Experimental neurology
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Experimental neurology · Jan 1992
Video-enhanced DIC images of the noise-damaged and regenerated chick tectorial membrane.
Exposure of the chick cochlea to acoustic overstimulation results in a loss of hair cells and a disruption of the tectorial membrane. With time, new hair cells are produced to replace those that are lost and, concurrently, a new tectorial membrane is regenerated. Previous studies of tectorial membrane regeneration examined tissues that were fixed and processed for scanning and transmission electron microscopy. ⋯ Examination of the unfixed membrane immediately after noise exposure shows that the damage to the tectorial membrane is actually caused by the acoustic trauma and is not an artifact of fixation. After 14 days of recovery, a thick, honeycomb of new matrix has grown from the supporting cells in the basilar papilla and has formed new connections with the stereocilia of surviving and regenerating hair cells. Moreover, this new honeycomb has fused with the remainder of the surrounding, undamaged tectorial membrane, thus reestablishing a continuity in the structure of the membrane across both the damaged and undamaged regions of the basilar papilla.
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Experimental neurology · Jan 1992
The structural and functional aspects of hair cell regeneration in the chick as a result of exposure to intense sound.
This paper summarizes the structural and functional damage caused by intense sound exposure in neonatal chicks. Scanning electron microscopy has been used to follow the structural changes to the papilla and their subsequent repair. Pure-tone exposures produced a localized lesion consisting of tectorial membrane destruction, changes in surface organization of the papilla, and hair cell loss. ⋯ Auditory function returned to near normal levels within 3 days postexposure. The inescapable conclusion from these observations was that hair cell regeneration had little to do with the functional recovery observed during the first 3 days. Tectorial membrane regeneration and the restoration of cochlear micromechanics were combined to form a hypothesis to account for the restoration of auditory function.