Migration of human tympanic epithelium in health and disease

The gradual <i>en masse</i> migration of keratinised stratified squamous epithelium across the external surface of the human ear drum is an essential function in the maintenance of this delicate membrane by removing dead squamous epithelium to the external meatus for dispersal. The abnormal presence of the same epithelium in the middle ear space produces a proliferating, expanding mass which cannot escape from its enclosed environment. This condition, described as <i>cholesteatoma*</i>, can, in turn, invade the facial nerve, inner ear and intracranial contents and require surgical intervention which in itself poses some risk to the individual. <br></br><br></br>The probable origins of cholesteatoma have been debated for more than a century. <br></br><br></br>Two experiments are presented (1) to examine the morphology and structure of a whole, normal tympanic membrane and (2) to examine cultures of epithelium dissected from the neck of a cholesteatoma sac for differences in morphology and migration from those found in tympanic membrane epithelium, using light microscopy and time-lapse video recordings. <br></br><br></br>The results show: (1) that the epithelial and fibroblast content can be determined in different layers of the whole tympanic membrane and that the close proximity and shared polarity between epithelium on the surface of the tympanic membrane and fibroblasts in the fibrous layer did not influence the direction of epithelial migration, (2) that in tissue culture, there are (a) marked differences in the yield of epithelium from explants dissected from the neck of a cholesteatoma sac, (b) that these cultures produce epithelium with morphological differences to tympanic membrane epithelium and (c) that fibroblasts affect the fate of epithelium during tissue culture. <br></br><br></br>*cholesteatoma, first described by Cruveilhier (1829) as a pearly tumour of the temporal bone and a few years later (1838) by Johannes Muller.

Name dc:type.qualificationname

phd

Level dc:type.qualificationlevel

doctoral

Grantor dc:publisher.institution

The Open University

Year dc:date.issued

1999

Author dc:creator

• Boxall, John David

Language dc:language

en