Effect of EDTA on cytokeratin detection in the inner ear.

Immunohistochemical studies on the epithelium of the adult inner ear are difficult to perform without decalcification of the bony capsule. In this study, we examined the effect of decalcifying agents on the immunoreactivity of various cytokeratin antigens in the cochlear duct epithelium of 2-day-old rats, allowing the comparison of fresh and decalcified specimens. Decalcification of unfixed tissue in a solution containing EDTA or EGTA and polyvinylpyrrolidone, at pH 7.4 and 4 degrees C for a maximum period of 2 days, not only preserved the antigen epitopes but even enhanced the staining intensities in comparison with fresh specimens. This enhancement effect, caused by chelating agents and found to be blocked by prior fixation with acetone, is suggested to be caused by unmasking of the antigenic epitopes.