Scanning electron microscopy of hair cells, stereocilia and cross-linkage systems in experimentally induced endolymphatic hydrops.

In this study scanning electron microscopy was used to examine the stereocilia and their cross-linkages in guinea pig cochleas 1, 2, 4 and 8 months after endolymphatic sac obliteration. Initial changes were restricted to the stereocilia of the outer hair cells and consisted of a disarrangement and bulging of the stereocilia with an interruption of their cross-linkage systems. Subsequently, the stereocilia became fused and atrophied. Cross-linkages of inner hair cells remained intact. Loss of both outer and inner hair cells started in the apex and progressed towards the base of the cochlea. These findings indicate that early changes in the micro-architecture of the stereocilia may have a mechanical origin, with pressure fluctuations in the scala media possibly playing an important role.