Pigment anomaly-associated inner ear deafness.

In order to investigate the pathogenesis of pigment anomaly-associated hereditary deafness, we studied black-eyed white mutant mice, which become severely deaf in early life and lacked neural crest-derived melanocytes. In the inner ear, the primary alteration appears to be located in the stria, which remains much thinner than normal and lacks intermediate cells. Melanocytes are identified with the histochemical Dopa reaction. This reaction is positive in intermediate stria cells in many animals of different ages, proving that they are derived from melanocytes. No tyrosinase-positive reactions were found in the mutant mice. This clearly indicates that the lack of intermediate stria cells is the crucial factor in the pathogenesis of pigment anomaly-associated inner ear deafness.