Fig. 6

The role of cartilage in the specification and organization of tendon and ligaments. col2a1-positive pharyngeal cartilage was lost in sox9a- (B) and sox9a-sox9b-deficient embryos (88%, n=56) (C) compared with controls (A). (D-F) sox9a- and sox9a-sox9b-deficient embryos (93%, n=42) express scxa but in an altered pattern compared with controls. sox9a-sox9b-deficient embryos were identified by the loss of their otic vesicle, which only occurs in the absence of both genes. Similar expression was observed for morpholino-mediated knockdown of sox9a and sox9b together, and with sox9a or sox9b morpholino injection into crosses of sox9a^hi1134 or sox9b^fh313 mutants, respectively. (G,H,J,K) At 72hpf and 96hpf, sox9a- and sox9a-sox9b-deficient embryos (82%, n=57) express scxa and tnmd, but in an abnormal pattern compared with controls. The scxa- and tnmd-expressing ligaments (H,I,K,L, arrows) appear shorter and wider than controls. Expression posterior and lateral to the ligaments in K,L marks the branchiostegal rays.