The cochleas of 26 guinea pigs with intralabyrinthine inoculation of HVJ were investigated by electron microscopy. Among these, 8 guinea pigs received daily injections of cyclophosphamide (200-300 mg/kg) subsequent to HVJ inoculation. After varying survival period, the animals were sacrificed and their cochleas were processed for electron microscopy. Twelve out of 26 guinea pigs demonstrated viral lesions which were mainly localized in the lower basal turn. The present study also revealed that both stria vascularis and Reissner's membrane were preferentially infected by HVJ. In the former, the intermediate cells were least resistant whereas the basal cells were most resistant to HVJ infection. In the latter, the epithelial cells were less often affected than the mesothelial cells.
