Corpus luteum
Corpus luteum
Also known as: yellow body, corpus albicans, corpus haemorrhagicum
A temporary endocrine gland formed from the ruptured follicle after ovulation that secretes progesterone, estradiol and inhibin A for ≈14 days — or for ≈7–9 weeks if rescued by hCG in pregnancy.
Overview
After ovulation the follicle collapses and fills with a small clot (corpus haemorrhagicum). Under LH, its cells undergo luteinisation: granulosa-lutein cells (large, pale, centrally placed) produce progesterone and convert androgens to estradiol and secrete inhibin A, while the smaller, peripheral theca-lutein cells produce progesterone and androgens. The basement membrane breaks down and capillaries invade under VEGF, making the corpus luteum one of the most richly vascularised tissues in the body. It is yellow because of lipid and carotenoid (lutein) pigment and reaches ≈2–3 cm.
If fertilisation does not occur, the corpus luteum has a fixed lifespan: luteolysis begins ≈10–12 days after ovulation (falling LH pulsatility, local prostaglandin F2α), hormone output falls, menstruation follows and the gland is replaced by a white fibrous scar, the corpus albicans. If implantation occurs, hCG from the trophoblast acts on LH receptors and maintains it as the corpus luteum of pregnancy until the placenta takes over progesterone production at ≈7–9 weeks; it then slowly regresses.
- Location
Ovarian cortex at the site of the ovulated follicle.
Anatomy
- Histology
Large pale granulosa-lutein cells and smaller, darker theca-lutein cells at the periphery and along septa, with a dense capillary network; the corpus albicans is hyalinised collagen.
Function
- Secretes progesterone (secretory transformation of the endometrium, maintenance of early pregnancy).
- Secretes estradiol and inhibin A (suppressing FSH during the luteal phase).
- Secretes relaxin.
- Regulation
LH (luteal phase) and hCG (pregnancy) maintain it; luteolysis follows reduced LH support and prostaglandin F2α.
Clinical significance
Corpus luteum cyst
Haemorrhage into or rupture of a corpus luteum can cause acute pelvic pain and haemoperitoneum that mimics a ruptured ectopic pregnancy; a pregnancy test and ultrasound distinguish them.
Luteal support in IVF
Egg retrieval and GnRH analogues impair corpus luteum function, so progesterone is given after embryo transfer. Removing the corpus luteum before ≈7 weeks without progesterone replacement causes miscarriage.
Test yourself
Which hormone maintains the corpus luteum in early pregnancy?
- FSH
- Prolactin
- Human chorionic gonadotropin (hCG)
- Human placental lactogen
Answer: Human chorionic gonadotropin (hCG)
hCG from the syncytiotrophoblast acts on LH receptors of the corpus luteum, sustaining progesterone secretion until the placenta takes over at ≈7–9 weeks.
Compiled from standard anatomy and physiology references — see the Reproductive System sources. For education only; not medical advice.