Venous system: vitelline, umbilical and cardinal veins !

Embryonic structure

Three pairs of veins bring blood to the embryo's heart; in the end almost everything shifts to the right and forms the venae cavae.

Updated 2026-11-01

See it in 3D: Inferior vena cava · Superior vena cava · Portal vein · Brachiocephalic veins · Azygos veins · Coronary sinus · Left renal vein · Internal jugular vein · Liver

What it is

In week 4 three pairs of veins reach the sinus venosus: the vitelline (yolk sac and gut), umbilical (placenta) and cardinal veins (embryo body). Their remodeling shunts blood to the right side, forming the venae cavae, the portal vein and the ductus venosus. It explains common variants such as a persistent left superior vena cava and a double inferior vena cava or azygos continuation.

Key facts

Week 4: all three pairs of veins drain into the right and left horns of the sinus venosus.
Weeks 5–7: left-to-right anastomoses move blood toward the right horn.
Week 8: blood from the body, placenta and gut now arrives through the inferior and superior venae cavae.
The shrunken left horn remains as the coronary sinus.

Structure

Vitelline veins: form a plexus around the duodenum and pass through the septum transversum, where the liver grows.
Umbilical veins: run in the body wall; the left connects to the hepatic sinusoids and the ductus venosus.
Cardinal veins: anterior (head), posterior (body) and common; later subcardinal, supracardinal and sacrocardinal veins appear.

What it becomes

Superior vena cava, brachiocephalic and internal jugular veins (anterior and right common cardinals).
Inferior vena cava by segments (right vitelline, subcardinal and supracardinal veins).
Portal and superior mesenteric veins (vitelline); azygos and hemiazygos veins (supracardinal).
Ligamentum teres hepatis (left umbilical vein) and ligamentum venosum (ductus venosus).
Left common iliac vein (sacrocardinal anastomosis) and left renal vein (subcardinal anastomosis).

Step by step

The vitelline veins form a plexus inside the growing liver: the hepatic sinusoids.
The right vitelline vein enlarges and forms the hepatic segment of the inferior vena cava.
The right umbilical vein and the proximal left one disappear; the left drains through the ductus venosus.
An anastomosis between the anterior cardinals carries blood from left to right: the left brachiocephalic vein.
Subcardinal and supracardinal veins replace the posterior cardinals in the abdomen.
Left-sided anastomoses steer everything to the right-sided channel, which forms the inferior vena cava.

Clinical notes

Persistent left superior vena cava: the left anterior cardinal fails to regress; it drains into a dilated coronary sinus.
Left or double inferior vena cava: the left supracardinal vein persists.
Interrupted IVC with azygos continuation: the right subcardinal fails to join the liver; associated with heterotaxy syndromes.
Retrocaval ureter: the IVC forms from the posterior cardinal vein, which lies in front of the ureter.

Test yourself

Think of the answer, then tap the question to see it.

Which embryonic vein forms the hepatic segment of the inferior vena cava?

The right vitelline vein.

How does the left brachiocephalic vein form?

From an oblique anastomosis between the left and right anterior cardinal veins.

What does the left umbilical vein become after birth?

The ligamentum teres hepatis; the ductus venosus becomes the ligamentum venosum.

Where does a persistent left superior vena cava drain?

Into the coronary sinus, which looks dilated.

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See it in 3D

The structures of Durgical's 3D anatomy where it is found.

← All of embryology

Educational content on embryonic development; not a guide to prenatal diagnosis or to medicines in pregnancy and no substitute for a health professional's advice. No doses are given.

Sources: Langman's Medical Embryology, 13th ed., ch. 13: Cardiovascular System (Wolters Kluwer, 2015); Congenital anomalies of the IVC—embryological perspective and clinical relevance (Cardiovascular Diagnosis and Therapy (AME Publishing), 2016).

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Representative model, for educational purposes only.