Keratinization of middle ear cholesteatomas. II, A histochemical study of epidermal transglutaminase substrates

In both epidermal and cholesteatoma matrix tissues, the presence of acyl donors was not restricted to the sites of epidermal transglutaminase (ETgase) activity, but was almost uniformly extended throughout living layers. In reference tissues (epidermis and middle ear mucosa), residual acyl donors wee poorly detected in horny layers, while they were more abundant in the stratum corneum of the cholesteatomas studied. The presence of involucrin along the cell membrane was observed at varying distances throughout the spinous and granular layers, depending upon the epidermal and matrix configurations.