Fig. 3. Myf5 activation is impaired in Gli2^–/–Gli3^–/– embryos. Myf5 expression was analysed by whole-mount in situ hybridisation at E8.5 (A-L) and E9.5 (M-X) in wild-type, Gli2^–/–Gli3^+/–, Gli2^+/–Gli3^–/– and Gli2^–/–Gli3^–/– embryos. Transverse sections were performed at the level indicated by black arrows. Black arrowheads point to the disrupted Myf5 expression. Brackets indicate loss of Myf5 expression in posterior somites. Myf5 expression is not activated in posterior somites of Gli2^–/–Gli3^–/– embryos and is reduced or delayed in Gli2^–/–Gli3^+/– and Gli2^+/–Gli3^–/– embryos at E8.5 and E9.5. In addition, upregulation and ventral expansion is observed in E8.5 anterior somites and in E9.5 interlimb somites of Gli2^–/–Gli3^+/– and Gli2^–/–Gli3^–/– embryos.