Fig. 5. Incubation of embryo explants with GoH3 leads to precocious myogenic differentiation in the dermomyotome. (A-D) Co-immunohistochemistry for Myf5 and myogenin on cryostat sections of E9.5 wild-type embryo explants cultured for 14 hours (A,B, transverse; C,D, longitudinal). Control explants (A,C) show normal expression of Myf5 and myogenin, including a few Myf5-expressing cells in the dermomyotomal lips (arrowheads in C). In the presence of GoH3 (B,D), myogenin is ectopically expressed in the dermomyotome (arrows) and Myf5-expression has extended (arrowheads). This effect is particularly evident in interlimb-level somites. (E,F) Graphical representation of the increase in fluorescence intensity for Myf5 and myogenin in the dermomyotome compared with the neural tube in control versus GoH3-treated explants. This value was obtained for whole dermomyotomes (E) and for dermomyotomes excluding lips (F). ep, epaxial; nt, neural tube; dm, dermomyotome; myog, myogenin. ^*P0.05; ^**P0.01; bars represent s.d. of means. Scale bars: 100 µm in A-D.