utero

Utero is the Latin term for the uterus, the muscular, hollow organ of the female reproductive system that houses and nourishes a developing fetus. In English, the word uterus is standard, while the phrase in utero is used to describe events occurring inside the uterus.

Anatomy and structure: The uterus is located in the pelvis between the bladder and the rectum and is typically tilted forward (anteverted) and flexed (anteflexed) in adults. It consists of the fundus (top portion), the body, and the cervix, which opens into the vagina. The uterine wall has three layers: the perimetrium (outer serous layer), the myometrium (thick middle muscular layer responsible for contractions), and the endometrium (inner mucosal lining that thickens during the cycle and sheds during menstruation). The endometrium has functional and basalis regions. Blood supply comes primarily from the uterine arteries, with venous drainage through the uterine venous system; innervation is via the autonomic nervous system.

Development and function: The uterus develops from the Müllerian ducts during embryogenesis. Hormonal cycles cause the endometrium to thicken in preparation for potential implantation; if fertilization occurs, the uterus supports fetal development and participates in labor through myometrial contractions and cervical changes. If implantation does not occur, hormonal signals trigger endometrial shedding (menses).

Conditions and variations: Congenital anomalies (e.g., unicornate, bicornuate, or didelphys uteri) result from Müllerian duct development. Common conditions include uterine fibroids (leiomyomas) within the myometrium, adenomyosis, and, in some contexts, endometriosis affecting adjacent tissues. Diagnostic methods include ultrasound and MRI.

See also: womb; female reproductive system; in utero.