The temporal expressions of myf5 and myod during cranial muscle development. The temporal expressions of myf5 (A–C, E, G, I) and myod (D, F, H, J) transcripts were analyzed by whole-mount in situ hybridization in zebrafish embryos. The transcript of myf5 was detected in the craniofacial region at 24 hpf (A, arrow); in the io, the precursor of lr, and 1st arch (lr/1st arch) at 30 hpf (B); in the so, io, lr, 1st, 2nd, and 3rd arches at 32 hpf (C); in the so, io, sh, 2nd, and 3rd arches at 36 hpf (E); and in the so, io, and sh at 42–48 hpf (G, I). myf5 was not expressed in the lr and 1st arch at 36 hpf (E). Meanwhile, myod was expressed in the craniofacial muscles mr/ir/sr, lr, and 1st arch at 32 hpf (D); in the mr/ir, sr, lr, MP, IM, CHD, and CHV at 36 hpf (F); and in all the cranial muscle at 42–48 hpf (H, J). CD: the constrictor dorsalis, which differentiates to lap and do; CHD: the constrictor hyoideus dorsalis, which differentiates to ah and ao; CHV: the constrictor hyoideus ventralis, which differentiates to ih and hh; IM: the intermandibularis, which differentiates to ima and imp; MP: the masticatory plate, which differentiates to CD and am. lr, lateral rectus; for other abbreviations, see the legend of Fig. 1.