Superovulation induced by a single pituitary gland transplanted beneath the kidney capsule in adult rats

Abstract

Different numbers of rat pituitary glands, taken from male and female rats before and after puberty, were transplanted into various sites in female rats at different stages of the oestrous cycle. Ovulation was checked by counting ova in oviducts on the next expected day of ovulation. Ovulation was induced by transplantation beneath the kidney capsule in early dioestrus of half, one or three glands from 35- to 41-day-old male rats (18·6 ± 3·1 (s.e.m.), 32·6 ± 2·8 and 49·8±4·8 ova shed respectively). The transplantation of glands from mature female rats did not induce superovulation but inhibited the expected ovulation. The most effective stage for inducing superovulation was early dioestrus and, to a lesser extent, oestrus; transplantation during late dioestrus was ineffective. The effective sites of transplantation were beneath the kidney capsule and intramuscularly but not subcutaneously. Representative pituitary glands from 35- to 41-day-old male rats and adult female rats were assayed for LH and FSH content to interpret the mechanisms of superovulation. The pituitary glands from the male rats contained larger amounts of LH and especially of FSH than those found in the female rats. The experiments indicated that superovulation can be induced successfully by the transplantation of a single pituitary gland from male and immature female rats without any additional treatment with human chorionic gonadotrophin; the failure of the female pituitary transplants to induce superovulation may be due to the insufficient content of LH and FSH.