Light micrograph of a section through an oesophagus. The oesophagus passes food from the mouth to the stomach. The oesophagus lumen (white, upper left) is lined by a layer of stratified squamous epithelium (violet). This protects underlying tissue and enables the passage of solid material by the lubricant action of its glandular secretion. Surrounding this is a supporting layer of connective tissue (pink), the lamina propria, which is rich in elastin fibres. An aggregate of lymphocyte white blood cells (purple) is seen within the connective tissue. Beneath this is are layers of circular and longitudinal muscle (red) that contract to push the food along the oesophagus. Magnification: x100 when printed at 15cm wide.