mef2ca expression in early CNC and late head muscles. In situ hybridization showing mef2ca expression in wild-type (A,B,D) and edn1 mutant (C) embryos at 20 hpf (A-C) and 55 hpf (D). (A-B) Dorsal (A) and lateral (B) views of mef2ca expression in all three migrating streams of CNC at 20 hpf. (C) CNC expression in edn1 mutants appears unaffected. (D) Lateral view of mef2ca expression in head muscles at 55 hpf. For A-C, arches are numbered. Pharyngeal pouches are outlined in B-C. For description of the larval head muscle pattern see (Lin et al., 2006; Schilling and Kimmel, 1997). am adductor mandibulae; cd, constrictor dorsalis; chd, constrictor hyoideus dorsalis; hh, hyohyoideus; ih, interhyoideus; ima, intermandibularis anterior; imp, intermandibularis posterior; ir, inferior rectus; mr, medial rectus; sh, sternohyoideus.