Light micrograph of a section through a parotid salivary gland. The gland is divided into numerous lobules by connective tissue (blue). Within the lobules are serous secretory cells (pink) that secrete a fluid, saliva, that lubricates the mouth and contains enzymes that start the digestion process. Excretory ducts are white. The parotid glands are the largest of the salivary glands. In humans, the two parotid glands are just in front of either ear. Magnification: x400 when printed at 15cm tall