Light micrograph of a longitudinal section through the epiglottis, the flap of tissue located at the top of the larynx (voice box). The surface of the epiglottis consists of squamous epithelium (red) enveloping connective tissue (bright blue) and cartilage (light blue). Within the connective tissue are mucous glands and ducts (pink) and lymph nodes (lower left, granular red structure). During swallowing the larynx moves upwards so the epiglottis folds forward to form a lid, closing it off. This prevents food going into the lungs and causing choking. Magnification: x40 when printed at 15cm wide.