Oesophagus epithelium. Coloured scanning electron micrograph (SEM) of the epithelium (lining) of the oesophagus. The irregularly-shaped epithelial cells (blue & yellow) have a highly folded surface. These tiny folds are called microplicae. The flattened cells form a stratified squamous epithelium many layers thick. As a muscular non-absorptive tube, the oesophagus transports swallowed food to the stomach. The microplicae keep the oesophagus moist, trap mucus to lubricate passing food and protect the epithelium from food abrasion. Magnification unknown. Credit: STEVE GSCHMEISSNER / SCIENCE PHOTO LIBRARY.