS^CreErTM) and Olig2Cko;CAGGS^CreErTM animals (n=3); bars indicate s.d. Scale bars: 100 µm in A for A,B, and C for C,D.