Difference in shape of bone formed by isolated calvarial and scapular osteoblasts transplanted under various conditions.

To study the influence of transplantation conditions on early stages of osteogenesis, isolated calvarial or scapular osteoblasts were injected into the leg or dorsal muscles (free transplants) or implanted after seeding on fragments of devitalized parietal bones (supported transplants) into dorsal muscles. The cross-sections of bone islands formed by calvarial osteoblasts in the different types of transplants were then compared according to their maximal breadth and length. Moreover, the same dimensions of pieces of bone formed by scapular osteoblasts in supported transplants were compared with those of bones formed in free transplants into leg muscles. Finally, comparison of the dimensions of cross-sections of supported transplants of calvarial and scapular osteoblasts was done. Calvarial osteoblasts in dorsal muscles produced a slightly higher percentage of wider and longer islands than those in leg muscles. In supported transplants of calvarial osteoblasts the percentage of narrow bone islands (breadth less than 100 microns) was considerably higher than in free transplants. Similarly, the percentage of narrow cross-sections in bones formed by scapular osteoblasts was higher in supported than in free transplants. In supported transplants of calvarial osteoblasts the percentage of narrow islands was higher than in similar transplants of scapular bone cells. It is suggested that the differences in shape of pieces of bone formed in supported and free transplants reflect the difference in mechanical conditions to which the bone cells were subjected. Furthermore, in supported transplants devitalized parietal bones could form a barrier for diffusion of nutrients.(ABSTRACT TRUNCATED AT 250 WORDS)