Light micrograph of a section of a human submandibular salivary gland. 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 (upper and lower frame) each consisting of predominately mucus-secreting units and a few serous secreting units, both of which are continuous with secretory ducts. Connective tissue (blue) runs between the lobules carrying blood vessels (containing red blood cells), nerves and excretory ducts (centre right, white lumen). Magnification: x280 when printed at 10cm wide.