Fig. 7. hand2 is not required for early ventral pharyngeal arch expression of edn1 targets. Lateral views of deyolked wild type (A,C,E,G,I,K), hand2 mutant (B,D,F,H,J,L) and edn1-MO-injected (M) animals. In each panel, the eye is in the upper left and the ear is in the upper right. (A,B) The ventrally restricted pharyngeal arch expression domain of dlx3 at 30 hpf (A) does not require hand2 function (B). (C,D) EphA3 expression at 32 hpf (C) also does not require hand2 function (D). (E-H) gsc expression. (E,F) Early dorsal and ventral hyoid expression domains of gsc at 32 hpf (E) are present in hand2 mutants (F). (G,H) At 38 hpf, ventral arch one expression of gsc is absent in hand2 mutants (arrows), whereas both dorsal and ventral arch two expression are still present (H). The seventh pharyngeal arch expression domain is downregulated in hand2 mutants. (I,J) msxe expression at 30 hpf. hand2 mutants have upregulated ventral arch msxe expression. (K-M) msxb expression at 30 hpf. Ventral pharyngeal arch expression of msxb (K) requires Edn1 signalling (M), but is upregulated in hand2 mutants (L). Relevant pharyngeal arches are numbered in each panel. The second pharyngeal endodermal pouch fails to completely separate the second and third arches in hand2 mutants (arrowheads in C,D and I,J). Scale bar: 50 µm.

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