Reduction of Jag1b-Notch2 signaling rescues the ventral defects of edn1 mutants. (A-F) Ventral views of dissected zebrafish facial skeletons at 5 dpf, with elements labeled in wild type (A). jag1bb1105 mutants (B) have Pq reductions (arrowhead) and variable transformations of Hm (arrow) and Op (asterisk). In edn1-/- mutants (C), M (red arrow) and Ch (red arrowhead) are nearly absent. In edn1-/-; jag1bb1105 larvae (D), development of ventral M and Ch is variably restored yet Pq and Hm defects are still evident. M and Ch development is also partially restored in some edn1-/-; jag1bb1105/+ (E) and edn1-/-; notch2-MO (F) larvae. (G) Quantification of skeletal rescue, showing wild-type (yellow), weakly defective (red), severely defective (blue), and expanded (green) cartilage and bone. (H) In situ hybridizations showing dlx3b, dlx5a and dlx6a expression in arch CNCCs at 36 hpf. Compared with edn1-/- embryos, edn1-/-; jag1bb1105 embryos show partial rescue of expression. Endodermal pouches are outlined. See Fig. 1 for abbreviations.