Opisthorchis viverrini: ultrastructure and cytochemistry of the glycocalyxof the tegument

The ultrastructure and cytochemistry of the glycocalyx of the tegument of O pisthorchis viverrini during maturation from newly excysted juvenile to adu lt stages were investigated using colloidal iron, ruthenium red and lectin stainings. The results showed that the glycocalyx was intensely stained by the first two dyes, thus indicating the presence of relatively high amounts of negative charges. However, the thickness and intensity of the staining decreased during the fluke's maturation. Binding studies using lectin probe s on the surface of adult parasites showed that binding sites for Canavalia ensiformis (Con A), Triticum vulgaris (WGA) and Ricinus communis I (RCA I) were present in relative large amounts on the glycocalyx of the adult tegu ment, whereas those for Dolichos biflorus (DBA) were relatively fewer in nu mber, and those for Ulex europaeus I (UEA I) were absent. The binding patte rns of Con A, WGA, RCA I and DBA were generally similar, and the reaction p roduct was uniformly distributed over the dorsal and ventral surfaces of th e parasite's body. These bindings, therefore, indicate the presence of D-ma nnose/D-glucose, N-acetyl-D-glucosamine/sialic acid, D-galactose and N-acet yl-D-galactosamine residues on the glycocalyx of the adult tegument.