Stomach lining. Coloured scanning electron micrograph (SEM) of the glandular lining (mucosa) of the stomach. The gastric mucosa secretes the digestive enzymes and hydrochloric acid. This surface epithelium of simple columnar cells secretes mucus, while the gastric glands are the pits seen in this epithelium. From these pits digestive enzymes are produced. Thousands of these glands line the stomach wall. On the larger scale, the stomach mechanically churns food around, while on this scale, gastric juices act to chemically break down the food. This thick lining and large amounts of mucus protect the stomach from these digestive processes.Magnification: x800 when printed at 10cm wide.