Bone development following transplants of urinary bladder wall: a quantitative histological and ultrastructural study.

Bone formation occurred ten days after transplantation of guinea-pig urinary bladder wall to the anterior abdominal wall. A quantitative analysis showed that the bone which formed in the tissues of the transplant site grew rapidly during the following week. Thereafter, bone growth slowed and remodelling became evident histologically. The bone continued to enlarge for up to six months but growth was mainly confined to an increase in thickness. Matrix vesicles were observed in the early bone formation, but later, when bone growth slowed, these structures could not be observed on the bone surfaces.