Physiology

Abstract

It was stated above that the sole function of the uterus is to receive, embed and nourish the fertilized ovum. To achieve these aims, every month during the child-bearing years the lining of the uterus, the endometrium, thickens and becomes filled with nourishing secretion. If pregnancy does not occur, menstruation follows in which the endometrium is shed. At the start of menstruation, the cycle and build-up of the endometrium recommences and preparations are again made to receive a possible pregnancy. How (and to a certain extent why) this occurs is discussed below under three separate headings:

• (1) The cyclical changes that occur monthly in the ovary and the hormones involved.

• (2) The effect that these hormones have upon the endometrium.

• (3) The changes the ovum undergoes if fertilized, and how preparations are made for the fetus to embed and grow in utero.