The effect of mechanical stimulation of the nipples on the ovary and the sexual cycle.

Abstract

A laboratory experiment was carried out in which normal female animals were exposed to long periods of stimulation of the nipples through suckling. Sexual cyclicity was found to be interrupted as a result of the mechanical stimulation. To be exact periods of diestrus separated by 1-2 day estrus periods occurred throughout the suckling experiment. All 4 of the following conditions--pregnancy copulation pseudopregnancy lactation and suckling pseudopregnancy--are distinguished by corpus luteum function. In all the uterus becomes progestational estrus in inhibited and the mammary glands are developed. Microscopic photographs illustrate the results of the study. In this case of suckling pseudopregnancy the continued nervous influence was necessary; removal of the suckling stimulus resulted in resumption of estrus between 2-5 days. The secretory activity of the mammary gland was not involved in the development of diestrus.