The corpus luteum is found on the ovaries, which is in the pelvis in the lower abdomen of the body, on either side of the uterus.
The corpus luteum is not always present; it varies with the cyclical nature of menstruation. The corpus luteum is formed after ovulation, after the follicular fluid is discharged, the pressure in the follicular cavity decreases, the follicular wall collapses, and the follicular granulosa cells and endofollicular cells within it invade inward, surrounded by the outer follicular membrane of the connective tissue, which together form the corpus luteum.
If the expelled egg is fertilized, the corpus luteum transforms into the corpus luteum of pregnancy and degenerates by the end of the third month of pregnancy. If the discharged egg is not fertilized, the corpus luteum begins to degenerate 9 to 10 days after ovulation, gradually turning into leucosomes, and the function of the corpus luteum disappears, lasting only 14 days. After the luteum declines, menstruation occurs and the next cycle begins.