Retroperitoneum (English)

Retroperitoneal organs are found posterior to the peritoneal cavity in the retroperitoneal space with only their anterior wall covered by the parietal peritoneum. If they develop and remain outside the peritoneum, they are referred to as the primary retroperitoneal organs. These include the kidneys, suprarenal glands, ureters, aorta/inferior vena cava and rectum. Secondary retroperitoneal organs initially develop within the peritoneum, however become retroperitoneal as they lose their mesentery during embryonic development. These include the pancreas, distal duodenum, ascending and descending colons.