Fig. 1.

Cleared and stained (C&S) pectoral girdle from WT (euthyroid), TH− (hypothyroid), and TH+ (hyperthyroid) zebrafish. Bone is stained with Alizarin red, and cartilage is stained with Alcian blue. Note the overall lack of ossification in TH− and the overossification in TH+. (A, D, and G) Pectoral girdle in dorsal view. Note the lack of the anteroventral curve to the cleithrum in TH− and the more angular curve in TH+ (box). Radials failed to ossify in TH−, with the exception of a very small region on the third proximal radial (circle). (B, E, and H) Postcleithra in medial view. Note the secondary ossifications in TH− and the more robust ossification in TH+. (C, F, and I): Pectoral girdle in medial view. Note that the cleithrum’s lateral plate is foreshortened in TH− and more robust in TH+. The coracoid foramen (cf) is also larger in TH− and surrounded by traces of cartilage, and smaller in TH+. Abbreviations: cf, coracoid foramen; cl, cleithrum; co, coracoid; fr, finrays; mco, mesocoracoid; rad I–IV, radials I–IV; sca, scapula; sf, scapular foramen.