The Nikon MicroscopyU confocal microscopy image gallery was created with a PCM-2000 confocal scanning system interfaced to a Nikon Eclipse E600 upright microscope. Images were recorded in successive z-axis serial sections with C-Imaging Systems software with excitation illumination provided by an argon-ion and/or a helium-neon laser.

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The submandibular gland, one of three human saliva glands, produces about two thirds of the average daily output of one liter of saliva. The saliva produced is a viscous solution containing mucin, salts and the enzyme amylase. Located in the head, below the mylohyoid muscle, this saliva gland supplies digestive secretions to the floor of the oral cavity via the submandibular duct.

The submandibular gland is composed of several different types of cells. Mucous cells are primarily full of secretory droplets of mucin (a ropy viscous fluid), pushing the flattened nuclei to the basal portions of the cells. Serous cells (80 percent of human submandibular gland cells) are shaped like pyramids with more rounded nuclei and are also pushed to the base of the cell by secretory droplets of serum-albumin (thinner, more watery). The mixed alveoli (20 percent of human submandibular gland cells) of the submandibular gland are composed of serous cells topping mucous cells and in humans, purely mucous alveoli are not common. Lined by columnar cells with apical nuclei, the striated ducts are long and very conspicuous in gland sections under the microscope. They play a role in the secretion and absorption of salts, which modify the composition of the saliva. The striations are infoldings of the basal plasma membrane with rows of elongated mitochondria in the pockets.

The parasympathetic nerve fibers from the submandibular ganglion innervate this salivary gland. As part of the autonomic nervous system, these glands secrete saliva for digestion without much thought. The saliva acts as a natural lubricant aiding the movement of the food down the digestive tract and presents some anti-bacterial properties, preventing infections.

Known as HSG cells in cell line catalogues, human submandibular gland cells are cultured with different clones selected for different characteristics. HSG cell lines are used widely in cancer, biochemistry, and genetics research.