Possible precursors of regenerated hair cells in the avian cochlea following acoustic trauma.

Hair cell regeneration following acoustic trauma to the avian cochlea has been documented using DNA labeling with tritiated thymidine. The goal of this study was to identify potential precursor cell populations for regenerating hair cells. Chicks were exposed in pairs to a 1500 Hz pure tone at 120 dBSPL for 18 h. The animals received repeated injections of 3H-thymidine over a survival period of 6, 15, or 24 h, 3 days or 30 days after the completion of noise exposure. One cochlea from each animal was processed for autoradiography and the other for scanning electron microscopy. Labeled, regenerated hair cells were present by 3 days after exposure and recovery from injury was nearly complete by 30 days. Examination of animals in short survival groups suggest that two precursor populations may exist. For inferior sensory epithelial damage, cuboidal or hyaline epithelial cells appear to serve as the precursor cell population for the regeneration of both hair cells and supporting cells. With isolated superior damage, however, supporting cells may be the precursor population.