Salivary gland. Light micrograph of a section through a submandibular salivary gland highlighting mucous secretory cells. Salivary glands are located in the mouth and secrete saliva to aid fragmentation and swallowing of food. This frame shows a mixture of serous and mucous secretory gland cells. The mucous secretory cells, which secrete mucus, are densely packed with mucigen granules (blue). Serous secretory cells, which secrete proteins and a watery fluid containing inorganic ions, are stained pink. At lower centre (pale pink with white centre) is a duct which drains the saliva. Haematoxylin & eosin/Alcian blue stained. Magnification unknown.