Sertoli cell secretion of a factor that inhibits the incorporation of 3H-thymidine into cells in vitro.

Overview

Rat Sertoli cells secrete a low molecular weight factor in vitro that inhibits the incorporation of 3H-thymidine into cells. Although the addition of Sertoli cell-conditioned medium (rSCCM) resulted in nearly a threefold stimulation of cell growth, the incorporation of 3H-thymidine was decreased in a dose-dependent manner and did not reflect the increase in cell number. Peritubular cell- and germ cell-conditioned medium did not contain this inhibitory activity. Nor did the conditioned medium from fibroblasts and a variety of cell lines tested. A low molecular weight filtrate of rSCCM (< 1,000 Da) contained virtually all of the 3H-thymidine inhibiting activity, as well as about 50% of the mitogenic activity in the rSCCM. The inhibitory activity was eliminated upon removal of the rSCCM and was not due to either growth inhibition or a toxic effect on cell proliferation.