MENSTRUATION

Abstract

This review deals primarily with human menstruation, though other primates are mentioned frequently, and other orders of mammals occasionally. It has these avowed objectives: "To summarize the observations on the uterine vascular system and their significance for the understanding of menstruation, to discuss the facts which are supposed to be explained by certain current hypotheses, and to review the evidence that all menstrual cycles are not directly comparable with one another." This it does by treating the following topics: Definition of menstruation; duration of cycle and of flow; composition, mechanism, amount, and incoagulability of discharge; histo-physiological changes of uterus, vagina, and Fallopian tube; nervous system; menstruation after anovulatory cycles; hypotheses to explain the adaptive significance of menstruation; hypotheses to explain its physiological "cause.".