Fig. 5.

Cleared and stained jaw and suspensorium from WT, TH−, and TH+ zebrafish. (A, E, and I) Lateral view of craniofacial features. Note the differences in shape of the operculum, with the dorsal most edge of TH− improperly ossified and the more robust and larger operculum in TH+. (B, F, and J) Dentary. Note the bony process on the mandibular symphysis, which only appears in older adult TH− zebrafish, and the enlarged dentary in TH+. (C, G, and K) Dorsal view of the upper jaw elements. Arrows indicate the symphysis between the premaxillae. Asterisks indicate the ascending process of the premaxilla. Note that the ascending process of the premaxilla fails to form correctly in TH−. The rostral and premaxillary processes of the maxilla also do not form properly in TH−, and so the premaxilla does not sit properly in the groove formed by these two maxillary processes. (D, H, and L) Anterior view of kinethmoids. Note lack of discrete lateral wings, unossified dorsal edge, and trabecular-like bone in the TH−, and the asymmetrical lateral wing formation in TH+. Abbreviations: hm, hyomandibula; k, kinethmoid; mx, maxilla; op, operculum; pg, premaxillary groove; pm, premaxilla.