小児滲出性中耳炎耳における鼓膜の組織学的観察

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The purpose of this study was to make pathohistological examination on the tympanic membrane of OME (otitis media with effusion) patients as well as to classify the degeneration of tympanic membrane lamina propria into 4 stages. Especially, observation was made on the degenerating process mainly of inner and outer fiber layers of pars tensa and of submucosal connective tissue by optical microscope and electronic microscope.
The objects of observation were the OME tympanic membrance which did not show any improvement after 3 months' preservative treatment. When the ventilation tube was inserted (and left alone) through the tympanic membrance under a general anesthesia, the tympanic membrance of size approximately 1 mm × 2 mm was taken as a sample specimen from the anterior inferior quadrant.
Control specimens were taken from the tympanic membranes of 28-week conceptus and 3-month old infant who died of sickness.
The specimens thus obtained were doublefixed by 2% glutaraldehyde solution and 1% osmium tetroxicide, and after specific dehydration with a series of ascending concentration of ethanol, they were embedded in Epon-Araldite resin and sectioned into slices.
In case of optical microscope, observation was made after executing toluidine blue dyeing to the specimens. In case of electronic microscope, uranium lead acetate dyeing, or when necessary, tannic acid dyeing was executed to the specimen. We used electronic microscope JEM 1200 EX made by Nihon Denshi (JEOL).
With the execution to toluidine blue dyeing in case of optical microscope, it was possible to clearly observe the outer and inner fiber layers. As a result of observation by optical and electronic microscope, we obtained the following conclusions.
(1) Histological degeneration in tympanic membrane of otitis media with effusion were most conspicuously observed in inner and outer fiber layers and in submucosal connective tissue.
(2) Hypertrophy of tympanic membrance of otitis media with effusion increased along with the continuation of inflammation. The reasons of it should attributable to the edema between tissues and proliferation of submucosal connective tissue resulting from the inflammation. The proliferated fibroblasts in the submucosal connective tissue were observed as to a stratified formation layers. However, inner and outer fiber layers disappeared along with the advancement of otitis media with effusion.
(3) The tympanic membrane of otitis media with effusion which was not medically treated eventually showed a state of contabescence. That is because the inner and outer fiber layers had almost completely disappeared and the submucosal connective tissues formed cicatrices.
(4) The largest factor which relates with the degeneration, destruction and disappearance of lamina propria of tympanic membrance is considered to be edema resulting from the inflammation. The edema dynamically separates and severs the fibrils which constitutes the edema itself. There is a possibility that the fluid between tissues contains collagen dissolving enzyme, which prompts the separation of the fibers.
(5) It was suggested that in the process of degeneration of fiber bundle, the finer fibrils out of two kinds of fibers which compose the fiber bundle had disappeared in the early stages, but the reason of it was not clear.
(6) It was suggested that in the degenerating process of inner and outer layers, the inner fiber layers had disappeared in the earlier stages.
(7) With sespect to the degeneration in tympanic membrance, we propose the case stage classification as follows:
Stage I: Coexistence of inner and outer fiber layers is observed.
Stage II: Outer fiber layer is observed but inner fiber layer is disappeared.
Stage III: A greater part of outer fiber layer is disappeared.
Stage IV: Both layers ire disappeared and replaced with connective tissue.