Testicular testosterone concentration and in vitro response to HCG in normal and in testosterone immunized rabbits.

The testosterone concentration, the in vitro response to HCG and the percentage Leydig cells in testes of normal and of testosterone-3-BSA immunized rabbits were determined. Following immunization all three parameters increased in the same order of magnitude (1.8-2.6fold). The results indicate that active immunization with testosterone has no deleterious effects on the endocrine capacity of the Leydig cells. The observed functional and morpholigical alterations of the testes are due solely to increased trophic hormone secretion from the pituitary caused by antibody binding of circulating androgens. The basic testosterone concentration in the testes of the control rabbits were in the range of values reported for other species.