Grafting of a single anterior pituitary gland from another female to the renal capsule of an intact mouse causes irregularity in the oestrous cycles. The commonest external manifestation of this modification is the recurrence of pseudopregnancy-like cycles. This is due to the continued secretion of prolactin by the transplanted pituitary, which prolongs the life-span of the corpora lutea. Controls bearing a similar graft of cerebellum remain unaffected. The luteotrophic activity of the hypophysial graft is shown by positive deciduoma response of the uterus and by the histological appearance of the graft. On removal of the graft, the female promptly returns to the 4- to 5-day cycles.
Evidence is presented that the ectopic pituitary graft in the intact female mouse remains functional for long periods, in these experiments at least for more than 12 months. In spite of the continued secretion of prolactin by the pituitary graft, there is cyclic recurrence of oestrus at intervals of 2 or 3 weeks during which periods ovulation occurs and fertile mating takes place, if the female has access to a male.