A procedure was described for demonstrating acidic polysaccharides in formalin-fixed paraffin-embedded tissue sections using fluorescein-labelled Aspergillus polysaccharide. This material is a basic polysaccharide composed of units of galactosamine and N-acetyl galactosamine and is synthesized by the mold Aspergillus parasiticus.
The distribution of acidic polysaccharides shown by the fluorescein-labelled Aspergillus polysaccharide method was similar to results with the alcian blue-periodic acid Schiff sequence and to those with fluorescein labelled deacetylated chitin. Both epithelial and connective tissue mucins were demonstrated by the fluorescein-labelled basic polysaccharide.
Aspergillus polysaccharide may be considered a colorless polyvalent cation that acts as a carrier for the fluorochrome in this procedure. Since it can react with many types of biological cells as well as with various substances isolated from cells, it may have other important applications in histochemistry and cytochemistry.
