Inverted-pear-shaped organ of the female reproductive system, in which the embryo and fetus develop during pregnancy. Lying over and behind the bladder, it is 2.5–3 in. (6–8 cm) long and about 2.5 in. (6 cm) across at the top, where the fallopian tubes enter it; at the other end, the cervix extends down into the vagina. The uterine lining (endometrium), a moist mucous membrane, changes in thickness during the menstrual cycle (see menstruation), being thickest at ovulation in readiness for a fertilized egg. The uterine wall, about 1 in. (2.5 cm) thick, expands and becomes thinner as a fetus develops inside. The cervix expands to about 4 in. (10 cm) for delivery. Disorders of the uterus include infections, benign and malignant tumours, prolapse, endometriosis, and fibroids (leiomyomas; see muscle tumour).

Variants of UTERUS

uterus or womb

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