Ototoxity of the anticancer drug Cisplatin was studied by scanning electron microscope. Cisplatin was injected intraperitoneally to guinea pigs, and four dosage schedules were tried; (1) 9mg/Kg/day on days 1 and 8; (2) 5mg/Kg/day four times every four days; (3) 2.5mg/kg/day for 5 days, and one week after same dosage and duration; (4) 2.5mg/Kg/day for 5 days. The sacrificed group on the 5th day after the last injection (Group A) was compared with those on the 1st month after that (Group B).
The changes in the organ of Corti were apparent in the outer hair cells. But the inner hair cells were almost intact. It took the scattered pattern at the early stage of the damage of the outer hair cells, and the damage of 1st row was most severe. A lot of damage of hair cells was to be seen in basal turn and lower 2nd turn. We considered that the cochlear hair cells on Cisplatin administration had morphologically an irreversible change, because the change of the cochlear hair cells of Group A was almost equal to that of Group B. The change of stria vascularis was also visible. Vestibular system (saccule and utricle) had little change.
