Light microscopic differential staining of epoxy-embedded adenohypophysis

Light microscopic histochemical methods for differential staining of adenohypophysis glandular cells were applied to Epon-embedded tissue, after prior softening of resin with saturated solution of NaOH in absolute ethanol. All investigated staining procedures, i.e. carmoisin L-orange G, PAS-orange G, PAS-range G-methyl blue, Gabe's aldehyde fuchsin-Halmi counterstain, aldehyde thionin-PAS-orange G and performic acid-alcian blue-PAS-orange G were found to give satisfactory results and tissue structure showed no signs of damage caused by the Epon-dissolving reagent. The features of light microscopic image given by plastic-embedded semithin sections: nearly 2-dimensional picture as well as the highest possible resolving power provide the opportunity for much more precise and detailed examination of adenohypophysis prepared that way, as compared with conventionally paraffin-embedded gland. Moreover, the described technique permits to establish a direct connection between light microscopic differential histochemistry of adenohypophysis and the electron microscopy by means of adjacent sections.