Simultaneous loss of prrx1a/b and jag1b further improves ventral cartilages in edn1 mutants.
(A-E) Ventral views of dissected facial skeletons. edn1 mutants have much reduced ventral cartilage in the first (black closed arrowhead) and second (black open arrowhead) arches. Whereas jag1b; edn1 and prrx1a; prrx1b; edn1 mutants show some restoration of ventral cartilage, primarily in the second arch, quadruple prrx1a; prrx1b; jag1b; edn1 mutants show a prominent rescue of second arch Ch cartilage (black open arrowhead) and increased length of first arch M cartilage (black closed arrowhead). (F) Quantification of skeletal rescue in prrx1a; prrx1b; edn1 mutants (left column) and jag1b; edn1 mutants with decreasing numbers of wild-type prrx1a/b alleles (e.g. 4 wild-type alleles = pure jag1b; edn1 mutants; 0 wild-type alleles = quadruple mutant). Examples of no, mild, moderate, or strong rescue of the ceratohyal cartilage are shown in (B-E). Numbers in each genotype, from left to right: 11, 13, 17, 15, 6. (G-J) edn1 mutants show a loss of ventral barx1 expression (magenta, white open arrowhead) and a partial reduction of dlx5a (green), which are partially restored in prrx1a; prrx1b; edn1 triple mutants. The magenta channel is shown by itself in (G'-J'). Scale bar in E = 100 μm; scale bar in J' = 20 μm.