These fibrils are attached to each other by hemicelluloses and amorphous polymers of different sugars as well as other polymers such as pectin and covered by lignin. The cellulose microfibrils which are present in the hemicellulose-lignin matrix are often associated in the form of bundles or macrofibrils. The molecules of individual microfibrils in crystalline cellulose are packed so tightly that not only enzymes but
even small molecules like water cannot enter the complex framework. Some parts of the microfibrils have a less ordered, noncrystalline structure referred to as amorphous region