Structural characterization of persistent tympanic membrane perforations in man.

In the present structural study the authors investigated the border of permanent tympanic membrane (TM) perforations in patients selected for myringoplasty. Furthermore, a panel of monoclonal antibody markers that recognize different epitopes within glycosaminoglycans as well as antibodies to epidermal growth factor and fibronectin were applied to the sections. In half of the specimens the epithelial junction ended at the inside of the perforation border, whereas in the other half it was located at the perforation border itself. In the junctional area the keratinocytes were covered by a thick keratin layer which protruded as a spur centripetally in order to bridge the perforation. Epidermal cells formed papillae and contained remnants of keratinocyte nuclei that showed similarities to those of the skin in inflammatory conditions. The connective tissue layer was fibrous and showed areas containing sclerotic plaques. The inner epithelium of the TM had abundant ciliae, thus supporting the concept that cells of the mucosal lining of the TM are able to differentiate in inflammatory conditions into ciliated cells and secretory cells. The immunoreactivity of hyaluronan and other glycosaminoglycans, the immunoreactivity of epidermal growth factor, and immunoreactivity of fibronectin, all of which are known to occur in healing wounds, were only scantily demonstrated; this could be one reason for the arrested healing and a reason why the natural drive to complete a mature closure is abandoned.