Defective expression of NC SoxE family genes in foxd3zdf10;tfap2alow double mutant embryos. (A,B,D-F) Dorsal views with anterior to the top of 6, 5 and 9 somite stage (s) embryos. (C) Lateral views with anterior to the left of 30 hpf embryos. (A) NC sox9b expression is severely depleted in foxd3zdf10;tfap2alow double mutants at the 6 somite stage, but is retained in the non-NC-derived otic placode (asterisks). (B) NC sox9b expression remains reduced in both single mutants, whereas NC expression is undetectable in double mutants by the 9 somite stage. (C) NC sox9a expression in the branchial arches (arrows) is absent in double mutant embryos. (D) There are slight reductions in NC sox10 expression in foxd3zdf10 and tfap2alow single mutants at the 5 somite stage, whereas in double mutant embryos NC sox10 expression is much more reduced. (E) By the 9 somite stage, NC sox10 expression is undetectable in double mutants. (F) In contrast to SoxE gene expression, NC foxd3 expression is maintained in foxd3zdf10;tfap2alow double mutant embryos, demonstrating that NC induction occurs.
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