Final answer:
The mesometrium is the structure that divides the pelvic peritoneal space into posterior and anterior pouches, a key anatomical feature in the organization of the peritoneal cavity.
Step-by-step explanation:
The structure that divides the pelvic peritoneal space into the posterior and anterior pouches is the mesometrium. The peritoneal cavity is a potential space in the abdomen that is subdivided into various regions and pouches by peritoneal folds. The visceral peritoneum includes major folds that hold abdominal organs to the body wall. During fetal development, certain organs may be positioned behind the peritoneum, a condition known as retroperitoneal. Understanding these anatomical structures is crucial for comprehending the complex organization within the abdominal and pelvic cavities.