What is Duct?
In [[anatomy]] and [[physiology]], a '''duct''' is a tube leading from an [[exocrine gland]] or [[Organ (anatomy)|organ]]. It usually carries the gland's product to where it is used. An example is the [[vas deferens]], which carries [[sperm]] to the [[ejaculation|ejaculatory]] ducts. Another example is [[tear]] ducts, which carry tears to the eye. Ducts are lined by pavement-type [[endothelium|endothelial]] cells. Outside the endothelium in blood and lymphatic vessels is a layer with no cells called the basement membrane. Outside that are the [[smooth muscle]] cells. The smooth muscle squeezes the contents along. {{-}} {{biology-stub}} [[Category:Glands]]