Fig. 2.
Morphogenetic movement of the pharyngeal arches fail in smo mutants. (A–H) Confocal images of fli1:EGFP transgenic embryos that are (A, C, E & G) wild type and (B, D, F & H) mutant at the smo locus. (A & B) In fixed and anti-EGFP stained 36 hpf embryos, aside from the loss of the maxillary domain (mx), the pharyngeal arches (numbered) of wild types and smo mutants closely resemble one another. (C, D) At 48 hpf, the pharyngeal arches elongate similarly in both wild type and smo mutant embryos, although morphogenesis of the mandibular (md) region of the first arch may be disrupted. (E) By 54 hpf, the second arch of wild-type embryos has widened, along the anterior/posterior axis, and the third pharyngeal arch has moved medial to the second arch. (F) 54 hpf smo mutants have not undergone these morphological changes and resemble 48 hpf mutants. (G & H) Orthogonal views showing the relative position of the 3rd arch in 54 hpf wild-type and smo mutant embryos. The first four pharyngeal arches are numbered. Anterior is to the left in all images; dorsal is up in A-F; lateral is up in G & H. Scale bar=50μm.