The growth of transplanted mouse vertebrae: effects of transplantation under the renal capsule, and the relationship between the rate of growth of the transplant and the age of the host.

The tail vertebrae of 7to 8-day C3H mice were transplanted under the renal capsules of syngeneic animals of various ages. Morphological effects of transplantation included degeneration of the intervertebral joints, increase in the diaphyseal haemopoietic marrow and decreased formation of bone trabeculae. The growth rate of the transplanted vertebrae depended upon the age of the host. Those transplanted into animals of the same age as the donor grew faster than controls left on the tail. Those transplanted into young adults (aged 4 months) and senile adults (aged 17 months) grew at 71 % and 64 % respectively of the rate of those transplanted into 7to 8-day hosts. These differences are interpreted as due primarily to age dependent changes in blood hormone levels.