Microfibrillar arrays

The plant cell wall consists of cellulose microfibrils within a matrix of non-cellulosic polysaccharides, glycoproteins, and phenolics, the types and composition of which are related to the maturity and function of the cell and the plant type. Most non-ceUulosic cell wall components are held into the microfibrillar array by a combination of cross-links, including covalent and non-covalent ones [4]. 

The primary wall also contains relatively small proportions of randomly oriented, cellulosic microfibrils that have a low and non-uniform degree of polymerization (see p. 333). Miihlethaler suggested (see p. 343) that these microfibrils are synthesized by particles loosely scattered over the plasmalemma, at the beginning of formation of the cell wall. As development of the wall proceeds, the number of these particles increases until they aggregate into regular arrays this results in the production of densely packed and parallel-oriented microfibrils of the secondary wall, instead of the loose, microfibrillar framework of the primary wall. 

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