The menstrual cycle in the monkey; effect of double ovariectomy and injury to large follicles.

Abstract

In the course of some experimental work upon the effect of injections of ovarian and placental hormones into monkeys, operations have been performed at several intervals of the menstrual cycle. In four monkeys both ovaries were removed; in a fifth, large follicles were injured. The effect of these operations upon the time of appearance and the duration of the next menses provide some evidence as to the cause and nature of menstruation. The ovaries were removed from the first monkey on the first day of the menstrual cycle (dated from the appearance of bleeding). The operation apparently had little effect for the menses continued to the fourth day. No second bleeding followed this one during a control period. Double ovariectomy was performed upon the second and third monkeys on the 10th and 14th days of the cycle respectively. At this time the skin of the external genital organs and surrounding regions was considerably reddened. Ovulation had recently occurred in both cases and the corresponding tubes were removed and the ova recovered. Apparently typical menstrual bleeding began on the 4th day after operation in the second monkey and on the 5th day in the third monkey. The duration of these menses was 8 and 3 to 4 days respectively. Both ovaries were removed from a fourth monkey at a time when the regions surrounding the genitalia were greatly swollen and reddened. Vaginal smears for several days before the operation were free from leucocytes. Although the time of operation in this animal cannot be dated in the cycle from an observed menstruation, the condition described would indicate a time near or after the middle of the cycle, probably included between the 10th and 20 days.