RECOVERY OF NOISE-INDUCED CHANGES IN THE DARK CELLS OF THE QUAIL TEGMENTUM VASCULOSUM

Morphologic changes in the tegmentum vasculosum (TV) of adult quail af ter high intensity sound exposure were studied. Quail were continuousl y exposed to 115 dB SPL, 1500 Hz pure tone in a sound field for 12 h a nd either sacrificed immediately (0 day), 1, 2, 3, 4, 6 or 10 days lat er. Serial sections through the basilar papilla at 100 mu m intervals from base to apex were obtained for study with light microscopy and TE M. Significant morphologic changes were found within the TV of quail s acrificed on days 0-4. On a quantitative scale, the majority of recove ry occurred within the first 24 h. After four days survival the tegmen tum appeared nearly normal. This recovery correlates well with the tem poral pattern of threshold shift recovery. These results demonstrate a temporal correlation between ultrastructural changes in the TV and fu nctional recovery of hearing after intense sound exposure. A potential etiologic role of the TV in avian temporary threshold shift is sugges ted.