A QUANTITATIVE STUDY OF THE INHIBITION OF THE OVARY AND OF THE TURGESCENT PERINEUM OF THE NORMAL BABOON PRODUCED BY A SINGLE INJECTION OF ESTRADIOL BENZOATE1

Abstract

A single inj. of estradiol benzoate given to mature baboons in the first part of the cycle upset the normal behavior of the perineum and, with one exception, the cycle was lengthened. 1-5 mg. of estradiol caused a temporary rise of the perineum (3-4 days) and then a slow deturgescence and finally perineal rest 10-15 days after the inj. Thereafter, without the intervention of bleeding, a new but slightly abbreviated and almost normal perineal rhythm was initiated. The exptl. cycle was lengthened. In 2 of 3 baboons 0.1 mg. of estradiol benzoate caused partial temporary deturgescence of the perineum and then the cycle continued normally thereafter, although lengthened. In 1 baboon, perineal deturgescence was complete and bleeding occurred 16 days after inj., the cycle was shortened. In 2 baboons 0.05 mg. of estradiol produced no visible alteration in perineal rhythm or in length of menstrual cycle. A single inj. sufficient estradiol benzoate inhibited the ovary for 10-16 days. Postponement of menstruation by repeated adm. of estrogen was dependent on maintenance of the supply of exogenous estrogen. On withdrawal, bleeding was precipitated. The minimum amt. of exogenous estrogen necessary to inhibit ovarian activity on the 8th-10th day was estimated as being approx. 0.1 mg. or less of estradiol benzoate. This technic of inhibiting the ovary might be employed for determining the amt. of estrogen secreted by the ovary on any particular day in the 1st part of the cycle in the human [female].