Figure 5. Proposed embryology of agenesis of inferior vena cava and enlarged collateral veins.
Right common iliac vein (1); left common iliac vein (2); inferior vena cava (3); hemiazygos vein (4); azygos vein (5); accessory hemiazygos vein (6); abdominal wall collaterals (7); lumbar and paralumbar veins (8)
