Fig. 6. Shh signalling converts Gli3, but not Gli2 into a transcriptional activator in somites. E9.5 wild-type (A,E,I,M,Q), Shh^–/– (B,F,J,N,R,V,V'), Gli3^+/–Shh^–/– (C,G,K,O,S), Gli3^–/–Shh^–/– (D,H,L,P,T), Gli2^+/–Shh^–/– (W,W') and Gli2^–/–Shh^–/– (X,X') embryos were analysed by whole-mount in situ hybridisation for myogenin (A-D) and Myf5 (E-X') expression. Transverse sections were performed as indicated by red lines. Black arrows indicate loss of expression. Black arrowheads indicate domains of altered gene expression. Asterisks indicate the ventromedial expansion of Myf5 expression.