Lectins are biomolecules with adequate affinity and narrow range of specificity for defined sugar residues so that they can be used as selective probes for the detection of glycoconjugate glycosylation. Consequently, lectins are useful for specific saccharide staining in histology. In a similar way to immunohistological techniques, lectins are either conjugated with markers and used in direct labeling studies, or they are applied in so-called indirect staining techniques. Similarly, nucleic acids are very popular as specific probes for histological DNA/RNA stainings (in situ hybridization technique), f.e. to identify sites of gene expression, to analyze transcription, for chromosome mapping or to identify pathogens. Marker molecules including detection principles known from immunohistology play a major role in the application of cellular hybridization techniques.