Otitis media with effusion is due to negative pressure in middle ear cavity caused by dysfunction of the eustachian tube and it is well known fact that the resultant negative pressure induces various changes in the middle ear mucosa and effusion. However, studies on changes of the tympanic membrane in otitis media with effusion in detail are still rare.
The author had induced otitis media with effusion in rabbits experimentally by tubal occlusion, and had observed the histopathological changes in epidermal layer, lamina propria, and mucosal layer of the tympanic membrane with light and electron microscope during the course of time, and reached the following results.
1. The tympanic membrane in normal rabbits showed averages 65 pm in thickness, and it had become thicker to 147.7 .m at the 56th day of tubal occlusion.
2. Of all the changes of 3 layers, the epithelial hyperplasia of epithelial layer was.the first sign of histopathological changes, and regular arrangement of lamina propria was progressively disturbed, and appearance of goblet cells and submucosal inflammatory reaction of mucosal layer were most prominent a 14th and 28th day of the tubal occlusion, then slowly regressed.
3. In lamina propria, the fine and regular arrangement of fibers became irregular at 14th day after tubal occlusion, there-after the fibers were progressively degenerated with atrophy, disruption and dissociation.
4. In the changes of fibers, the circular fibers were more early affected than radial fibers after tubal occlusion.
5. There was no evidence of regeneration of disturbed fibers.
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