ABSTRACT
Cellulose microfibrils, like the steel rods in reinforced concrete, are the reinforcing components in the plant cell wall. The mechan ical properties of cell walls have often been discussed in terms of cellulose characteristics. However, cellulose is generally associated with an important embedding matrix that modulates its properties similarly to the binder in concrete. The present chapter is cen tered on the supramolecular organization of cell walls. Special a t tention is given to helicoidal organization, which appears widespread from the literature of the last decade (see Refs. 1 and 2 for com plete bibliography). In fact, helicoidal walls do not constitute a unique example since numerous extracellular matrices of both animal and plant cells reveal such organization (3 ,4 ) . The strong analogy often emphasized between helicoidal constructions and cholesteric systems will be taken into account in the final discussion of the morphogenesis of cell walls.
