Fig. 4. Effect of the Mash1 mutation on the generation of dILA neurons. Dorsal neurons in control, Mash1^–/– and Mash1^Ngn2/Mash1^Ngn2 embryos were analyzed at E12.5 using immunohistochemistry, with antibodies directed against (A-F) Lhx1/5 (green) and Tlx3 (red), (H-J) Pax2 (green) and Lmx1b (red). dILA neurons express Lhx1/5 and Pax2, and dILB neurons express Tlx3 and Lmx1b. (G,K) Numbers of BrdU+ dILA (dark-grey columns) and BrdU+ dILB (light grey columns) neurons in control (c), Mash1^–/– (^–/–) and Mash1^Ngn2/Mash1^Ngn2 (N2/N2) mutant mice, as assessed 24 hours after BrdU injection. The number of dILA neurons is reduced in Mash1^–/– embryos. (L-N) Analysis of Ptf1a (green) and Mash1 (red) expression in the dorsal spinal cord of control (L), Mash1^–/– (M) and Mash1^Ngn2/Mash1^Ngn2 (N) embryos. (O) Numbers of Ptf1a+ cells (black columns) in control (c), Mash1^–/– (^–/–) and Mash1^Ngn2/Mash1^Ngn2 (N2/N2) mutant mice. The error bars represent the standard deviation. (P-R) In situ hybridization of sections from E12.5 control, Mash1^–/– and Mash1^Ngn2/Mash1^Ngn2 spinal cords using a probe directed against Hes5 mRNA. Scale bars: 100 µm in A-C,P-R; 50 µm in D-F,H-J,L-N.