IMP SYNOPSIS. Structure and Layers of the Uterus, Decidua. 1. Structure of the Uterus The uterus is a hollow, muscular organ of the female reproductive system, located in the pelvic cavity between the bladder and rectum. It is responsible for implantation, fetal development, and childbirth. A. Anatomical Divisions of the Uterus: B. Dimensions of the Uterus: 2. Layers of the Uterus The uterus has three layers: A. Perimetrium (Serosa) B.