LENGTHENED CALLUS ACTIVATED BY AXIAL SHORTENING - HISTOLOGICAL AND CYTOMORPHOMETRICAL ANALYSIS

The tibiae of rabbits were lengthened by 10 mm in 2 weeks, then approx imately one half of the limbs were shortened by 2 mm in 3 days, and le ft for 3 days. Histological and cytomorphometrical findings of the cal luses in both groups were compared. In the shortened callus, marked hi stologic changes were observed in the central mesenchymal cell layer w here the number of the osteoblasts increased 4 fold, and massive primi tive fiber bone formation took place. Cartilaginous tissue did not see m to respond to the axial shortening stress.