A striated duct is a gland duct which connects an intercalated duct to an interlobular duct. It is characterized by the basal infoldings of its plasma membrane, characteristic of ion-pumping activity by the numerous mitochondria. Along with the intercalated ducts, they function to modify salivary fluid by secreting HCO₃^- and K⁺ and reabsorbing Na⁺ and Cl^- using the Na-K pump and the Cl-HCO₃ pump, making the saliva hypotonic.