Which of the following is not a part of uterine wall?

Mesometrium is not a part of uterine wall. The uterine wall consists of three distinct layers. 

• The outermost layer, known as the perimetrium, is composed of simple squamous epithelium and areolar connective tissue. It forms part of the visceral peritoneum and covers the uterus, extending laterally into the broad ligament. 
• The middle layer, called the myometrium, is comprised of three layers of smooth muscle fibers, with the thickest portion in the fundus and the thinnest in the cervix. These muscle layers contract during labor to facilitate childbirth. 
• The innermost layer, the endometrium, is highly vascularised and consists of three components: a luminal epithelium, an endometrial stroma of lamina propria, and uterine glands. The endometrium is divided into the stratum functionalis, which lines the uterine cavity and is shed during menstruation, and the deeper stratum basalis, which is permanent and gives rise to a new stratum functionalis after each menstrual cycle. Together, these three layers make up the histological composition of the uterus.