Trachea epithelium. Light micrograph of a vertical section through the pseudostratified columnar epithelium from the trachea, the tube in the throat leading from the mouth to the bronchus and the lungs. Cilia are seen across the inner surface (top). These help to move mucus along the trachea from the lungs to the mouth, removing dust, cellular debris and pathogens. Below the cilia are the columnar cells of the tracheal epithelium (dark spots), with their nuclei at their bases. Below those two layers is a layer of connective tissue and blood vessels.