Light micrograph of a section of a human submandibular salivary gland, showing acini, clusters of secretory cells (pale blue). The submandibular glands are found below the lower jaw, and secrete mucus, serous fluid and amylase enzyme into the mouth to aid mastication and begin the digestion of starch into sugar. They are divided into lobules each consisting of predominately mucus-secreting units and a few serous secreting units, both of which are continuous with secretory ducts. Connective tissue (dark blue) runs between the lobules carrying blood vessels, nerves and excretory ducts. Magnification: x450 when printed at 10cm wide.