Fig. 7

hand2 mutants and hand2 mutants injected with dlx3b;4b;5a-MO show homeotic skeletal phenotypes. (A-F) Alcian Blue and Alizarin Red staining at 6 dpf. Images are flat mounted bilateral pharyngeal arches, oriented with midline to the center, and anterior upwards. (A) The wild-type skeleton was too large for a single image at this magnification, so two images were overlaid for this panel (border indicated with a broken grey line). (B) hand2^C99 homozygotes have reduced ventral, but normal intermediate and dorsal domain skeleton. (C) In trans-heterozygous fish carrying hand2^C99 and hand2^S6, defects are typically more severe than in hand2^C99 homozygotes, but less severe than in (D) hand2^S6 homozygotes. In hand2^S6 homozygotes, broad cartilages often span the midline, similar in shape to duplicated palatoquadrates, complete with pterygoid processes (arrows). (E) When hand2^C99 homozygotes are injected with dlx3b;4b;5a-MO, joints are lost in both arches, and the remainder of Meckel′s cartilage is tapered out into a shape similar to a pterygoid process. A broken line indicates the first arch dorsal-ventral plane of symmetry. (F) The cartilage expansions of hand2^S6 are lost when dlx3b;4b;5a-MO is injected. The palatoquadrate of hand2^S6;dlx3b;4b;5a-MO is often severely defective, though the distance between the first and second arch-derived skeleton seen on the left side of F is exaggerated by mounting artifacts. Scale bar: 100 μm.