Which of the following structures contains endolymph?

The cochlea of the inner ear is a coiled structure filled with endolymph and perilymph. Within it are three longitudinal compaments. The membranous labyrinth within the cochlea is called the scala media, or cochlear duct. This compament contains the hair receptors and is filled with endolymph that is secreted by the stria vascularis. The composition of endolymph resembles intracellular fluid (K+> Na+). The two perilymph-filled compaments, the scala tympani and the scala vestibuli surround the cochlear duct. This space is continuous with subarachnoid space, and therefore the perilymph closely resembles cerebrospinal fluid. The helicotrema is the apical connection between the scala tympani and scala vestibuli. The spiral ganglion is located in the modiolus (the cochlear pa of the body labyrinth), and contains the cell bodies of the bipolar cells that comprise the cochlear division of the eighth nerve.