What is the main purpose of the corpus luteum in the menstrual cycle?

The main purpose of the corpus luteum in the menstrual cycle is the secretion of progesterone. After ovulation, the ruptured follicle transforms into the corpus luteum, which is crucial for maintaining the endometrium, or uterine lining. Progesterone prepares the endometrium to receive a fertilized egg, promoting its maintenance if pregnancy occurs. This hormone plays a pivotal role in regulating the menstrual cycle by thickening the uterine lining and preventing further ovulation during the luteal phase. If pregnancy does not occur, the corpus luteum degenerates, leading to a drop in progesterone levels, which triggers menstruation.

The other options pertain to different aspects of reproductive physiology but do not capture the principal role of the corpus luteum. For example, stimulating the production of FSH is primarily the function of the anterior pituitary gland rather than the corpus luteum. Keeping the menstrual cycle regular involves a complex interplay of various hormones and factors, with the corpus luteum contributing primarily through its progesterone secretion. Similarly, while facilitating ovulation is important within the reproductive cycle, it is the role of the follicle rather than the corpus luteum itself. Thus, the secretion of progesterone is the defining and critical function of the