Fig. 6. The -63kb to -48kb region is necessary for Myf5 expression in limb buds, central nervous system and domains of the somite. Comparison of X-gal staining profiles between embryos of BAC195APZ (A,C,E) and BAC195PZ63-48 (B,D,F) transgenic lines at different stages of embryonic development. (A,B) At E9.0, the transgene is activated in the epaxial somitic lip as directed by the early epaxial enhancer (Teboul et al., 2002). (C,D) At E11.5, limb and brain expression are missing from the deleted BAC line. Expression in the thoracic somites at this stage does not comprise the full epaxial-hypaxial myotome extension, whereas staining shows a clear caudal bias as shown on higher magnification of these regions of E11.5 embryos (E,F). Expression in the thoracic somites at this stage does not comprise the full epaxial-hypaxial extent of the myotome (indicated by the red lines in E,F). (G,H) Transverse cryostat sections, stained with Eosin and X-gal from the thoracic level (white lines in C,D) of the embryos shown in C,D. Arrows in H indicate the full extent of the myotome (see G).