Abstract
Pathologic change of the round window membrane (RWM) in guinea pigs induced by the endotoxin from E. coli were observed by the electron microscopy and the effect of the endotoxin on the permeability of the RWM was examined by a tracer using horseradish perioxidase (HRP).
Twenty four hours after injection of the endotoxin (Sigma, 100 μg/ml) into the bulla, RWM invariably demonstrated inflammatory changes remniscent to those of middle ear effusion: The subepithelial space was characterized by marked edema, where a large number of neutrophils and red blood cells and a few mononuclear cells appeared. These infiltrating cells were seen often migrating in scala tympani but no definite damages to the organ of Corti present.
When exposed to HRP, these pathologic RWM demonstrated normal uptake of the tracer into the epithelial cells as well as into some of the fibrous cells of the middle layer. However, we could not confirm increase of permeability of RWM, as evaluated by the amount of intracellular uptake of the tracer.
