Electron radioautographic study of experimental fracture healing

The mitotic activities of various cellular components of callus tissues in different periods after tibial fracture of rat were studied with 3H-thymidine labeling and electron radioautographic method. Silver grains were accumulated over the nuclear areas of mesenchymal cells, monocytes, macrophages, endothelial cells of capillaries, fibroblasts, chondroblasts and chondrocytes, as a result of incorporation of the labelling material during their mitosis. Although osteoblasts and osteocytes could not undergo mitosis, they also revealed silver grains over nuclear areas because of their derivation from the mesenchymal cells or osteogenic cells.