The corpus luteum (Latin for ‘yellow body’) is a temporary hormone-producing structure that forms in the ovary after a follicle releases an egg during ovulation. Its progesterone production is essential for establishing and maintaining early pregnancy.
How It Forms:
After the LH surge triggers ovulation and the mature egg is released, the empty follicle collapses and transforms into the corpus luteum. This structure produces high levels of progesterone and moderate levels of estrogen for about 12-14 days (the luteal phase of the menstrual cycle).
What It Does:
The progesterone from the corpus luteum prepares the uterine lining to receive and nourish a fertilized egg. It makes the lining thicker, more vascular, and secretory – creating an optimal environment for implantation. Progesterone also slightly raises body temperature, which is why basal body temperature increases after ovulation.
Its Fate:
If pregnancy doesn’t occur, the corpus luteum degenerates after about 14 days, forming the corpus albicans (white body). As it breaks down, progesterone and estrogen levels plummet, triggering menstruation. However, if pregnancy occurs, the embryo produces hCG (human chorionic gonadotropin), which rescues the corpus luteum and maintains progesterone production until the placenta can take over hormone production around 8-10 weeks of pregnancy.
