Sox9 mRNA expression in the developing palate and craniofacial muscles and skeletons

Background. Sox9 is a critical transcription factor for chondrogenesis and sex determination. Haploinsufficiency mutations of SOX9 in humans lead to campomelic dysplasia. Inactivation of Sox9 in the craniofacial region of mice results in an absence of endochondral bones and in malformation of other structures. This suggests that Sox9 plays multiple roles in craniofacial development and these remain to be elucidated. In order to study the functions of Sox9 in craniofacial development, a preliminary expression examination was performed. Material and Methods. To detect the expression of Sox9 mRNA, antisense riboprobe was synthesized by in vitro transcription. Radioactive in situ hybridization was performed on sagittal and coronal sections of mice head from organogenesis to the early postnatal stage. Results. It was found that Sox9 was expressed in multiple stages and distinct processes. Besides the expression in cartilage, it was seen in the fusing stage of palatogenesis. Sox9 was also present during differentiation and maturation of craniofacial muscles. In addition, it was observed in intramembranous skeletal elements at restricted sites and stage. Conclusions. The expression pattern suggests that Sox9 serves broad roles in craniofacial development.