[The sources of osteogenic cells in endochondral osteogenesis]

In the cartilage anlagen of the femoral bone of albino rat fetuses, the appearance of a primary locus of endochondral substitution was observed. The cellular composition in the locus is represented mainly by endothelial and perivascular forms. It was confirmed by the methods of cytology, autoradiography and cytophotometry that the perivascular cells penetrating into the cartilage resorption lacunae together with blood-vascular capillaries appeared to be initial forms and a primary sources for the emergence of osteoblasts in the endochondral replacement zone.