The control of growth in transplanted mammalian cartilage.

Sevento eight-day mouse tail vertebrae were transplanted under the renal capsules of syngeneic adult animals and allowed to grow for up to 6 months. Their curve of growth and histological pattern of ageing were similar to those of control vertebrae which had been left in their normal position on young animals. Slices of the growth cartilage of sevento eight-day rat tail vertebrae were similarly transplanted into adult syngeneic rats. Though some grafts failed to grow, a considerable number showed similar growth characteristics to the epiphyseal cartilage in intact control vertebrae. These results have been used to support the view that in the mouse and rat the epiphyseal growth cartilage has a limited potential for growth. This intrinsic growth-limiting mechanism seems to be of relatively greater importance than age-dependent changes in blood hormone levels in determining the changes in the rate of growth of the vertebrae as the animals approach adulthood.