Box for secondary retroperitoneal organs: These organs were intraperitoneal during early development. Later on their mesenteries were pushed back against the posterior abdominal wall so that they became retroperitoneal. These organs are the pancreas, duodenum, ascending and descending colon.
Embryonic remnants
| Embryonic Origin | Remnant |
| Foramen ovale | Fossa ovalis |
| Ductus arteriosus | Ligamentum arteriosum |
| Ductus venosus | Ligamentum venosum |
| Umbilical vein | Ligamentum teres hepatis |
| Umbilical arteries | MediaL umbilical ligament, part of internal iliac and superior vesical arteries. |
| Mesonephric or Wolffian ducts | In males it becomes efferent duct including the epididymis, vas deferens and seminal vesicles. In females, it remains as epoophoron and paroophoron, Gartner’s ducts. |
| Paramesonephric or Mullerian ducts | In females, it becomes the fallopian tubes, uterus, cervix, upper part of vagina. In males remnants seen in the prostatic utricle. |
| Urachus or allantoic stalk | MediaN umbilical ligament |
| Notochord | Nucleus pulposus |