Bifunctional reagents as vapour- and liquid-phase fixatives for immunohistochemistry.

Out of a total of eleven bifunctional reagents tested as fixatives for light microscopic immunohistochemistry, four were found satisfactory when applied in the vapour phase to freeze-dried blocks. These were diethylpyrocarbonate, as observed in earlier studies, dimethyladipimidate, p-benzoquinone, and diacetyl. Adequate but less satisfactory liquid-phase fixation was provided by three reagents (dimethyladipimidate, dimethylsuberimidate, p-benzoquinone). None of the eleven reagents gave optimal preservation of antigencity and structure when tested at the ultrastructural level. Encouraging results were obtained with p-benzoquinone, however.