Ototoxicity of kanamycin in albino and pigmented guinea pigs. II. A scanning electron microscopic study.

In a previous study we demonstrated an increased ototoxicity in pigmented compared with albino guinea pigs given high doses of kanamycin. In the present investigation using scanning electron microscopy we studied the fine structure of the surface preparation of the organ of Corti to examine whether a qualitative difference in lesion pattern exists between albino and pigmented guinea pigs. Kanamycin was given by daily subcutaneous injections in the amounts of 20, 60, and 200 mg per kilogram of body weight until hearing impairment was noted. No difference in the pattern of degeneration was observed in the albino and pigmented guinea pigs. No giant cilia were seen. The classic gradient of degeneration of the outer hair cells (OHCs), with the most pronounced damage in the first row of OHCs in the basal coil and progressively diminishing lesions in the second and third rows, as observed in both species.