Fig. 1. Wnt11 and En1 are expressed in complementary domains in the chick medial dermomyotome. Dorsal views at HH18 of the forelimb (fo) level, and corresponding transversal sections, hybridized with Wnt11 (A-C), En1 (D-F), Sim1 (G-I) and MyoD (J-L) probes. Rectangles outline one somite that involves three regions along the mediolateral axis. (A-C) Wnt11 transcripts are detected in the dorsomedial lip (dml) (region 1) in the dermomyotomal cells closest to the dorsal neural tube (nt). Isolated Wnt11-expressing cells are also detected dorsomedially to the lip, under the ectoderm (ec). (D-F) En1 is expressed in a central compartment of the dermomyotome (region 2), in a domain distinct from that of Wnt11. (G-I) The lateral third of the dermomyotome expresses Sim1 (region 3) and is distinct from the En1 domain. (J-L) MyoD positive cells are detected under the dermomyotomal epithelial sheet. nc: notochord. Scale bars: 100 µm in A,B,D,E,G,H,J,K; 50 µm in C,F,I,L.