Histopathological research on eardrum perforations.

Basic information on the healing process of tympanic membrane perforations is scarce and sometimes contradictory. So the histological and histopathological course of the closure of tympanic membrane perforations was studied in experiments on mice and hamsters. From this investigations it seems evident that traumatic tympanic membrane perforations close nearly always spontaneously in animals. This fact must be kept in mind in the evaluation of techniques and results of tympanoplasties in animal experiments. Furthermore the squamous epithelium of the eardrum plays an important role in the regeneration of tympanic perforations. The closure of the connective tissue defect has always a tendency to lay behind the healing of the epithelial layer. This mechanism differs from the normal healing process of skin wounds where the squamous epithelium migrates over a newly formed granulation tissue layer. On the basis of these findings some practical considerations can be made on tympanoplasties in human.