Fig. 4. Math1 was necessary for Mbh1 expression in the spinal cord. Transverse sections at brachial (A-C,E-G) and forebrain levels (D,H) of E11.5 Math1^+/+ (A-D) and Math1^–/– (E-H) mouse embryos were hybridized with antisense cRNA probes for Math1 (A,E), Mbh1 (B,D,F,H) and Lhx9 (C,G). Loss of Mbh1 and Lhx9 expression was observed through all axial levels of the spinal cord in all Math1^–/–embryos (n=3). Scale bar: 100 µm.