Fig. 7 Expression of sox9a and sox9b in the developing pharyngeal arches. (A, B) Lateral view of the 45 h embryo. Both sox9a and sox9b were detected strongly in the pectoral fin buds (pf), most segments of pharyngeal arch primordia, such as mandibular (m), hyoid (h), and ceratobranchial (cb) arches, CNS, and otic vesicles (ov). Expression patterns of the two genes in the brain and otic vesicle are not identical. (C, D) Ventral view of head at 72 h. Differentiating cartilage elements of pharyngeal arches express both sox9a and sox9b; the level of sox9b expression is lower and concentrated in the ceratobranchial. Other abbreviations: cb, ceratobranchials; ch, ceratohyal; mc, Meckel’s cartilage; pq, palatoquadrate; tb, trabeculae. (E, F) Double staining of 76 h head with col2a1 in blue and sox9a in red (E), or col2a1 in red and sox9a in blue (F). Expressions of the two genes overlap in most cartilaginous tissues in the cranio-facial and pectoral fin skeletons. The distribution of col2a1 in these elements is less restricted than that of sox9a.
Reprinted from Developmental Biology, 229, Chiang, E., Pai, C.-I., Wyatt, M., Yan, Y-L., Postlethwait, J., and Chung, B.-C., Two sox9 genes on duplicated zebrafish chromosomes: expression of similar transcription activators in distinct sites, 149-163, Copyright (2001) with permission from Elsevier. Full text @ Dev. Biol.