I've searched far and wide for a solution to this problem, and I hope the experts can finally help me. Our lab performs x-gal staining on tissue sections. Prior to 6 months ago, we used Kiyota's Super Pap Pen (which put down an excellent, CLEAR barrier). Our last pen ran (mostly) dry, and we tried to order new pens from Kiyota. Apparently, their clear pens were discontinued because of toxicity, and now the only pen available from them is the Super HT Pap Pen. The new pens put down a flimsy, blue-green colored barrier. The trouble is this - when X-gal staining, some component of the stain reacts with the dye in the pap pen producing a grainy red precipitate which discolors the slide, tissue, etc. In addition, an oily reidue floats up on the solution and can stick to tissue while removing it. In a nutshell, the new pens are awful. Does anyone know of a clear pen that is still sold (EMS, zymed all seem to have colored pens), or have experience with a colored pap pen that doesn't react with xgal staining solution? Thanks

Darren Hess
MD/PhD student, Dept. of Neuroscience
University of Pennsylvania School of Medicine
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