vein http://upload.wikimedia.org/wikipedia/commons/c/c2/Venous_system_en.svg Part of the circulatory system composed of blood vessels which carry blood from other organs, tissues, and cells to the heart.[AAO] EV:0100031 vena ZFA:0000082 galen:Vein CALOHA:TS-1108 MESH:D014680 AAO:0010212 TODO - check with MA - vein vs venous blood vessel Wikipedia:Vein MAT:0000037 venous subtree uberon Any of the tubular branching vessels that carry blood from the capillaries toward the heart. AEO:0000209 EMAPA:35906 venae MIAA:0000037 venous vessel EFO:0000816 GAID:492 BTO:0000234 TAO:0000082 EHDAA2:0003254 UBERON:0001638 XAO:0000115 VHOG:0001743 SCTID:181367001 vascular element The appearance of Chordata and subsequently the vertebrates is accompanied by a rapid structural diversification of this primitive linear heart: looping, unidirectional circulation, an enclosed vasculature, and the conduction system.[well established][VHOG] UMLS:C0042449 MA:0000067 venous tree organ part FMA:50723 venous NCIT:C12814 venous blood vessel