Fig. 4. Gli2^–/–Gli3^–/– embryos fail to activate the Myf5 EE enhancer/lacZ transgene. X-gal staining of E9.5 wild-type (A,C,E,G) and Gli2^–/–Gli3^–/– (B,D,F,H) embryos was performed to assess the activity of the Myf5 early epaxial enhancer. (A,B) Whole-mount X-gal staining shows that expression is lost in posterior somites (bracket). (C-H) Transverse sections were performed at the level indicated by the black line in posterior somites (C,D), interlimb somites (E,F) and anterior somites (G,H). In Gli2^–/–Gli3^–/– embryos, ß-gal⁺ cells are absent from posterior somites (black arrowheads) and greatly reduced in anterior somites.