Where is endolymph primarily produced?

Endolymph is primarily produced in the cochlea, which is a spiral-shaped structure within the inner ear responsible for converting sound vibrations into neural signals. The cochlea contains specific cells called stria vascularis that are crucial for the production of endolymph. This type of fluid is essential for maintaining the electrochemical gradients needed for the functioning of hair cells, which are key to the auditory transduction process.

The endolymph's role includes filling the scala media, the middle chamber of the cochlea, where the hair cells reside. It has a unique ionic composition, primarily being rich in potassium ions, which is vital for depolarization of hair cells when they detect sound. Thus, the cochlea’s ability to produce endolymph directly supports the auditory mechanism, making it the correct answer.