Which phase of the menstrual cycle involves the shedding of the uterine lining?

The menstrual phase is characterized by the shedding of the uterine lining, which occurs when pregnancy does not take place during the preceding cycle. During this phase, the levels of hormones such as estrogen and progesterone drop significantly, triggering the sloughing off of the endometrial tissue. This process results in menstrual bleeding, typically lasting from three to seven days. The shedding of the uterine lining is essential for preparing the uterus for a potential new cycle, allowing for the regeneration of the endometrium in the subsequent phases.

In contrast, the follicular phase involves the development of follicles in the ovaries and the thickening of the uterine lining, but it does not include shedding. The luteal phase follows ovulation and is characterized by further thickening of the uterine lining in anticipation of a fertilized egg, and if fertilization does not occur, it leads into the menstrual phase. Ovulation marks the release of the egg but does not involve any shedding of the uterine lining.