Sexual responsiveness and temporally related physiological events during pregnancy in the rhesus monkey

In connection with the investigations in the embryology and the physiology of reproduction being carried on at the Carnegie Laboratory of Embryology, the writer has been privileged to study the sex behavior of rhesus macaques whose physiological condition is being followed. It is the purpose of this paper to report the findings on three of these animals which became pregnant during the observations and to correlate quantitative changes in sexual responsiveness with certain anatomical and hormonal events which have been worked out by other members of the staff. The method of measuring responsiveness was the same as that used in the study of cyclic changes in the normal, nonpregnant animal (Ball and Hartman, '35). It is a measure not of acceptance but of invitation. I n this papcr we showed that, while the female monkey may accept the male at any time in the menstrual cycle, there is, typically, a definite increase in SCX interest around the middle of the cycle just before ovulation. I n figure 1 similar curves are given for a menstrual cycle of three females, the curves being continued into pregnancy. It will be seen that one of these animals was observed thronghout pregnancy, one was surgically aborted on the sixty-ninth day of gestation and the third suffered spontaneous abortion on about the seventy-sixth day.