FURTHER STUDIES ON MARE SERUM GONADOTROPHINS SECRETED IN RESPONSE TO IMMUNIZATION WITH HCG OR CRUDE OVINE FSH

Summary. The gonadotrophic activity of sera from two mares treated either with human chorionic gonadotrophin or with crude ovine pituitary fsh as antigens has been studied in intact and hypophysectomized immature female and male rats. The studies were projected over a 4-year period during which time the mares were subjected to three and four sequences of immunization, respectively. One-third millilitre of serum from the mare treated with ovine fsh increases ovarian and uterine weights in intact immature female rats, while 5 ml of serum tends to depress these weights because of the anti-fsh present in the serum. Thirty millilitres of serum approximately doubles the seminal vesicle and prostate weights in intact males, whereas the testis weights are either unaffected or depressed. Based on the ventral prostate responses in Sprague-Dawley hypophysectomized males, the serum is estimated to contain about 25-\g=m\gequivalents of nih-lh-s8/ml. Both the serum of this mare and that of an untreate