Vitelline veins the developing liver and broken up by it into a plexus of small capillary-like vessels termed sinusoids. The vitelline veins give rise to Inferior mesenteric vein, Ciliac trunk The branches conveying the blood to the plexus are named the venae advehentes, and become the branches of the portal vein. The vessels draining the plexus into the sinus venosus are termed the venae revehentes, and form the future hepatic veins. Ultimately the left vena revehens no longer communicates directly with the sinus venosus, but opens into the right vena revehens. The persistent part of the upper venous ring, above the opening
Smallest cardiac veins Smallest cardiac veins The smallest cardiac veins (or Thebesian veins) are minute valveless veins in the walls of all four heart chambers. The veins are sometimes accurately referred to as vessels, but they are frequently confused with a distinct set of artery connections eponymously referred to as the "vessels of Wearn". In his 1928 publication, Wearn himself referred to the arterio-cameral connections (vessels of Wearn) as thebesian. However, Wearn's 1933 and 1941 publications emphatically described the thebesian veins as distinct from arterio-cameral vessels. The thebesian veins are reportedly most abundant in the right atrium and least in the left ventricle.