[Reaction of the middle ear mucous membrane in tubal obstruction]

1. Tubal obstruction causes a rapid rise in transepithelial cytopempsis. The squamous epithelial cells show numerous vesicles carrying subepithelial fluid (extracellular fluid) to the middle ear cavity. 24 hours following tubal obstruction a widespread rupture of the epithelial junctions can be observed. Subepithelial fluid, consisting of lymphfluid, transsudate and later exsudate, enters the middle ear cavity without passing a cellular barrier. 2. Long lasting negative pressure provoces a cellular differentiation (metaplasia!) of the formerly squamous epithelium to a high, cylindric cell layer with new functions: ciliary movement and secretory activity. 3. Ablation of the tympanic membrane to expose the middle ear to air after 2-4 days, causes a stop in the epithelial differentiation but no regeneration to the normal histological flat formation. 4. Studies of samples of human middle ear mucosa in serous otitis or sero-mucous otitis show exactly the same results as during the different stages of our animal experiments.