Fig. 5. Deficiency in oligodendrogenesis in Mash1 and Ngn2 mutants. (Aa-De) Early generation of OLPs in various mutant mice at E12.5. Arrowheads indicate marker-positive cells. Insets show higher magnification views of the p^* domain and adjacent areas. Intense tubular staining in Ad-Dd and Ae-De derived from blood vessels. (E,F) Decrease in the numbers of Olig1⁺ and NG2⁺ cells in Mash1^-/- mice between E12.5 and E16.5 compared with wild type. The number of marker-positive cells per transverse section of the lumbar spinal cord, including both the VZ and MZ, was quantified. Data are mean±s.d. obtained from staining of six to ten sections derived from two to three embryos for each genotype (^*, P<0.01). (G-M) Comparison of the numbers of cells expressing OLP markers in various mutant mice at E12.5 (G-L) and E13.5 (M). In G and H, Olig2⁺ and Nkx2.2⁺ cells only in the MZ were counted, whereas in I-M, both the VZ and MZ were subjected to quantification (indicated in boxes). Percentages are values relative to the wild type. Data are mean±s.d. obtained from staining of eight to ten sections derived from two to three embryos for each genotype. ^*, P<0.01 compared to the wild type; ^$, P<0.05; and ^$$, P<0.01 compared to Mash1^-/- mice. Scale bars: in Dd, 100 µm for Aa-Dd; in De, 50 µm for Ae-De.