Morphogenesis of the vena cava inferior roots in human embryogenesis

The roots of the vena cava inferior are formed during the 2nd month of human embryogenesis in the course of transformation of posterior caudal veins and their tributaries, including anastomoses with umbilical veins, which is associated with the growth of pelvic kidney and lower extremities. The roots and initial part of vena cava inferior originate from secondary cardinal veins, primarily from sacrocardinal anastomosis and sacrocardinal veins proximal regions.