part of part of has part has part contributes to morphology of vessel lymphatic vessel A network of blunt ended vessels lacking direct connection to the blood vascular system. These vessels collect and drain fluids and macromolecules from interstitial spaces throughout the animal. They derive from a subpopulation of endothelial cells and have walls that are much thinner than the blood carrying vessels. Lymphatic vessels are usually classified as either superficial or deep.[TAO] A vessel that contains or conveys lymph, that originates as an interfibrillar or intercellular cleft or space in a tissue or organ, and that if small has no distinct walls or walls composed only of endothelial cells and if large resembles a vein in structure[BTO]. A vessel that contains or conveys lymph.[AAO] AAO:0011005 BTO:0000752 CALOHA:TS-2102 EFO:0000873 EMAPA:35532 FMA:30315 MA:0000138 MAT:0000443 OpenCyc:Mx4rwA1fYZwpEbGdrcN5Y29ycA TAO:0005105 Tetrapods have evolved distinct lymphatic systems, in which lymphatic capillaries help drain most of the tissues of the body.[well established][VHOG] UBERON:0001473 UMLS:C0229889 VHOG:0001249 XAO:0000375 lymph vessel uberon vas lymphaticum lymph immune system lymph vasculature lymphatic part of lymphoid system