duct
     n 1: a bodily passage or tube lined with epithelial cells and
          conveying a secretion or other substance; "the tear duct
          was obstructed"; "the alimentary canal"; "poison is
          released through a channel in the snake's fangs" [syn: {epithelial
          duct}, {canal}, {channel}]
     2: a continuous tube formed by a row of elongated cells lacking
        intervening end walls
     3: an enclosed conduit for a fluid
Source: WordNet® 2.0