Nasopharynx surface, animated coloured scanning electron micrograph (SEM). Shown hear are tiny microvilli on the surface of a squamous nasal epithelial cell. The nasopharynx (nasal part of the pharynx) lies behind the nose and above the level of the soft palate. Stratified squamous nasal epithelial cells line the surface of the nasopharynx. The epithelial cell surfaces are covered with tiny microvilli that increase the cell surface area. The microvilli likely aid in localization of foreign debris (coming from the nose) and detection by immune cells. Mucus, secreted by cells in the epithelial lining (not seen), traps foreign objects, such as bacteria, preventing them from entering the lungs. Other sensory cells and features (not seen) also occur in the nasal epithelial layer. Magnification: x8, 000 when shortest axis printed at 25 millimetres.