tube galen:Tube uberon anatomical tube duct Any hollow cylindrical anatomical structure containing a lumen through which substances are transported. not every anatomical conduit is a tube - for example, a bone foramen is an opening in the bone, and there is no distinct separate tube structure. Tubes may transport large mixed objects (for example, a bolus of food in the digestive tube) or they may transport the secretions of a single gland (for example, gland ducts) tubular UBERON:0000025 anatomical conduit