Photopolymerized 2-hydroxyethylmethacrylate as a mounting medium preserving immunocytochemical reaction and nuclear counterstain

Immunocytochemical or cytoenzymological techniques often make use of coupli ng reactions between a substituted naphtol and a diazonium salt. A positive reaction results in an azo dye precipitate. Unfortunately, this precipitat e is easily soluble in alcohols and organic solvents. Thus, usual mounting media are not usable and permanent preparations cannot be obtained, A stabl e mounting medium such as Apathy's syrup can be used, but nuclear counterst aining disappears in a few days. We tested the hydrophilic monomer 2-hydrox yethylmethacrylate, containing various photopolymerizing agents, as a perma nent mounting medium. 2-2 Dimethoxy 2-phenyl acetophenone proved to be the most useful photopolymerizer, The cytocentrifugation slides must be dried b efore mounting to avoid recrystallization artifacts. The azo dye precipitat e and nuclear counterstaining can be preserved perfectly long-term. The cos t of these media is very low.