EXPERIMENTAL STUDIES ON THE MENSTRUAL CYCLE OF THE BABOON (PAPIO PORCARIUS). VI. THE EFFECT OF PROGESTERONE UPON THE FIRST PART OF THE CYCLE IN NORMAL FEMALE BABOONS1
The normal adult [female] baboon, when given progesterone (prog.) in the first or turgescent part of the cycle, exhibits specific perineal reactions which may or may not be accompanied by bleeding at the end of 4 to 7 days after prog. adm. The perineal reaction consists of a sudden onset of deturgescence when the sex skin may become completely absorbed. The minimum quantity of prog. necessary to produce this effect is 3 mg. Bleeding occurs if a single dose of 20 mg. prog. is used and is precipitated on the 5th day after the inj. when the perineal swelling has reached its lowest ebb. Doses smaller than 20 mg. produce perineal deturgescence unaccompanied by bleeding. If 2 or 3 injs. are given at 3 or 4-day intervals then a total of 15 mg. of prog. is adequate to produce bleeding. Prog. withdrawal is capable of precipitating bleeding and in so doing the normal cycle of a baboon can be shortened to 1/3 its normal length. Where bleeding is not produced by the single adm. of prog. the cycle is prolonged by 3 to 7 days as a rule. The adm. of appreciably large quantities of prog. (10 mg.) early or late in the first part of the cycle has no effect on the bleed- ing. A minimal amt. of prog. is necessary to produce peri-neal deturgescence without bleeding and perineal de-turgescence with bleeding. Prog. acts in the presence of large quantities of estrone and the action of prog. is not fully explained by a quantitative inactivation of estrone. In the baboon, the uterus and perineum, after they have been sensitized to estrone, have a greater affinity for prog. than for estrone and prog. is active in the presence of large quantities of estrone. Two reactions of the baboon, perineal deturgescence without bleeding and perineal deturgescence with bleeding permit an easy and accurate assay of prog. uncomplicated by operative procedures.