Craniofacial defects in irxl1 MOI morphants can be rescued by cRNA injection. myoD expression in head muscle precursors of 48-hours postfertilization (hpf) embryos was used as a score to classify the craniofacial defects. Wild-type (WT), myoD expression observed in all head muscle precursors; Type 1, partial loss of ventral pharyngeal arch muscle precursors (im, chv, sh); Type 2, loss of some extraocular muscle precursors (so, sr, io, ir) in addition to type 1; Type 3, complete lack of head muscle precursors. Embryos were injected with 0.5 or 1 pmol of irxl1 MOI plus 0.75 or 1.5 pmol of p53 MO. In rescue experiments, 290 pg of irxl1 cRNA (145 pg irxl1a plus 145 pg irxl1b) was co-injected. ah, adductor hyoideus; am, adductor mandibulae; ao, adductor operculi; cd, constrictor dorsalis; chv, constrictor hyoideus ventralis; im, intermandibularis; io, inferior oblique; ir, inferior rectus; lr, lateral rectus; MO, morpholino oligonucleotides; mr, medial rectus; sh, sternohyoideus; so, superior oblique; sr, superior rectus. Scale bar = 100 μm.
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