Light and electron microscopic localization of glycoconjugates with gold-labeled reagents

This paper gives an overview of the use of lectins, glycoproteins, monoclonal anti-carbohydrate antibodies, toxins, and glycosyl-transferases for the detection and localization of cellular glycoconjugates in sections from embedded tissues by light and electron microscopy. In all these techniques particles of colloidal gold were used as a marker. For light microscopic studies routine conditions of embedding such as paraffin or Epon embedding could be employed. For electron microscopic studies the low temperature embedding technique using Lowicryl K4M was found to be the method of choice for the localization of sugar residues in intracellular compartments, the extracellular matrix and the plasma membrane. The applications of the various techniques will be illustrated with data about subcellular sites of certain glycosylation steps as well as the detection of glycocalyx domain formation and cellular heterogeneity in glycoclayx composition.