Evaluation of Inner Ears for Loss of Sensory Cells.

Abstract : One hundred and fifty-eight temporal bones were collected from 39 pigs and 40 sheep following exposure to intense impulse noise in a hard-walled, closed environment. Thirty of these cochleas were examined using surface preparation histology and 10 were examined using the scanning electron microscope. The histological analysis showed extensive disruption of the organ of Corti in both species. The pattern of damage was typical of that observed in other mammalian species following high level impulse noise exposure. The pigs and the sheep differed in the location of the primary lesion and the extent of the damage. In addition to the inner ear changes, most middle ears that were examined showed some signs of trauma such as typmanic membrane rupture and fracture of the ossicles. This report provides a quantitative analysis of the sensory cell loss in 30 cochleas and a qualitative documentation through light and scanning electron micrographs of the traumatized surface of the organ of Corti in selected pig and sheep cochleas. Keywords: Hearing loss, Histology; Acoustics.