Thickness of the migratory epithelium of the external auditory canal.

The migratory epithelium of the external ear has been the object of much study, and it has long been presumed to thicken in abnormal conditions of the external ear. In this study, normal values have been established for the thickness of the epithelium at various sites on horizontally sectioned normal temporal bones. Three sites, the umbo, the anterior annulus, and the posterior annulus are shown to have statistically significant thickening when compared with other contiguous sites on the same section. A study of temporal bones with various abnormalities of both external and middle ear showed a statistically significant thickening of the epithelium when compared with the normal bones. This difference was particularly marked at the umbo, anterior annulus, and posterior annulus. This would imply that these thickened areas may represent growth centers in the epithelium of the external ear.