You wrote: Chris, If you do not do this, consider etching your tissue to remove the surface plastic. We use 0.2% formic acid - start with less than a minute as your tissues are thin. Some labs etch using ethyl alcohol or methanol. We have success. Using the formic acid is commonly done on undecalcified bone embedded in methyl methacrylate to achieve a mild surface decalcification of the bone. This removes a few micrometers of calcium from bone in thicker slab section (ground and polished) and on thinner microtomed MMA sections. However, I don't think the acid actually dissolves/removes plastic itself. This is why acid etched plastic bone permit certain low molecular weight dyes (toludine blue, basic fuchsin, methylene blue and dye mixtures e.g. Sanderson's rapid bone stain and Shenks recipe MacNeals tertrachrome) to penetrate into the bone matrix of thicker slabs. However, etching the plastic with alcohols is a good way to soften and possibly remove some of the plastic to allow better penetration of dyes into the soft tissues. Glycol methacrylate is not removable, MMA is removable using xylene and some other solvents, and if you use an EM resin, you may have to do sodium ethoxide treatment to remove plastic. For EM resin embedded sections at 1 um or so, we uses Toluidine blue/sodium borate , pH 11, by flooding a section then heating on a hot plate, rinsing, drying and coverslippling. Most of the time, tissues embedded in GMA or MMA will stain with a toluidine blue method, particularly when the pH is 8 or higher.
There is a very good discussion on the etching, dyes, pH and temperature effects on various plastics in this publication. Horobin RW. Staining plastic sections: a review of problems, explanations, and possible solutions. J Microscopy 131:173-186, 1982. Gayle M. Callis HTL(ASCP)HT,MT Bozeman MT 59715 _______________________________________________ Histonet mailing list Histonet@lists.utsouthwestern.edu http://lists.utsouthwestern.edu/mailman/listinfo/histonet