STRUCTURE OF INNER EAR SENSORY EPITHELIAL CELLS IN RELATION TO THEIR FUNCTIONS

The structure and reationships of the hairs of the cochlear and vesibular sensory cells have been investigated in fixed and fresh tissue by light, phase-contrast and electron microscopy. The cochlear hairs closely resemble the stereocilia of the vestibular cells, but there are differences in size, number and arrangement between those of the inner and outer hair cells. In the cuticle-free region of the cell-surfce a basal body is found, corresponding to the ingle kinocilium on each vestibular cell. The stiff cochlear stereocilia are regarded simply as levers, transmitting mechanical energy from the overlying tectorial membrane by way of the cuticular plate to the basal body. It seems unikely that their bending, as such, has the impotance generally ascribed to it. In view of the great functional significance of modified kinocilia in other sense organs, the basal body, like the vestibular kinocilium, with its associated mitochondria, membranes and granules, appears to be the essential excitable structure of the hir cells. (Author)