Fig. 7. The H1 element in the transgene Myf5-V drives correct expression in limb muscles but not in somites. Whole-mount lacZ stainings of E9.5 (A), E10.5 (B) and E13,5(C) embryos illustrate transgene activation in posterior margins of somites but no expression in cervical somites. Transverse sections at different axial levels indicate the expression in the dermomyotome at early stages (a,a'). At later stages, some expression is also seen in myotomal cells (b'). A sagittal section of the embryo in (B) shows prominent expression in the posterior part of somites (b, rostral to the left). Sections through fore- and hindlimbs of the E13.5 embryo demonstrate that all limb muscles express the transgene (c,c').