Corpus Luteum

Last Updated: June 8, 2019

Definition - What does Corpus Luteum mean?

The corpus luteum is a temporary structure responsible for releasing progesterone to support embryo implantation in the uterus. The corpus luteum develops from the remnants of a follicle, the sac inside the ovary that contains the developing egg.

The follicle turns into the corpus luteum shortly after ovulation has occurred and degenerates to the corpus albicans if fertilization does not occur.

FertilitySmarts explains Corpus Luteum

At the beginning of each menstrual cycle, the ovary prepares to release an egg. A fluid-filled sac, called a follicle, appears in the ovary. The follicle is responsible for containing the egg until it reaches full maturation. The body releases luteinizing hormone (LH), which triggers the softening of the follicle walls, prompting the egg to break free. Once the egg is released, the follicle becomes a corpus luteum.

The role of the corpus luteum is to support conception by ensuring the uterine lining is dense and nutrient rich in anticipation of potential implantation. To do so, the corpus luteum releases high doses of the hormone progesterone, which helps the endometrium complete its regrowth.

If the released egg becomes fertilized, the corpus luteum continues to secrete progesterone to support implantation. At around 10 weeks gestation the corpus luteum has reached its full size. The woman's body no longer requires the output of hormones, and the corpus luteum begins to shrink. Between weeks 16 and 20 the corpus luteum will reabsorb into the ovary.

If the released egg is not fertilized, the corpus luteum shrinks back into the ovary within two weeks.

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