Fig. 5. White matter astrocyte formation deficiency in the Olig2 mutant spinal cord. In situ hybridization and immunostaining of Olig2, GFAP, S100ß and GS were performed on frozen spinal sections of Ctrl^G and Cko^G mice at P14. Arrows indicate the white matter region of the spinal cord. (A,B) mRNA expression of Gfap was examined in the control (A) and Olig2 (B) mutant spinal cord by in situ hybridization. (C-F) Expression of Olig2 and GFAP was analyzed by immunohistochemistry in the control (C) and Olig2 mutant (E) spinal cord. GFAP expression in C,E is shown in D,F, respectively. GFAP is strongly expressed in the spinal white matter of the control, but only weakly in the mutant (arrows). (G-N) Expression of Olig2 and S100ß (G,I), and Olig2 and GS (K,M), were analyzed by immunohistochemistry in the spinal cord of control (G,H,K,L) and Olig2 mutant (I,J,M,N) mice. Staining of S100ß and GS is shown in H,J and L,N, respectively. S100ß- and GS-expressing cells are barely detectible in the white matter of Olig2 mutants (J,N) as compared with controls (H,L). (O) Bar chart showing the average number of S100ß⁺ and GS⁺ cells per unit area (0.06 mm²) in the spinal white matter of control and Olig2 mutant mice (n=3); bars indicate s.d. Scale bar: 100 µm in A-N.