[2] The perilymph in the bony labyrinth serves as connection to the cerebrospinal fluid of the subarachnoid space via the perilymphatic duct.

[3] Perilymph and endolymph have unique ionic compositions suited to their functions in regulating electrochemical impulses of hair cells necessary for hearing.

Endolymph is the fluid contained within the scala media of the membranous labyrinth of the inner ear and within the semicircular canals of the vestibular apparatus; endolymph resembles intracellular fluid in composition (potassium is the main cation).

Apart from the importance in the electric cochlear potential, the perilymph also contains a large number of proteins, e.g. extracellular enzymes and immunoglobulins.

[6] It has also been suggested that perilymph and endolymph participate in a unidirectional flow that is interrupted in Ménière's disease.