Fig. 3.

Shh is necessary to trigger the differentiation of Pax7⁺ DM-derived progenitors. (A-H) E2.5 embryos subjected for 16 hours to pluronic gel alone (control) or cyclopamine in pluronic gel. Desmin⁺ myotomes were smaller in the presence of cyclopamine (dorsal views in A,B), contained more Pax7⁺ progenitors (C,D and higher magnifications in C′,D′), and exhibited reduced expression of Myf5 and MyoD mRNAs (E-H). (I-T) Expression of PTC^Δloop2 cell-autonomously represses myogenic differentiation in both the medial (I-N) and lateral (O-T) myotome. (U) Quantification of the percentage of Pax7⁺ cells in myotome out of total GFP⁺ cells. ^*P<0.003. Error bars represent s.e.m. Dashed line in R-T represents the lateral limit of the desmin⁺ myotome. DM, dermomyotome; M, myotome; VLL, ventrolateral lip. Scale bar: in C,D,O-T, 50 μm; in E-H, 60 μm; in I-N, 40 μm.