Fig. 7. Altered expression of Krox20 and Epha4 in Msx1/2 mutant hindbrain. Whole-mount in situ hybridization analysis of E8.5 and E9.5 embryos with the indicated probes. (A-F) Expression of Krox20 at E8.5 (A-D) and E9.5 (E,F). The box in A and B demarcates the region shown in C and D. Note the reduction in the level of Krox20 transcripts in the caudal portion of r5 in mutant embryo at E8.5 (B,D), but normal expression at E9.5 (F). (G-L) Expression patterns of Hoxb1 in r4 (G,H), Hoxd4 in the region caudal to r7 (I,J), and Crabp1 from r2 to r6 (K,L) at E9.5 show no apparent change in the mutant hindbrain. (M-P) Epha4 expression at E9.5. Enlarged view of rectangles in M and N is shown in O and P. Epha4 expression was significantly increased in r1, r2 and r3 of the Msx1/2 mutant (arrowheads in P). Scale bars: in B (for A,B), F (for E,F), H (for G,H), J (for I,J), L (for K,L), 0.2 mm; D (for C,D), 0.1 mm.