Detection of glycoconjugates by lectin gold labelling, silver enhancement, and scanning electron microscopy

A method for detecting glycoconjugates on cell surfaces in scanning electron microscopy is described. Terminal saccharides were specifically recognized by a lectin conjugated to biotin, and, after incubation with an anti-biotin antibody conjugated to colloidal gold, silver enhancement was used to produce deposits large enough to be detected in standard scanning electron microscopes. Secondary electron images revealed the ultrastructure of the tissue investigated, while backscattered electron images showed the distribution of lectin binding sites. Using digital recording and processing, the two channels were combined in colour-encoded images. The new method brings together lectin histochemistry and scanning electron microscopy and thus allows the three-dimensional distribution of glycoconjugates to be analysed at an ultrastructural level.