Structural abnormalities in the stria vascularis following chronic gentamicin treatment.

Freeze-fracture and thin-sectioning have been used to examine the stria vascularis of albino guinea pigs chronically treated with gentamicin. Immediately following the end of treatment, most marginal cells showed lipid bodies in the cell body region and freeze-fracture revealed alterations to the marginal cell plasma membrane. Intermediate cells also showed peculiarities including a dilation of the rough endoplasmic reticulum. A co-incidence was noted in the location in the cochlea in which effects in the stria and in outer hair cells occurred. At 4 weeks post-treatment, the stria was significantly thinner than normal and appeared less structurally complex. A minority of marginal cells degenerated. Some morphological features associated with degeneration resembled those of apoptosis, a process of controlled, cellular self-destruction. There were also indications of turnover of gap-junctions throughout the post-treatment period examined. The results indicate significant ototoxic effects of gentamicin occur in the stria and that changes to plasma membranes are one of the initial alterations.