A study of the nerve endings of the outer hair cells in the organ of Corti--using scanning electron microscopy.

The nerve endings on the outer hair cells of the guinea pig organ of Corti were studied using a scanning electron microscope. The nerve endings in the basal turn were entirely exposed in the space of Nuel, whereas in the upper turns almost all nerve endings were covered by the Deiters' cell bulge. The number and the size of the nerve endings gradually decreased from the basal turn toward the apical turn. The shape of the nerve endings was spindle-shaped in the basal turn, while it was round in the upper turn. Some nerve endings were found to locate close to the outer hair cell surface. No pathological change was observed in the nerve endings 25 hr after completion of series treatments of streptomycin or kanamycin. However, the outer hair cells consistently showed shrinkage, especially in the basal turn.