Functional Capacities of Ovaries of New-born after Transplantation into Adult Ovariotomized Rats. ∗

Smith and Engle 1 pointed out that in mice more than 10 days old, sexual maturity may be induced by hypophysis transplants, but at this early date 5 daily transplants are required. After the 17th day 2 or 3 daily transplants are sufficient. Hill 2 has shown that this age difference holds for injections of pregnancy urine. However, the ovary of the new-born rat responds neither to the amount required for the 15–20-day-old rat nor to a much higher dosage (Wiesner 3 and Pfeiffer, unpublished work). It remained to be tested how early the ovary of the new-born might mature if it were subjected to gonadotrophic hormones from the time of birth. This could be done by injections. However, if the ovaries are transplanted into an adult female at the time of castration, they will be supplied with a constant, or possibly a steadily increasing amount of anterior pituitary hormone.

Young, healthy, mature female rats whose cycles had been followed for some time previous to the operation were used for hosts. The ovaries were obtained from new-born young and one ovary was transplanted under the dorsal surface of each kidney of the host, on which bilateral ovariotomy was performed at the time of implantation. Seven animals were used and the grafting was successful in 5 cases. The changes in the ovary were followed by daily vaginal smears which also indicated the extent to which the immature ovary was able to fulfill the endocrine functions of the adult ovary. After 4½ to 8½ months the grafts and the hypophyses were removed, sectioned, and studied, in order to correlate the oestrus condition with the histological structure in the ovary and in the hypophysis. Proof that no regeneration of the ovaries had taken place was obtained by a study of sections through the region of the ovarian stalk and by comparison with a series of control castrates.