Light microscopic comparison of the different staining methods on the staining of paraffin or semithin epon sections of various animal tissues

Light Microscopic Comparison of the Different Staining Methods on the Staining of Paraffin or Semithin Epon Sections of Various Animal Tissues Tissue samples received for microscopic evaluation in histology are embedded in paraffin or plastic media. Plastic semithin sections serve as a connection between light and electron microscopies. These sections are thinner than paraffin sections, and thicker than thin sections. This helps semi-thin sections in light microscopy provide more advanced details than paraffin sections do. Most plastic sections are hydrophobic, however, and cannot be stained with many stains. In this study, the aim is to develop staining methods that allow more tissue components to be differantiated in paraffin and epon sections. Various tissue samples were subjected to double fixation and epon blocking in the study. Another group of the same tissues was subjected to routine tissue processing and paraffin blocking. Toluidine blue, hematoxylin, eosin, acid fuchsin, methyl green, and neutral red stains were tested in both section groups as single stains or dual combinations. Elastic, reticular, and collagen fiber stains and mitochondrial stains were tested additionally. Three different etching agents (sodium hydroxide, periodic acid, and acetone) were applied to facilitate the penetration of stains into the epon sections. The results were evaluated under a light microscope. Acetone was found to be the most successful in removing epon. The best results in epon sections with single stains were attained with toluidine blue. Acid fuchsin and methyl green were also found satisfactory. Single stains were not successful in paraffin sections. Among the dual stainings in epon sections, toluidine blue-eosin, toluidine blue-acid fuchsin, toluidine blue-methyl green, and acid fuchsin-toluidine blue combinations yielded successful results. The best results in paraffin sections were obtained with hematoxylin-eosin. Toluidine blue-eosin and acid fuchsin-methyl green combinations were also considered useful. Four special stainings yielded good results in demonstration of elastic, reticular, and collagen fibers and mitochondria in paraffin and epon sections. It was concluded that the stainings that are found successful can be used routinely. Key Words: Semithin epon section, etching, staining, light microscopy