Abstract: The development of the skeleton is regulated by numerous signaling molecules expressed in epiphyseal cartilage controlling both chondrogenesis and osteogenesis such as fibroblast growth factor receptors (FGFRs). In order to explore the important effect of fibroblast growth factor receptor 2 (FGFR2) in the process of mandibular condylar growth, we introduced gain-of-function Fgfr2^+/S252W mice, and investigated mandibular condylar morphology by means of safranin-o/fast green staining at the stage of 1 week, 3 weeks and 6 weeks. The mutant mice displayed narrower width of the mandibular condylar growth plate, stronger stainings of trabecular bone at the stage of 1 week, 3 weeks and 6 weeks and faster degradation of the calcified cartilage cell layer at the stage of 6 weeks. We also assessed the expression of type X collagen (Col X) in mandibular condyle at the stage of 3 weeks by immunohistochemical staining and real-time PCR. The results showed that Col X was increased in the mutant mice. In conclusion, the gain-of-function mutation in FGFR2 resulted in histopathological abnormalities and development deformity of mandibular condyle cartilage in mice, which inhibited endochondral bone formation.

Key words: mandibular, condyle, fibroblast growth factor receptor 2