Immunohistochemical study of cell proliferation using BrdU labelling on tympanic membrane, external auditory canal and induced cholesteatoma in Mongolian gerbils

The Mongolian gerbil is a well-known animal model for induction of aural ch olesteatomas. This animal model is useful for studying changes in the kerat inizing epithelium it is not known whether keratin accumulation can increas e the proliferative activity of the keratinizing epithelium in tympanic mem brane and meatal skin. In this study, we investigated the proliferative act ivity of the epidermis in induced aural cholesteatoma at various stages and in different areas of the tympanic membrane and meatal skin in normal gerb ils. Anti-5-bromo-2- deoxyuridine (BrdU) was injected intraperitoneally ro detect the proliferative activity of keratinizing epithelium. Immunohistoch emistry with monoclonal BrdU antibody in the normal gerbil showed intense i mmunolabelled keratinocytes at the handle of malleus, and the superior part s of pars tensa and pars flaccida. Also, mitotic activity in the deep meata l skin was more active than in the lateral meatal skin. The induced aural c holesteatoma showed more active proliferation centre of the epithelial cell than eardrum and external ear canal of the normal gerbil. These observatio ns suggest that the accumulation of the keratin debris might induce changes of the cellular proliferation in the external auditory meatus.