EARLY HAIR-CELL DEGENERATION IN THE EXTREME APEX OF THE GUINEA-PIG COCHLEA

Guinea pigs, aged from 3 weeks before term to 31 weeks after birth, we re prepared for scanning electron microscopy. Examination of the extre me apex of the cochlea showed apparently pathological hair cells, even 3 weeks before term. The pathologies included loss and fusion of ster eocilia, and the formation of giant stereocilia. The pathologies were most prevalent on row 3 of outer hair cells, declining to outer hair c ell rows 2 and 1, with the inner hair cells being least affected. The abnormalities increased with time, increasing rapidly over the first f ew weeks of life, and more slowly thereafter. It is suggested that ear ly degeneration in the extreme cochlear apex forms a novel model for s pontaneous hair cell degeneration, with applicability to other types o f spontaneous hair cell degeneration.