U.S. Department of Agriculture: Agricultural Research Service, Lincoln, Nebraska


Date of this Version



Published in Journal of Animal Science (1984) 58:4, 949-954


The possibility that estradiol-17/3 may directly influence testicular steroidogenesis in bulls was investigated in vitro. Testicular tissues were incubated for 4 h and regression coefficients (b, ng·ml-1·h-1) based on the increase in testosterone in the medium were used to describe testosterone secretion rates. In the first experiment, testicular tissues from control bulls and bulls chronically implanted with estradiol were incubated in the absence (basal conditions) or presence of 10 mlU/ml human chorionic gonadotropin (hCG). Under basal conditions, testosterone secretion rates were similar for tissues from control (b = 24.1 ± 6.0) and implanted (b = 34.7 ± 6.0) bulls. Testosterone secretion rates were increased approximately fourfold during incubation with hCG; tissues from implanted animals secreted testosterone at a higher rate (P