Small intestine villus. Coloured scanning electron micrograph (SEM) of a freeze fracture section through a villus of the intestinal lining. Villi are finger-like projections that increase the surface area of a structure. The outer surface is mostly columnar epithelium (pink), which absorbs food. Within in the epithelium are goblet cells (dark pink ovals), which secrete mucus to lubricate food and prevent self-digestion. The lamina propria or central core (orange) contains the blood supply that transports the products of digestion, individual red blood cells (red) are seen within it. Magnification: x400 at 6x7cm size.