False-colour transmission electron micrograph of a duodenal goblet cell, a modified columnar epithelial cell responsible for the synthesis & secretion of mucus. The cell is carrot-shaped and its distended cytoplasm contains numerous mucigen granules (circular objects, top), which combine with water to form mucus. The base of the cell contains an elongated nucleus (yellow). The cyto- plasm surrounding the nucleus is packed with rough endoplasmic reticulum (purple, linear structure) which synthesises the protein content of mucigen. The goblet cell is surrounded by absorptive epithelial cells (yellow), bearing microvilli (top). Mag: x2,400 at 6x7cm, x1,200 at 35mm size.