Module
16
Icon module 16
Cardiovascular system

The umbilical system

The umbilical veins bring the nutrient- and oxygen-rich blood from the placental villi via the umbilical cord to the embryo. Normally there exists only one umbilical vein in the umbilical cord: the unpaired umbilical vein. At the caudal rim of the navel, though, it becomes connected to the two intraembryonic umbilical veins, which go laterally from the umbilical coelom to the heart and empty into the two sinus horns with the omphalomesenteric veins that lie medial from them.

Fig. 23 - Umbilical venous system Stage 12 (ca. the 30th day)
media/module16/p6a_Herzaussehen11.gif

  1. First aortic arch
  2. Outflow tract (distal section)
  3. Superior cardinal vein
  4. Inferior cardinal vein
  5. Upper intestinal sinus
  6. Ventricle (middle section)
  7. Sinus venosus
  8. Liver anlage
  9. Umbilical vein
  10. Omphalomesenteric vein

Legend
Fig. 23

Heart with major in- and out-flowing vessels.

In the further development the umbilical veins become quickly included in the developing liver, so that they obtain a connection to the liver's capillary plexus. Now the blood from the left and right umbilical vein gets into the sinus venosus directly on the one hand and via the anastomoses in the liver on the other.

The extrahepatic part of the umbilical veins atrophies rather soon (stages 13 - 14). The blood of the umbilical veins now reaches the sinus venosus mixed with the blood of the omphalomesenteric veins passing through the liver. The posthepatic part of the left omphalomesenteric vein atrophies and the right one takes over all of the blood flowing through the liver. (compare the development of the cardinal vein system interactive diagram).
In parallel a shunt, the ductus venosus, has formed within the liver. It directs a part of the nutrient- and oxygen-rich blood from the umbilical veins directly into the heart so that it reaches organs like the brain as quickly as possible.

Navigation
Synoptique

Overview of the illustrations presented in the interactive diagram.

Fig. synopvitellin13 - Development of the
omphalomesenteric system
media/module16/p6b1_VenenUmbilical13.gif

  1. Sinus venosus
  2. Superior cardinal vein
  3. Inferior cardinal vein
  4. Left common cardinal vein
  5. Right umbilical vein
  6. Liver
  7. Anastomose between the left and
    right omphalomesenteric vein
  8. Right umbilical vein
    (prehepatic)
  9. Left umbilical vein
  10. Right omphalomesenteric vein
  11. Umbilical vein (unpaired)
  12. Vena cava inferior
  13. Ductus venosus
  14. Portal vein
  15. Splenic vein

Legend
Fig. synopvitellin13
Fig. synopvitellin15 - Development of the
omphalomesenteric system
media/module16/p6b2_VenenUmbilical15.gif

  1. Sinus venosus
  2. Superior cardinal vein
  3. Inferior cardinal vein
  4. Left common cardinal vein
  5. Right umbilical vein
  6. Liver
  7. Anastomose between the left and
    right omphalomesenteric vein
  8. Right umbilical vein
    (prehepatic)
  9. Left umbilical vein
  10. Right omphalomesenteric vein
  11. Umbilical vein (unpaired)
  12. Vena cava inferior
  13. Ductus venosus
  14. Portal vein
  15. Splenic vein

Legend
Fig. synopvitellin15
Fig. synopvitellin18 - Development of the
omphalomesenteric system
media/module16/p6b3_VenenUmbilical18.gif

  1. Sinus venosus
  2. Superior cardinal vein
  3. Inferior cardinal vein
  4. Left common cardinal vein
  5. Right umbilical vein
  6. Liver
  7. Anastomose between the left and
    right omphalomesenteric vein
  8. Right umbilical vein
    (prehepatic)
  9. Left umbilical vein
  10. Right omphalomesenteric vein
  11. Umbilical vein (unpaired)
  12. Vena cava inferior
  13. Ductus venosus
  14. Portal vein
  15. Splenic vein

Legend
Fig. synopvitellin18
Fig. synopvitellin20 - Development of the
omphalomesenteric system
media/module16/p6b4_VenenUmbilical20.gif

  1. Sinus venosus
  2. Superior cardinal vein
  3. Inferior cardinal vein
  4. Left common cardinal vein
  5. Right umbilical vein
  6. Liver
  7. Anastomose between the left and
    right omphalomesenteric vein
  8. Right umbilical vein
    (prehepatic)
  9. Left umbilical vein
  10. Right omphalomesenteric vein
  11. Umbilical vein (unpaired)
  12. Vena cava inferior
  13. Ductus venosus
  14. Portal vein
  15. Splenic vein

Legend
Fig. synopvitellin20

The prehepatic portion of the right umbilical vein later atrophies completely and all of the placental blood gets to the liver via the left umbilical vein.
Following birth, the left umbilical vein is obliterated and the ductus venosus becomes the ligamentum venosum.