Peritoneum
Peritoneum, serous membrane in the abdominal cavity. It consists of two layers, a parietal one lining the walls of the cavity and a visceral one closely investing the majority of the abdominal organs, and mooring them firmly in position. Between the two layers there is provision for a space, the peritoneal cavity; in the male this is closed, while in the female there is a direct communication between the sac and the fallopian tubes to enable the ova to reach the cavity of the uterus