Uterus:A hollow, pear-shapedorganthat is locatedina woman's lowerabdomen, between thebladderand therectum. The narrow lower portion of theuterusis thecervix(theneckof the uterus). The broader upper part is thecorpus, which is made up of three layers oftissue. In women of childbearing age, the inner layer (endometrium) of the uterus goes through a series of monthly changes known as the menstrual cycle. Each month, endometrial tissue grows and thickens in preparation to receive a fertilizedegg. Menstruation occurs when this tissue is not used, disintegrates, and passes out through thevagina. The middle layer (myometrium) of the uterus is肌肉发达的怀孕期间组织扩展到hold the growingfetusand contracts during labor to deliver the child. The outer layer (parametrium) also expands during pregnancy and contracts thereafter.
