Fig. 6. Impairments of the development of the craniofacial skeleton in bcox morphants. (A-D) Alcian Blue staining of the cartilage of the craniofacial skeleton of bcox morphants (B,D) when compared with controls (A,C). The Meckel's cartilage and palatoquadrates are deformed, the ceratohyales project posteriorly, and the ceratobranchials are reduced or absent (see asterisks). (E) Co-injection of bcox-MO with bcox mRNA rescued the morphant phenotype (arrows indicates the restored cartilage). (F,G) The pectoral fins of bcox morphants are shortened and project laterally. (H,I) ap2 expression in the pharyngeal region at 24 hpf (lateral view) is reduced in cranial neural crest in bcox morphants when compared with controls (see arrows). At 31 hpf (J,K dorsal view), dlx2 expression is reduced in the posterior arch primordia in bcox morphants (K, see arrows). At 2 dpf (L,M, lateral view), dlx2 expression is altered in anterior arch primordia, whereas it is reduced in the posterior arch primordia in bcox morphants (M) when compared with controls (L; see arrow in M). At 3 dpf (N,O, lateral view), dlx2 expression persisted in the pharyngeal region in bcox morphants (O, see arrow) whereas it is absent in controls (N). (P,Q, lateral view) Application of exogenous RA (10^–7 M) results in a downregulation of dlx2 expression in pharyngeal region of 3 dpf bcox morphants (Q, see arrow). ch, ceratohyal; m, Meckel's cartilage; nc, neurocranium; pec, pectoral fins; pq, palatoquadrate. In all pictures, anterior is towards the left.

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