Previously it had been demonstrated that daily intramuscular injections of testosterone propionate (T.P.) will not induce male like mounting nor clitoral hypertrophy in pregnant animals to the extent these changes are induced in non-pregnant females. In an attempt to clarify the role of the ovary and placentae in this phenomenon the behavioral and somatic responses of pregnant ovariectomized and hysterectomized (pseudopregnant) guinea pigs to the masculinizing action of testosterone propionate was followed.
Female guinea pigs of the first experimental group were hysterectomized on the sixth day of their ovarian cycle and ovariectomized 60 days later. A second group of females was mated and then ovariectomized on the 46th day of gestation. Normal pregnant females and sham operated controls were also followed.
All groups received daily injections of T.P. starting on day 18 and continuing for the duration of the experiment (116 days).
Masculinization was evaluated on the basis of a sex behavior test given every 10 days starting on day 26 and a daily inspection of the external genitalia.
Among all groups the results indicated significant differences in response to testosterone propionate dependent upon the presence or absence of a gestagen producing structure such as the corpora lutea of the ovary in the hysterectomized female or the placenta in the pregnant animal. The role of progesterone in this connection is discussed.