The mucoperiosteum of the middle ear in experimentally induced sterile otitis media.

The effect of Eustachian tube obstruction has been studied in germ-free rats. This model proved to be a reliable approach by which to study the isolated effect of tubal occlusion without the interference of infection. The effects on the middle ear structures are characterized mainly by stratification and hyperplasia of the epithelium, a transient increase in the periosteal activity, tympanosclerotic-like changes and accumulation of cholesterol in the middle ear fluid. No increase in the number of secretory elements could be registered during an observation period of 2 years.