What is one role of estrogen during the menstrual cycle?

During the menstrual cycle, one of the primary roles of estrogen is to foster the growth of the endometrium, which is the inner lining of the uterus. At the beginning of the cycle, levels of estrogen increase in response to the developing ovarian follicles. This rise in estrogen prompts the thickening and proliferation of the endometrial tissue in preparation for a potential implantation of a fertilized egg.

Estrogen is crucial for creating an optimal environment for a potential pregnancy by enhancing the vascularity and nutrient supply of the endometrium. As the cycle progresses, particularly in the follicular phase, the secretion of estrogen continues to support the growth of the endometrium, making it receptive for implantation if fertilization occurs. Once ovulation takes place and if conception does not occur, the decline in estrogen levels leads to the shedding of the endometrial lining during menstruation.

This physiological function highlights the essential nature of estrogen in preparing the uterus for possible early stages of pregnancy.