The wall of the uterus has three layers of tissue. The external thin membranous perimetrium, middle thick layer of smooth muscle, myometrium and inner glandular layer called endometrium that lines the uterine cavity. The endometrium undergoes cyclical changes during menstrual cycle. It is shed off during menstruation and is regenerated during the proliferative phase. The myometrium exhibits strong contraction during delivery of the baby. The mesometrium is the mesentery of the uterus.