Cytokeratin patterns of normal middle ear epithelia in humans, cats, and chinchillas

We describe the cytokeratin patterns of epithelia from the tympanic orifice, tympanic cavity, and mastoid cavity of humans, cats, and chinchillas, and compare these findings with those of tracheal epithelium and external canal epidermis. Our findings are as follows: 1) middle ear epithelium from all locations demonstrates some type of cytokeratin staining, 2) broad-spectrum cytokeratin antibodies stain epithelia of middle ear cleft, tracheal epithelium, and external canal epidermis in all species, 3) specific cytokeratin antibodies reveal species-related differences in middle ear and tracheal epithelia, 4) middle ear and tracheal epithelia usually have the same pattern, and 5) none of the monospecific cytokeratin antibodies have a positive reaction with external canal epidermis. These findings suggest that the cytokeratin patterns of middle ear epithelium are useful in studying the hyperplastic and metaplastic changes in otitis media; however, caution must be exercised when making interspecies comparisons.