Abstract: Objective To explore the damage of sprial ganglion cell inner ear after 60Co irradiation. Methods Forty guinea pigs were randomly divided into 5 groups．The right ear was radiation ear,the left ear was controll ear.The guinea pigs were sacrificed in 1、4、7、14 and 30 days after irradiation，All specimens were dehydrated,embeded in paraffin and serially cutted into 5 m slices. Sections were stained with haematoxylin and eosin and immunohistochemistry for light microscopic examination.Results It was observed that irradiation ear promoted degeneration in spiral ganglion cells at these times(p<0.01).There was a singnificant difference on radiation-induced optical density value of caspase-3 in spiral ganglion(p<0.01).Conclusions irradiation might cause spiral ganglion cell damage. Caspase-3 cascade might be involved in the course of cell damage.

Key words: irradiation, spiral ganglion, caspase-3, inner ear