The corpus luteum is a temporary endocrine structure that forms in the ovary after the release of an egg during ovulation. It plays a crucial role in fertility during the luteal phase of the menstrual cycle. The corpus luteum produces hormones, primarily progesterone, which supports pregnancy and prepares the uterus for the implantation and nourishment of the fertilized egg. If fertilization does not occur, the corpus luteum degenerates, leading to a decrease in hormone production and the shedding of the uterine lining, resulting in menstruation. The corpus luteum is a normal part of the menstrual cycle and is essential for maintaining a healthy environment for a developing fetus.