Hypertrophic chondrocytes, commonly considered as terminal cells designated to apoptotic elimination in the model of endochondral osteogenesis, are accordingly to the new concept based on histochemical, immunohistochemical, biochemical and cytological analysis, able to switch their metabolism and enter the osteoblastic differentiation path. According to this concept, some osteocytes in model of endochondral osteogenesis are derivative of hypertrophic chondrocytes. Also non-hypertrophic chondrocytes are able to transdifferentiate toward osteogenic cells, and the bone formed by such mechanism is termed "transchondroid bone".