Intramuscular streptomycin effect on dark cells of utricle in guinea pigs.

Streptomycin has been used in the treatment of Meniere's disease for almost half a century. Clinical studies showed that streptomycin may eliminate vertigo attacks and stabilize or improve hearing in the majority of patients. Animal experiments have demonstrated severe damage to the vestibular hair cells after streptomycin treatment. This study is to observe the effect of intramuscular streptomycin on dark cells of utricle. Guinea pigs that had received intramuscular injections of streptomycin sulfate 400 mg/kg per day for 1 and 2 weeks were studied. The dark cells of utricle were observed under transmission electron microscope. The pinocytotic vesicles and rough endoplasmic reticula markedly decreased and the plasmalemma infoldings in the lower part of the cell reduced in the 1-week group. The luminal membrane of the cells bulged out on the surface. After the cell membrane ruptured, the cytoplasmic organelle moved into the endolymphatic space and the cell dissolved. The morphologic changes indicated that streptomycin damaged the cytoplasmic granules and the plasma membrane infoldings of the dark cells. These cytologic characteristics are engaged in fluid secretion. The damage of secretory function of the dark cells may reduce the volume of endolymph.