What are the three main paired veins in embryonic development?

The embryonic venous system originates from three paired veins: vitelline veins (draining the yolk sac), umbilical veins (carrying oxygenated blood from the placenta), and cardinal veins (draining the embryo proper). All drain into the sinus venosus and remodel to form the adult venous system.

How does the portal vein develop?

The portal vein forms from anastomoses between the vitelline veins around the duodenum. It includes contributions from the caudal left vitelline vein, middle dorsal anastomosis, and a segment of the right vitelline vein, with branches differentiating into the right and left portal branches.

What is the fate of the umbilical veins after birth?

After birth, the left umbilical vein regresses to form the ligamentum teres hepatis, and the ductus venosus becomes the ligamentum venosum. The right umbilical vein typically regresses earlier during development.

What are the key components of the azygos system?

The azygos system includes the azygos vein (from the right azygos line and cranial posterior cardinal segment), hemiazygos vein (from the lower left azygos line and caudal dorsal anastomosis), and accessory hemiazygos vein (from the upper left azygos line and cranial dorsal anastomosis). These veins drain into the superior vena cava and connect to the inferior vena cava.

What are some common clinical anomalies related to venous development?

Common anomalies include double SVC (failure of transverse anastomosis), left SVC (regression of the right anterior cardinal vein), double IVC (persistence of the left posterior cardinal vein), absent IVC (failure of hepatorenal anastomosis), and retrocaval ureter (infrarenal IVC forms from the anterior subcardinal vein).

How is the inferior vena cava (IVC) formed during development?

The IVC is composed of six embryonic segments derived from various veins, including the right posterior cardinal vein, right supracardinal vein, and right hepatocardiac channel. These segments fuse through anastomoses to form the definitive IVC.

What role do cardinal veins play in embryonic development?

Cardinal veins drain blood from the embryo proper. The anterior cardinal veins drain the cranial body and contribute to internal jugular veins, while the posterior cardinal veins drain the caudal body and help form the inferior vena cava. They join to form common cardinal veins that empty into the sinus venosus.

Venous Development – Vitelline, Umbilical & Cardinal Veins

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