Ototoxic effect of an aminoglycoside drug on an immature inner ear.

In order to investigate to what extent an immature inner ear is injured by external causes, the effect of Kanamycin on an immature cochlea was studied in mice by using scanning and transmission electron microscopes. Our results showed that immature cochleae are more highly susceptible to injury than mature cochleae, especially when the Nuel's space and the Corti tunnel open. It is suggested that in humans, during the stage corresponding to the above period, that is, in about the third gestational month, the inner ear is highly susceptible to injury by external causes.