Caption

Small intestine villus, fluorescence deconvolution micrograph. Fluorescent dyes have been used to highlight cellular structures and proteins: cell nuclei (blue), g-actin (red), f-actin (green). Villi are the functional structures lining the walls of the intestines. The microvilli, the very small filamentous structures that cover the surface of a villus, are seen here (green outer layer). It is the microvilli that absorb nutrients from digested food. Actin, a protein that is a major part of a cell's cytoskeleton, has two main forms: globular actin (g-actin) and filamentous actin (f-actin). The cell nuclei seen here are part of the columnar epithelium that forms the shape of a villus. This tissue sample is from the illeum section of the small intestine.