Regeneration of hair cell stereociliary bundles in the chick cochlea following severe acoustic trauma.
Examination of pure-tone acoustic damage in the chick cochlea revealed a significant amount of hair cell recovery over a 10 day period following the exposure. The recovery included both a regeneration of stereociliary bundles to replace those that were lost and a reshuffling of the mosaic pattern of the hair cell surfaces that survived. Ten-day-old chicks were exposed to a 1500 Hz pure tone at 120 dB SPL for 48 h and their cochleae were processed for scanning, transmission and light microscopy at 0 h, 24 h, 48 h, 4 d, 6 d and 10 d after exposure. Immediately after exposure the damaged region exhibited two types of hair cell trauma. The first was a defined area of complete hair cell loss and the second was an area where the hair cells survived but exhibited varying amounts of stereocilia injury. After 48 h of recovery, new hair cells were identifiable in the region of hair cell loss and with time they underwent a progressive maturation of their stereociliary bundles. The surviving hair cells showed a dramatic rearrangement and expansion of their surfaces but exhibited no repair of the damaged stereociliary bundles. These results suggest that the chick cochlea is capable of a significant amount of recovery and regeneration following acoustic trauma.
Cotanche
D A
DA
Dept. of Anatomy and Cell Biology, Medical University of South Carolina, Charleston 29425.
D000818:Animals; D002645:Chickens; D002923:Cilia / Q000648:ultrastructure*; D006198:Hair Cells, Auditory / Q000473:pathology*; D006317:Hearing Loss, Noise-Induced / Q000473:pathology*; D008854:Microscopy, Electron; D009410:Nerve Degeneration; D009416:Nerve Regeneration