Fig. 4. The -58/-54 region drives Myf5-nlacZ expression to several sites of myogenesis in the somites, limb buds and hypoglossal cord. (A,C,D) X-gal staining of an embryo with a -58/-54 Myf5-nlacZ transgene at E9.75 (A, 26 somites), E10.5 (C, 30 somites) and E11.5 (D, 36 somites). At E9.75, ß-galactosidase-positive cells are detected in the developing myotome in the central epaxial region, as shown in a transverse cryostat section (stained with Eosin) (B) of the same embryo shown in A (white line indicates level of sectioning). At E10.5 (C), Myf5-nlacZ expression is still restricted to the same area of the myotome. It is detected in the extremities of the more mature somites at E11.5 (D). (E) Phase contrast microscope view of a section in the interlimb region of the embryo shown in D (white line indicates level of sectioning) where both the epaxial lip of the epithelial dermomyotome and the hypaxial somitic bud contain cells with blue nuclei (black arrowheads). At this stage, there is strong X-gal staining in the forelimb buds and labelling is also detectable in the less mature hindlimb buds. Cells in the hypoglossal cord are also positive for ß-galactosidase. (F) X-gal staining of an embryo at E11.5 (40 somites), with a -63/-54 Myf5-nlacZ transgene showing a pattern which is essentially similar to that shown in D. With these two constructs, Myf5-nlacZ activity is also detected in the brain and neural tube, owing to the central nervous system element (-56.6/-53.7), and in the branchial arches, owing to the control branchial arch sequence. There is also ectopic labelling of head mesenchyme, which is particularly notable in C. NT, neural tube; HC, hypoglossal cord.

Return to article