Sequelae of experimental tympanic and inferior canal wall perforations: the double meaning of epithelial migration.

The term "epithelial migration" has been used to describe both the normal surface movement of the tympanic epithelium and the movement of epithelial basal cells in repair processes. In an attempt to distinguish between these two processes and to determine their role in the repair of a wounded tympanic membrane, 20 guinea pig tympanic membranes were perforated inferiorly and tattooed with ink through an external incision. Sequential histology of whole temporal bones at intervals from the time of injury up to three weeks showed evidence of movement of the superficial layers of epidermis which was effective in the clearance of cellular debris but not in the closure of the perforation. Drum closure was effected more by the accumulation of exudate and epithelial hyperplasia. The migration of the epithelial basal cells was slow when compared to surface movement. It is suggested that tympanic epithelial surface movement is best described by a passive term such as "epithelial displacement" and that the term migration should be restricted to the activities of the living layers of epidermis.