Induction of Precocious Sexual Maturity in the Mouse by Daily Pituitary Homeo and Heterotransplants. ∗

Abstract

Homeotransplants. Sexual maturity is induced in the female mouse by daily pituitary homeotransplants even more rapidly than in the rat. In the rat 8 to 10 daily transplantations are required to bring about sexual maturity at the weaning date (22nd day of life); if the transplants are commenced at about the weaning date, 4 to 6 transplantations only are necessary. 1 In the mouse 3 transplantations made on successive days induced sexual maturity whether begun at the weaning date (20th day of life) or 3 days previously. The structural and physiological changes resulting from this treatment are those characteristic of normal sexual maturity. The vaginal canal is established and contains the cells typical of oestrus, the uterus is engorged, and many large follicles and corpora are present.

In the immature male mouse, as with the male rat, the response of the genital system to the pituitary transplants is much slower than with the female. Four daily transplantations into males varying from 18 to 22 days of age give no, or only a slight increase in size of the testes, and but a small increase (about 25 per cent) in the remainder of the genital system. When the transplants are given even for 17 successive days the testes do not show the marked weight increase over the untreated control that is shown by the remainder of the genital tract, the latter being some 10 times heavier than that of the controls. Even though the testes show, as compared with the rest of the genital system, only a relatively small increase in weight from the transplantations, nevertheless it appears that the implanted pituitary affects the genital tract through the intermediary of the testes, for in their absence no growth response results in the remainder (7% the genital system.