Trachea and salivary gland. Scanning electron micrograph (SEM) of the trachea and underlying salivary gland. The trachea (top) links the larynx to the lungs. The lining consists of mucus-secreting goblet cells (single cell far right) and epithelial cells that are covered in hair-like cilia. Mucus traps debris, such as dust particles or bacteria, in the inhaled air, while the beating of the cilia moves the mucus and particles upwards out of the respiratory tract. This helps to keep the lungs and airways clear and prevent infection. The salivary gland, shows numerous serous secretory granules (small, spherical), within the serous glands. Serous glands contain serous acini, a grouping of serous cells that secrete a fluid (saliva) containing enzymes such as alpha amylase. Magnification: x1000 when printed at 10cm bacteria