IMMUNOHISTOCHEMICAL LOCALIZATION OF BONE MORPHOGENETIC PROTEINS AND THE RECEPTORS IN EPIPHYSEAL GROWTH-PLATE

The expression of bone morphogenetic proteins (BMPs) and BMP receptors (BMPRs) in the epiphyseal growth plate has not been clarified In this study,; we studied immunohistochemically the spatial and temporal loc alization of BMP-2/4, osteogenic protein-1 (OP-1, or BMP-7) and BMP re ceptors (BMPR-IA, BMPR-IB, and BMPR-II) in the epiphyseal plate of gro wing rats. The proximal parts of tibia in growing rats were observed. At 12 weeks after birth, BMP-2/4 and OF-I were expressed markedly in p roliferating and maturing chondrocytes. BMPR-IA, LB and II were clearl y co-expressed in proliferating and maturing chondrocytes, and the exp ression was decreased in hypertrophic chondrocytes. At 24 weeks, the e xpression of BMP-2/4 and OF-I war decreased, but BMPRs were still well -expressed in proliferating chondrocytes. The temporal and spatial exp ression of BMP and BMPR suggests that BMP and BMP receptors play roles in the multistep cascade of enchondral ossification in the epiphyseal growth plate.