Localization of periodate-Schiff reactive glycosaminoglycans in semi-thin sections embedded in GMA-Quetol 523-MMA--application of a method for correlative light and electron microscopy of identical sites.

A correlative light and electron microscope method in which semi-thin sections of embedded tissue were treated with periodate acid and Schiff's reagent (PAS) was used to determine the precise localization of PAS reactive substance. Small blocks of tissue specimens were fixed with aldehyde mixtures. After dehydration, the blocks were embedded in a modified mixture of glycol methacrylate (GMA), Quetol 523, methyl methacrylate (MMA) and QCU-1. Semi-thin sections, 0.2-0.3 micron thick, were stained by the PAS reaction, followed by counterstaining with hematoxylin if necessary. It was found that PAS reaction products representing the specific sites for glycosaminoglycans and glycoproteins were seen in both light and electron microscopy. In the control experiments the specificity of the reaction was confirmed. The granules of goblet cells were well stained and contrasted by the reaction materials. The basement membrane and the microvilli of the epithelial cells appeared as the staining layer. In the spermatocytes the reaction products were demonstrated in the Golgi apparatus, acrosomal vesicles and head cap. The results indicated that the PAS deposits became electron dense when the embedding matrix had a low electron scattering property. Using this method of preparing semi-thin sections, a comparative study of the localization of glycosaminoglycans was performed.