Rat-tail tendon repetitively labeled with 14C-proline over a four-week period was used to create functional homografts to non-radioactive rat Achilles tendon. These were followed by histologically, autoradiographically, and by analysis of specific radioactivity at periods ranging from one month to two years.
The homograft tendons were repopulated by host cells which incorporated the transplant into a gradually maturing tendon structure. After an initial fall in specific activity due to dilution in the first ninety days, there was no decrease in specific activity over the two-year period of observation. Turnover of rat-tendon homograft collagen, thus, does not appear to occur in a period greater than one-half the lifespan of the animal, unless local reutilization of collagen is postulated without a change in specific activity.