Fig. 3

Fig. 3  Abnormal pharyngeal arch development in sym1 mutants. Wild-type (A, B) and sym1 mutant (C, D) embryos at 5 dpf, stained with Alcian blue to reveal craniofacial cartilages. Ventral (A, C) and lateral (B, D) views show that the 1st (mk) and 2nd (ch) arch derivatives are present but abnormal in sym1 mutants, whereas 3rd arch-derived cartilages (cb1–5) are missing altogether. dlx2 expression in migrating neural crest pharyngeal arch precursors, shown in dorsal views at 24 hpf in wild-type (E) and sym1 mutant (G) embryos, and in lateral views of 32 hpf wild-type (F) and sym1 mutant (H) embryos. sym1 mutants have reduced dlx2 expression in migrating neural crest cells that generate the 1st and 2nd arch derivatives (labeled 1 and 2), and more severely reduced dlx2 expression in neural crest cells that generate the pharyngeal cartilages (labeled 3 and 4; G, H). Abbreviations: Meckel's cartilage (mk), palatoquadrate (pq), ceratohyal arch (ch), ethmoid plate (ep), and ceratobranchial (cb) arches 1–5.