Inoculation of herpes simplex virus type I (2×103pfu/2μl) into the cochlea of guinea pigs through the round window membrane produced viral labyrinthitis. Marked fibrosis filled the scala tympani with partial ossification. Endolymphatic hydrops with atrophy of the stria vascularis was also a common finding throughout the whole cochlea. The organ of Corti took on a strange appearance. Loss of the outer hair cells was the first step of its degeneration process. Its outer surface markedly ballooned into the cochlear duct, severing the heads of pillar cells, and the cells eventually disappeared. These hydropic changes in the organ of Corti are discussed.
