Last revised by Arlene Campos on 7 Jun 2024

Endolymph is one of the two types of cochlear fluids, the other being perilymph. It is located in the scala media of the cochlea.

It is secreted by the stria vascularis (also colloquially called the 'battery of the cochlea') on the outer wall of the scala media. It has a high level of potassium ions (K+) and generates a current called the endolymphatic potential, with positivity inside the scala media and negativity outside its wall (approximately 80 mV more positive than the perilymphatic compartment).

The endolymph and perilymph do not normally communicate.

NB: despite the superficial similarity in their names, the endolymph and perilymph are not related to lymph, the fluid flowing through the lymphatic system

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