[Are cochlear outer hair cells the origin of otoacoustic emissions?].

Recent investigations have shown, that cochlear outer hair cells (OHCs) influence actively the micromechanics of the cochlea, beside their capability for auditory perception. A direct evidence for these energy requiring processes has been the registration of otoacoustic emissions in the external ear canal. Motile responses of isolated OHCs following various stimuli have been suggested to be the possible source of the postulated active mechanical processes. These motile events are possibly controlled by the efferent olivocochlear innervation. By means of two monoclonal antibodies, which were directed against external and internal acetylcholine (ACh) receptor epitopes, we were able to visualize ACh-receptors on OHCs. We suspect, that ACh is released into the synaptic cleft and binds to these newly observed receptors. Thereby they may influence the biomechanics of the cochlea.