Fig. 1

The temporal expressions of six1a, myf5 and myod during cranial muscle development of zebrafish. The temporal expressions of six1a (A, D, G, J, L), myf5 (B, E, H) and myod (C, F, I, K, M) transcripts of zebrafish were analyzed by whole-mount in situ hybridization in embryos from lateral view (A–K) and ventral view (L–M). The transcript of six1a in the olp, ov, and allg at 24 hpf (A); in the mr, ir, 1st, 2nd, and 3rd arches at 32 and 36 hpf (D, G); and in all the cranial muscles at 72 hpf (J, L). The myf5 transcript was detected in the craniofacial region at 24 hpf (B, arrow); in the so, io, 2nd and 3rd arches at 32 hpf (E); and in the so, io, and 3rd arches at 36 hpf (H). Although the myod was not expressed in the craniofacial muscles at 24 hpf (C), it was detected in the mr/ir, lr, and 1st arch at 32 hpf (F); in the mr, ir, sr, lr, MP, IM, CHD, and CHV at 36 hpf (I); and in all the cranial muscles at 72 hpf (K, M). The schematic diagram illustrates the expression of six1a in the cranial muscles during 32–72 hpf (N). ah, adductor hyoideus; allg, anterior lateral line and vestibular ganglia; am, adductor mandibulae; ao, adductor operculi; do, dilator operculi; dpw1–5, dorsal pharyngeal wall 1–5; hh, hyohyoideus; ih, interhyoideus; ima, intermandibularis anterior; imp, intermandibularis posterior; io, inferior oblique; ir, inferior rectus; lap, levator arcus palatini; lr, lateral rectus; mr, medial rectus; olp, olfactory placode; ov, otic vesicle; sh, sternohyoideus; so, superior oblique; sr, superior rectus and tv 1–5, transversus ventralis 1–5. 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. CD: the constrictor dorsalis, which differentiates to lap and do.