The menstrual cycle of the primates - X—The oestrone threshold of the uterus of the rhesus monkey

Uterine bleeding occurs in spayed rhesus monkeys a few days after the cessation of a series of oestrin injections (Allen 1927). The fact that bleeding also follows either the removal of ovaries which do not contain functional corpora lutea or injury to large ovarian follicles (Allen 1927; van Wagenen and Aberle 1931) is now related to the occurrence of post-oestrin bleeding, and these various observations, together with parallel and in some cases long-established clinical findings, have been made the basis of what is known as the oestrin-withdrawal theory of menstruation. The experimental study of the menstrual cycle necessarily requires detailed knowledge of the varying reactions of the primate uterus to oestrin. The available observations on this question are very few, and for that reason the following study was undertaken.