Uniform epidermal cell proliferation in the mouse tympanic membrane.

Autoradiographic studies in mice showed epidermal cell proliferation to be dispersed over the whole tympanic membrane with no specific proliferative center. This strengthens the concept that net migration of the superficial layer of the stratum corneum across the tympanic membrane is the result of random insertion of cells into a pavement-like layer of corneocytes. We also found the cell proliferation rate in tympanic epidermis to be the same as that for dorsal epidermis in both normal mouse skin and the hyperproliferative epidermis of asebia mice. There was no indication of more rapid migration in tympanic epidermis in asebia as a result of the increased proliferation rate but rather increased thickness of the tympanic epidermis. There were also unusual circular mounds of epidermal cells in all asebia tympana, apparently due to localized hyperproliferation.