tube epithelium epithelial tube contrast with a multi-tissue tube, which has as parts both epithelium, connective tissue, possibly muscle layers Epithelial tubes transport gases, liquids and cells from one site to another and form the basic structure of many organs and tissues, with tube shape and organization varying from the single-celled excretory organ in Caenorhabditis elegans to the branching trees of the mammalian kidney and insect tracheal system. FBbt:00007474 AEO:0000114 UBERON:0003914 epithelial or endothelial tube uberon EHDAA2:0003114