PRIMARY AND SECONDARY PLANT CELL WALLS: A COMPARATIVE OVERVIEW*

Light and transmission electron microscopy are used in studying wall morphology and histochemical methods, including immunocytochemistry, can be used to locate specific compounds in walls. All plant cell walls contain a fibrillar phase of cellulose microfibrils and a matrix phase which contains a high proportion of non-cellulosic polysaccharides that vary in their chemical structures, depending on wall type and plant taxon. The non-cellulosic polysaccharide compositions of three common wall types — lignified secondary walls, non-lignified secondary walls, and non-lignified primary walls — exemplify this. The principles used in constructing the most recent models of non-lignified primary walls can be used in modelling lignified secondary walls