Although the term carbohydrate is a general concept and applies to all the
sugars and their derivatives, the name polysaccharides will be preferred as they are the
common macromolecular substrates to be recognized in microscopy. Carbohydrates
may be classified on account of their chemistry, histochemical responses in diagnostic
pathology, or distribution and function in nature [1]. Some issues are central to this
chapter: the use of bisazo dyes and fluorescent brighteners, chlorotriazines and PAS
reaction, ionic binding and metachromatic reactions. Staining and fluorescence
methods applied for histochemistry of polysaccharides have been reviewed [1-4], and
some of them, in special glycoproteins (i.e. Congo red for amyloid), will be described
in Chapter 13.11.3. More specific procedures involving the use of lectins can be found
in Chapter 4.5.2.
Keywords: Acid glycosaminoglycans, Acridines, Aryl-oxazoles, Boronic acids,
Brightening agents, Carbocyanines, Cell walls, Chloro-triazines, Congo red,
Curcumin, Lignin, PAS reaction, Ru(II)-bipyridine, Sirofluor, Trypan blue.
