Immunohistochemical study of transforming growth factor-alpha expression in normal and perforated tympanic membrane.

An immunohistochemical study of transforming growth factor-alpha (TGF-alpha) distribution was carried out to clarify the mechanism responsible for accelerated epidermal cell proliferation after perforation of the rabbit tympanic membrane. In the normal tympanic membrane, TGF-alpha expression was not observed, whereas after perforation, over the whole tympanic membrane including the margin of the perforation, TGF-alpha-positive cells appeared and were scattered in the epidermal cell layer. After healing of the perforation, a marked decrease of TGF-alpha-positive cells in the tympanic membrane was observed. This finding suggests that TGF-alpha induces proliferation of epidermal cells after the perforation stimulus.