RESUMO
Histochemical stains with and without enzymatic digestions such as alpha-amylase, neuraminidase and hyaluronidase, made possible to localize and differentiate various types of glycoconjugates (GCs) in the tongue of the toad Bufo marinus. In the dorsal mucosae the covering epithelium of the filiform papillae, of the central folds and in the marginal cells of the fungiform papillae there were present large amounts of neutral GCs with little or no galactose and/or N-acetylgalactosamine and scanty carboxylic acid GCs while the superficial strata of the taste organs showed a mixture of neutral an acid GCs with a predominance of sulfated and carboxylic acid GCs. The glandular secretory cells showed neutral GCs almost exclusively with a gradient of concentrations increasing from the base to the apex being galactose or N-acetyl-galactosamine one of the component sugars. The ventral epithelium showed two types of mucous cells, one with neutral GCs and the other with neutral and acidic GCs. The connective tissue contained many mast cells showing highly acid GCs both sulfated and carboxilic with some neutral GCs. The extracellular connective matrix showed scanty neutral and acid GCs. Glycogen was present in the cytoplasm of glandular epithelial cells and of the striated muscle fibers. Additionally, the obtained results suggest the presence of a type of GC with a carboxylic acid (sialic acid) resistant to neuraminidase of Clostridium perfringens used in this study.