Fine structure of natural polysaccharide systems

The ultrastructure of cellulose in higher plant cell walls is discussed. The primary and secondary wall is built up of a framework of microfibrils composed of smaller strands which are termed elementary fibrils. In recent years a number of models for the chain‐arrangement of the cellulose molecules have been proposed. According to one view the cellulose chains are in a folded conformation. Based on a new method which allows the determination of the chain‐arrangement in the elementary fibrils it was found that the structural carbohydrate must be aggregated into continuous, extended‐chain filaments of nearly perfect crystallinity. Freezeeten profiles suggest that the mechanism of fibrillar formation is characterized by enzyme particles attached to the plasma membrane and involved in cellulose synthesis.