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microfibril

basic structural unit of the plant cell wall, made of cellulose in higher plants and most algae, chitin in some fungi and mannan or xylan in a few algae. Higher plant microfibrils are about 10nm in diameter and extremely long in relation to their width. The cellulose molecules are oriented parallel to the long axis of the microfibril in a paracrystalline array, which provides great tensile strength. The microfibrils are held in place by the wall matrix and their orientation is closely controlled by the protoplast.