Villus of the small intestine (human), animated coloured transmission electron micrograph (TEM). Cross section of the microvilli on the surface of an intestinal columnar epithelial cell. The small intestine is the part of the gastrointestinal tract between the stomach and the large intestine. It is where most of the digestion and absorption of food takes place, via the villi, which increase its surface area. The villi have an outer epithelial cell layer (columnar epithelial cells) that possess many tiny microvilli. Microvilli are tiny finger-like projections, which increase the surface area available for absorption of nutrients such as lipids, proteins and fat-soluble vitamins. The microvilli have a rapid turnover of 3-4 days. Magnification: x11, 265 when shortest axis printed at 25 millimetres.