Cytokinetic analysis of osteogenic cells in the healing process after fracture

As the result of cytokinetic analysis of osteogenic cell at the time of reintegration after experimentally administered bone fractures in mice, the following findings were obtained: 1) Gt of mesenchymal-like cells 1 week after fracture was 23 h but that 2 weeks later was 15 h. This shortening of Gt was due to the shortening of Gt1. Gt of osteoblasts, one week after, was 20 h and that 2 weeks after was 21 h. This prolongation of Gt was due to the prolongation of St. Despite the fact that Gt of mesenchymal-like cells 2 weeks after fracture was shortened, St indicated prolongation. 2) Both mesenchymal-like cells and osteoblasts indicated a reduction of growth fractions 2 weeks later. From these facts, it is considered that in the reintegration of the fracture, these proliferative cells control their own growth fractions according to the necessity of repair of the fractured part. 3) It was argued that chondrocytes originated from mesenchymal-like cells but should not be the precursors of osteoblasts. 4) It was shown that mesenchymal-like cells must have the potential to differentiate into either osteoblasts or chondrocytes. 5) Mesenchymal-like cells are the precursors of osteoblasts and the latter are the precursors of osteocytes, but mesenchymal-like cells and osteoblasts have their own respective cell cycles. 6) It was argued that the relation between S-32 uptake by the matrix of the osteoid and chondrocytes as functional cells should be studied in relation to the role played by cartilage tissue in the mechanism of ossification.