Factors Influencing Ovarian Response of Normal and Hypophy-sectomized Rat to Pregnant Mare Serum. ∗

Abstract

Summary

A study of the ovarian response of the normal and hypophyscctomized rat to PMS showed that subcutaneous administration is less effective than intraperitoneal. With small doses, 6 units distributed over 3 days and given at a 2-unit level in a single injection, the intraperitoneal route was twice as effective as subcutaneous in both normal and hypophysectomized. In the normal animal, PMS was twice as effective as in the hypophysectomized. The uterine response was not significantly affected by the mode of injection in the normal animal, but in the hypophysectomized intraperitoneal injection was 4 times as effective as subcutaneous. When the same daily dose is given for 12 days intraperitoneal injection was 3 times as effective as subcutaneous in the normal animal and 11 times as effective in the hypophysectomized. At this level, intraperitoneally administered PMS yielded ovaries of approximately the same weight in both groups. When the same total dose, namely 24 units, was distributed over a 4-day period, subcutaneous injection proved equally as effective as intraperitoneal in both normal and hypophysectomized rats. As a tentative explanation, it is suggested that the rate of absorption may be one of several factors involved in this mechanism.