CERTAIN ACTIONS OF TESTOSTERONE ON THE ENDOMETRIUM OF THE MONKEY AND ON UTERINE BLEEDING1-21,2

IT HAS BEEN reported that testosterone or testosterone propionate prevents the uterine bleeding of estrone withdrawal in macacus monkeys and inhibits the onset of menstruation in the normally cyclic monkey (1). In woman it is stated that the normal cycle is interrupted, with disappearance of the secretory (progestational) phase, often with regression and atrophy of the endometrium and postponement of, or but scanty menstruation (2).Zuckerman (3) prevented the recurrence of bleeding in one normal monkey for 210 days during twice weekly injections of 25 mg. of testosterone propionate. A second animal was treated for 114 days, during which time no cyclic bleeding occurred. Bleeding did occur 8 days after the last injection. In the first animal at least, ovarian function was seriously disturbed. The endometrium illustrated by Zuckerman, while not atrophic, appears very inactive. Similar inactivation, or mild involution of the endometrium was reported by us after chronic estrogen treatment (4)