Light micrograph of a section through the human intestinal wall showing it lined by finger-like projections called villi. The 'skin' of the villi is formed by short-lived columnar cells called enterocytes. Enterocytes form in crypts at the bottom of the pits between the villi, progress up their sides & are shed four days later. Their dark-stained nuclei are found at the base of the cells. Villi serve to increase the intestinal surface area for digestion. At the core of the villi & running horizontally along their base is a rich network of blood vessels where the products of digestion are absorbed & transported around the body. Magnification x35 at 35mm size. Microcosmos P.34 fig.2.36