The cochlear duct is almost as complex on its own as the ear itself. The cochlear duct is bounded on three sides by the basilar membrane, the stria vascularis, and Reissner's membrane. Stria vascularis is a rich bed of capillaries and secretory cells; Reissner's membrane is a thin membrane that separates endolymph from perilymph; and the basilar membrane is a mechanically somewhat stiff membrane, supporting the receptor organ for hearing, the organ of Corti, and determines the mechanical wave propagation properties of the cochlear system.