The effect of experimental tubal obstruction on the middle ear. Preliminary report.

The rat was used as a model for studying the effect of tubal obstruction on the middle ear. Animals raised under conventional conditions, SPF- and germ-free animals were used. The predominant findings were: (1) Tubal occlusion causes an effusion of serous fluid into the middle ear cavity and promotes the pathological behaviour of pathogen and non-pathogen symbionts of the middle ear cavity. (2) The germ-free animal is an excellent model for studying the isolated effect of tubal obstruction without the interference of infectious disease. (3) The middle ear reacts towards tubal obstruction by a tendency to resorb and to organize the fluid by phagocytosis and fibrosis of the cavity. Transformation of the epithelium into mucus-producing cells was observed only in those animals which developed a middle ear infection after occlusion. (4) The final result shows a near-totally obliterated middle ear cavity resembling the atelectatic middle ear in humans.