cellulose /sel″yo͝olōs/ [L, cellula, little cell] , a colorless, insoluble, indigestible, transparent, solid polysaccharide that is the primary constituent of the cell walls of plants. In the diet it provides the bulk necessary for proper digestive tract functioning. Rich sources are fruits, such as apples and bananas, and legumes, bran, and green vegetables, especially celery. See also dietary fiber.
