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KMID : 0352519950320030375
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Korea Univercity Medical Journal
1995 Volume.32 No. 3 p.375 ~ p.391
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The Role of Collagen Fibers in Experimental Cholesteatoma
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Lee Hea-Won
Jung Hak-Hyun
Choi Jong-Ouck
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Abstract
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The origin of cholesteatoma has long been the subject of discussion and debate.
Both mtratympanic injection of chemial agents into rodents, middle ear and canal ligation of Mongolian gerbils have been reported as the useful methods to produce experimental cholesteateatomas. Propylene glycol placed in the middle ear produces chronic inflammation resulting in the epithelial hyperplasia of tympanic membrane and/or perforaion of tympanic membrane so that cholesteatomas may be induced.
Keratin debris by the ligation of external auditory canal of Mongolian gerbils displaces the tympanic membrane medially and eventually produces cholesteatomas.
The purpose of this study was to investigate the morphology of the collagen fibers of the tympanic membrane in experimentally induced cholesteatomas.
After the middle ear injection of propylene glycol in guinea pigs or ligation of external auditory canals in Mongolian gerbils, the morphologic changes of the tympanic membranes were observed by the light microscopy and transmission electron microscopy.
In guinea pigs. the collagen fibers increased in thickness after the instillation of propylene glycol. Epithelial migration through the degenerative collagen fibers was noticed at the second and third week, but collagen bundles adhered as inflammation was subsiding. In Mongolian gerbils, external pressure on tympanic membrane induced the increased thickness of collagen fibers. but focal area showed the spontaneous rupture of the tympanic membrane resulting in the middle ear inflammation. The tympanic membrane adhered to the cochlea with preserved collagen fibers, but migrated tympanic membranes showed defective collagen fibers.
Therefore, the results of the study suggest that middle ear inflammation or keratin debris on the tympanic membrane gradually increased the thickness of collagen fibers, which prevented the further epithelial invasion ; severe focal inflammation produced the degenerative changes of collagen fibers with eventual tympanic membrane perforation, which induced epithelial invasion to lead to cholesteatoma.
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