Organizing Action of Prenatally Administered Testosterone Propionate on the Tissues Mediating Mating Behavior in the Female Guinea Pig1

The sexual behavior of male and female guinea pigs from mothers receiving testosterone propionate during most of pregnancy was studied after the attainment of adulthood. As a part of the investigation, the responsiveness of the females to estradiol benzoate and progesterone and to testosterone propionate was determined. The larger quantities of testosterone propionate produced hermaphrodites having external genitalia indistinguishable macroscopicalty from those of newborn males. Gonadectomized animals of this type were used for tests of their responsiveness to estradiol benzoate and progesterone and to testosterone propionate. The capacity to display lordosis following administration of estrogen and progesterone was greatly reduced. Male-like mounting behavior, on the other hand, was displayed by many of these animals even when lordosis could not be elicited. Suppression of the capacity for displaying lordosis was achieved with a quantity of androgen less than that required for masculinization of the external genitalia. The hermaphrodites receiving testosterone propionate as adults displayed an amount of mounting behavior which approached that displayed by the castrated injected males receiving the same hormone. The data are uniform in demonstrating that an androgen administered prenatally has an organizing action on the tissues mediating mating behavior in the sense of producing a responsiveness to exogenous hormones which differs from that of normal adult females. No structural abnormalities were apparent in the male siblings and their behavior was essentially normal. The results are believed to justify the conclusion that the prenatal period is a time when fetal morphogenic substances have an organizing or “differentiating” action on the neural tissues mediating mating behavior. During adulthood the hormones are activational. Attention is directed to the parallel nature of the relationship, on the one hand, between androgens and the differentiation of the genital tracts, and on the other, between androgens and the organization of the neural tissues destined to mediate mating behavior in the adult.