Morphological Relationship between the Tectorial Membrane and the Organ of Corti—Scanning and Transmission Electron Microscopy

The exact mechanism involved in initiating action potential in the cochlea is not yet clearly understood. It is generally believed that the wave motion of the basilar membrane causes displacement of the organ of Corti which shears against the tectorial membrane. Since the tectorial membrane and the organ of Corti should share the same shearing motion, their fixed relationship to each other becomes increasingly important. This report shows that: (1) The tectorial membrane is attached to the organ of Corti at the level of the Hensen-Deiter junction and inner phalangeal-inner border cell junction areas. The attachments are not continuous but interrupted as the trabeculae. (2) Only the tallest rows of the sensory hairs of the outer hair cells are solidly attached to the tectorial membrane, whereas the sensory hairs of the inner hair cells did not show any evidence of strong attachment as did the outer hair cells. Physiological implications of this finding will be discussed. [Supported in part by an Air Force contract from WPAB and by the Deafness Research Foundation.]