The reproductive cycle of the crab-eating macaque (Macaca fascicularis)

Characteristic changes in the menstrual cycle of the crab-eating macaque were evaluated. Cyclical changes in type and abundance of exfoliated cells in vaginal smears as well as the ferning pattern of cervical mucus were observed. These indices were useful in predicting approximate ovulation time. The cyclical changes in sexual skin swelling and/or coloration were detected only in adolescent females. Micro-sections from ovaries of autopsied animals revealed large Graafian follicle formations often rupturing by day fourteen of the cycle. Length of the menstrual cycle ranged from 26–38 days with a modal value of 28 days.This research has been supported by Ford Foundation Grant No. 710-0287.