Initiation of inferior vena cava (IVC) appears with embryo 5 mm length (4 weeks) as excrescence of vitelline- umbilicial trunk. It unites sinusoids of caudate lobe of liver. 6 week embryos´ IVC includes right subcardinal vein. "Ascension" of growing kidneys at the 7th week into abdominal cavity is accompanied by fast pass of sacrocardinal and intersubcardinal anastomosis, mesocardinal veins - longitudinal vein anastomosis, connecting supracardinal (ascendant lumbar) and subcardinal veins, upper (paranephric) and lower (gonadal). Right parts of subcardinal and sacrocardinal sinuses, right lower mesocardinal vein compose IVC. Subcardinal sinus is devided into left renal vein (central part) and retroperitoneal lymphatic sac, sacrocardinal sinus - into left general iliac vein and subaortic sac. Left lower mesocardinal vein is switched off from the blood flow and turns into left lumbar trunks. Abdominal parts of posrcardinal veins are reducted, chest parts become azygos and hemiazygos veins. Chest subcardinal veins are switched off from the blood flow and turn into two thoracic ducts. Thus, IVC is formed in the sub-basin of posrcardinal veins involving hepatic sinusoids in the process of intensive growth of caudate lobe of liver, adrenals and kidneys, displacing mesonephros.
The work is presented for an International Science Conference "Contemporary problems of experimental and clinical medicine", Thailand, February 20-28, 2010. Received by the editorship on 11.01.2010.