Intestinal microvilli. Coloured transmission electron micrograph (TEM) of microvilli (blue) on the lining of the gut. Numerous microvilli project from the surface of each simple columnar epithelial cell that lines the intestine. The cells secrete enzymes and aid in the absorption of nutrients from the intestines into the blood by providing a large surface area. Each microvillus contains 40-50 microfilaments, which run through the cytoplasm. The microfilaments contain the contractile protein actin, which suggests a primitive mobility. Magnification: x23,000 when printed 10cm wide.