The scala media (cochlear duct) contains endolymph. Which cells primarily produce endolymph?

• A Hair cells of the organ of Corti
• B Cells of the spiral ligament
• C Stria vascularis cells ✓
• D Vestibular dark cells

Explanation

Endolymph, which is unique in being a high-potassium extracellular fluid (similar to intracellular fluid), is produced primarily by the stria vascularis — the highly vascularised lateral wall of the cochlear duct. It contains Na/K-ATPase pumps that actively transport potassium into the scala media, generating the endocochlear potential (+80 mV). Spiral ligament fibrocytes and vestibular dark cells also contribute but the stria vascularis is the primary producer.

Reference: Dhingra Diseases of Ear, Nose and Throat, 7th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.