Site of Action of Streptomycin Upon Inner Ear Sensory Cells

Abstract

The effects of streptomycin on the inner ear sensory epithelia were studied in guinea pigs by means of the electron microscope. The most severe damage was found in the vestibular sensory cells starting with degeneration of, and myelin figure formation in, the mitochondria. Later, swelling appeared in the sensory hairs with deformation of the cell surface, and finally disappearance of the sensory hairs, swelling of the cell surface, often with rupture and ejection of cells and cell debris into the endolymph. Nerve fibers and nerve endings were unchanged. The organ of Corti was less extensively damaged. Changes were confined to the mitochondria and stereocilia of the hair cells. The damage of the sensory cells was explained as an affection mainly of the plasma membrane of the cell and the membrane component of the mitochondria with inhibition of the formation of the rigid component of the membranes and damage to the permeability barrier.