Glandular Tissue
The most important glands of the oral cavity are the salivary glands. The principal salivary glands are the parotid (situated buccal to the upper molars), submandibular and sublingual, located in the floor of the mouth. There are, in addition, some minor salivary glands on the surface of the tongue, the internal surfaces of the lips and in the buccal mucosa.
Each gland is made up of lobules which resemble a bunch of grapes. The basic secretory units of salivary glands are clusters of cells called acini. These acinous epithelial cells consist of two types: serous cells, which secrete a watery fluid low in mucus, and mucous cells, producing a glycoprotein-rich (mucin) secretion. The serous cells are polyhedral in shape and produce a thin watery secretion. The mucous cells are cuboidal and produce a viscous secretion containing mucin.
When mixed, the serous cells form a cap (demilune) around the periphery of the mucous cells. The parotid glands produce a serous secretion, the submandibular glands produce a mixture of serous and mucous and the sublingual glands produce a mainly mucous secretion. Secretion is under the
control of the autonomic nervous system which controls both the volume and type of saliva produced. Saliva passes through the intercalated ducts, then the striated ducts and finally through the excretory ducts which carry the saliva to the oral cavity.
