False-colour transmission electron micrograph (TEM) of a section through the epithelium (lining) of the human duodenum, showing microvilli (in red), projections from the surface of epithelial cells. Microvilli are present on two specialised cell types that comprise the epithelium. One type, the goblet cells, synthesize and secrete mucus; a second cell type is adapted for absorption of food. The epithelium is arranged in finger-like projections called villi. The existence of duodenal villi and microvilli serves to maximise its secretive and absorptive capacity. Magnification: x26,000 at 6x7cm size.