Age-related epithelial migration on the tympanic membrane of the Mongolian gerbil.

Epithelial migration on the tympanic membrane of young and aged gerbils was studied; Sudan black B was used as a marker dye. The epithelial migration center was found at the region of umbo, manubrium, and the short process of the malleus. The epithelial migration rates of the gerbils aged 3 to 6 months, 9 to 12 months, and 24 to 30 months were approximately 116, 113, and 86 micron per day, respectively. These findings suggest that the low epithelial migration rate on the tympanic membrane and external ear canal might play an important role on the high occurrence rate of external ear keratosis that results from accumulation of keratin debris in the aged gerbil ears.