edn1 function is required for jaw joint bapx1 expression. (A-D) bapx1 expression in wild-type (A,C) and edn1 mutant larvae (B,D). (A,B) Lateral views of 36 hpf embryos, focused on the first arch joint domain (arrow in A). First arch mesenchymal expression of bapx1 is absent in edn1 mutants (B). Cells apposed to the eye and the first pharyngeal pouch express bapx1 in both wild types and mutants. (C,D) Ventral views of 54 hpf embryos. Joint domains (arrows in C,D) are abolished in edn1 mutants, whereas the first and second arch midline domains (white and black arrowheads, respectively, in C and D) are present. Inset (D) shows lateral view of same embryo, showing both midline domains are present. Scale bars: 50 μm.
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