Effects of acoustic trauma on corti's ganglion.

The ultrastructural features of Corti's ganglion cells were studied in guinea pigs subjected to a wide-band plain 100 dB SPL white noise (12 hr/day for 30 days). Regression was primarily observed in cells belonging to the 2nd turn and took the form of detachment of the membrane from the myelin sheath, and cytoplasmic retraction to the point of destruction of the entire cell. Intensely osmiophilic myelin bodies were frequent in Schwann cells, and in gangliar cells and their sheath. Multivesicular bodies were also common. A description of the regression noted in the myelin fibres is given. Attention is drawn to the fact that regression was not observed in sheathless fibres and cells; the latter formed about 5% of the ganglion population.