Small intestine villus. Fluorescence light micrograph of a cross-section through a villus from a normal human small intestine mucosa. The intestinal villi are finger-like projections which increase the surface area of the intestine, improving the efficiency of food absorption. Integrin, which can be found on the basolateral membrane of epithelial cells, and also shows up on scattered stromal cells, is stained in green. Cytokeratin, which stains epithelial cells, is shown in blue, and cell nuclei are stained in red.