Abstract
The influences of blast on auditory organs were studied experimentally with a scanning electron microscope. Guinea pigs were exposed by blast of maximum pressure 1.0kg/cm2 for 0.2sec. via the external auditory canal. Then, guinea pigs were sacrificed immediately after the blast and, 1 day, 3 days, 1 week, 2 weeks and 4 weeks after exposure. Changes of sensory hairs of inner and outer hair cells were observed with a scanning electron microscope. Furthermore, changes of sensory hairs in 1 second exposure were observed. The following results were obtained.
1. Sensory hairs were injured more in basal and second turns than in third and subsequent turns.
2. Outer sensory hairs were injured morn than inner ones but in the place where outer hairs were injured severaly, inner hairs were injured, too.
3. The sensory hairs were lost uncontinuously, and the extent of injury area was not constant.
4. The basilar membrane was more resistant than sensory hairs.
5. The perforation of tympanic membrane was seen in all cases.
6. Rupture of the round window membrane was also seen in some cases, but whether the rupture was present or not, there was not a great difference in injury of sensory hairs.
7. When pressure loading was prolonged to 1sec., the injury of sensory hairs became severer, the extent of injury became wider, and the injury often continuous from the basal to the upper turns.
