📖 Definition
A temporary endocrine gland that forms in the ovary from the follicle after an egg is released at ovulation. The corpus luteum produces progesterone and estrogen during the luteal phase, preparing the uterine lining for implantation. If fertilization occurs, hCG from the developing embryo sustains the corpus luteum; otherwise, it degenerates and progesterone drops, triggering menstruation.