Uterus:This organ, with a hollow interior, is situated in the lower abdomen of women, nestled between other organs. The lower, narrower section of the uterus is called the cervix, often referred to as the neck of the uterus. The upper, wider portion is known as the corpus, consisting of three tissue layers. In women of reproductive age, the innermost layer, the endometrium, undergoes cyclical changes each month, a process known as the menstrual cycle. During this cycle, the endometrial tissue thickens in anticipation of a fertilized egg. If fertilization does not occur, this tissue breaks down and exits the body. The middle layer, known as the myometrium, comprises muscular tissue that stretches during pregnancy to accommodate the developing fetus and contracts during childbirth to facilitate delivery. The outermost layer, the perimetrium, also expands during pregnancy and contracts afterward.