If fertilization doesn’t occur, the uterus lining, which has thickened in preparation for a potential pregnancy, sheds off and is expelled through the vagina as menstrual blood. This process is known as menstruation. The thickening of the lining and subsequent shedding are part of the regular menstrual cycle.
Here’s a more detailed explanation:
Preparation:
The uterus prepares itself for a fertilized egg by developing a thick, spongy lining called the endometrium. This lining is rich in blood vessels and nutrients, ready to support the developing embryo if fertilization occurs.
No Fertilization:
If the egg is not fertilized by a sperm cell, the corpus luteum (a temporary structure in the ovary that produces hormones) begins to decline.
Shedding:
The decrease in hormones causes the blood-rich lining of the uterus to shed, along with the unfertilized egg, as menstrual blood. This process is known as menstruation.
Menstruation:
Menstruation typically lasts for a few days and marks the beginning of a new menstrual cycle.