The feelgood mutation affects craniofacial skeletal development. (A–D) Live images of wild-type (WT) and feelgood (felm662) embryos at 5 dpf. Arrows indicate reduced length of head and trunk in dorsal (A,B) and lateral (C,D) views. (E–F′) Alcian blue staining of cartilage elements in head skeleton in lateral (E,F) and ventral (E′,F′) views. cb, ceratobranchials 3–7; ch, ceratohyal; hs, hyosymplectic; m, Meckel’s cartilage; pq, palatoquadrate. (G,H) Toluidine blue staining of transverse sections of the jaw at the level of the optic nerve (asterisk). Nuclei stain blue, whereas ECM stains purple. Arrow indicates tightly packed nuclei in feelgood mutants.