With careful preservation of the capillary blood supply and by direct visualization of the cells and spaces of the organ of Corti, electrolyte-filled glass micro-electrodes are passed through the structures while the following are recorded: the dc resting potentials, ac potentials generated in response to a 200-Hz microvibrator vibrating either the stapes or basilar membrane directly, and tissue-electrode impedance at 2S0 Hz. The electrode paths are verified visually followed by surface preparation and scanning electronmicroscopy. So far, electrophoretically injected dyes have been too diffuse to be useful for this purpose. It is observed that the fluid spaces of the organ of Corti, including the subtectorial space and inner sulcus, are at, or only slightly more negative than, the potential of the, scala tympani perilymph and that all of the observed large negative potentials are intracellular. The tectorial membrane also is at the same potential as the organ of Corti spaces and the perilymph. The membrane is easily dislodged from its attachment allowing endolymph to cover the hair cells and fill the internal sulcus. When the stapes is vibrated at 200 Hz the vibration of the basilar membrane is such that the generated ac potentials are radiated from the organ of Corti in the apical region of the cochlea and are recorded maximally in the endolymph of the scala media by the micro-electrode in the basal hook region. When the basilar membrane is vibrated at 200 Hz in the region of electrode placement, the electrode records the largest ac response at the basilar membrane and at the tectorial membrane-endolymph and at the Claudius’ cell-endolymph interfaces. Impedance measures made simultaneously with the ac and dc measures indicate that the regions of different potentials observed are not the results of changing tissue-electrode impedance. A unique observation is that there is a marked impedance increase as the electrode passes through the area of Claudius’ cells. Boettcher's cells may be responsible.
ASJC Scopus subject areas
- Arts and Humanities (miscellaneous)
- Acoustics and Ultrasonics