Blast injury to sensory hairs: a study in the guinea pig using scanning electron microscopy.

Guinea pigs were exposed to a blast (maximum 1.0 kg/cm2) of nitrous gas for 0.2 s through the external auditory canal. Then, they were either killed immediately, 1 day, 3 days, 1 week, 2 weeks, or 4 weeks after exposure to the blast. The morphological changes of the cochlear sensory hairs were examined by means of a scanning electron microscope. Changes in the sensory hairs of the animals exposed to the blast for 1 s were examined in the same manner. The results of these experiments show that sensory hairs of the basal and the second turns were damaged more markedly than those of the third and subsequent turns. Outer sensory hairs were damaged more than inner ones.