THE INTERACTION OF THE OVARIAN HORMONES IN EXPERIMENTAL MENSTRUATION1,2

Abstract

Castrated adolescent monkeys (Macaca mulatto) on continuous estrogenic treatment with 1000 I.U. of estradiol daily were given, between the 20th and 30th days, 1 I.U. of progesterone daily for periods of 1-5 days. Menstruation in the presence of estrogen occurred, on an avg., on the following days after the discontinuance of progesterone: 5 days[long dash]3.5; 3 days[long dash]4.2; 2 days[long dash]5.4; 1 day[long dash]7.7. The injs. of estrogen can be omitted for 2 days at the end of 20 days without precipitating menstruation, but when the treatment has continued for several wks., bleeding may follow such skipped periods on an avg. of 2.37 days. This indicates that the endometrium becomes equally sensitive to a withdrawal of estrogen as to a withdrawal of progesterone, but with estrogen the process requires several wks., and with progesterone it is a matter of days. Progesterone under these conditions also produced marked loss of edema of the sexual skin. Maximal deturgescence was attained within about 10 days regardless of whether progesterone was given for 1 or 5 days. The bearing of these observations on the problem of menstruation is discussed.