SALIVARY GLANDS Parotid Gland Submandibular Gland Sublingual Gland

SALIVARY GLANDS

• • Parotid Gland. Submandibular Gland. Sublingual Gland. Others (labial, buccal, lingual and palatine glands)

Functions • Keeps mouth moist • Provide a protective and lubricant coat of mucous. • Enzymes ( amylase, lysozyme), immunoglobulin Ig. A.

• These are compound tubulo-alveolar glands. • Secretory elements may be rounded (acini), pear shaped (alveoli), tubular or a mixture of these (tubulo-acinar, tubuloalveolar). • These will lead into series of ducts through which secretions are poured into the oral cavity.

• In sections we will see large number of closely packed acini with scattered duct in between them. • Supported by connective tissue that divides the gland into lobules and form capsule around them. • Blood vessels, lymphatics and nerves run in the connective tissue.

• Cells lining the acini of salivary glands are described either as serous or mucous. • In haematoxylin and eosin staining, serous cells stain darkly (because of zymogen granulespink), rounded nuclei and endoplasmic reticulum -purple), that lies towards the base of the cell. Biphasic staining).

• Mucous cells stain lightly and therefore appears empty. They are completely filled by mucoid material that gets stained very poorly. • This pushes the nuclei towards the basement membrane. • The nucleus is flattened at the base.

• Acinus, is made up entirely of serous or mucous cells. • In some cases mucous acinus are covered by groups of serous cells that are arranged in the form of crescents or demilunesserous demilunes.

• In parotid gland, the acini are mostly serous occasionally mucous acini are also present. That’s why it is called as serous salivary gland. • In submandibular gland, some are serous and some are mucous. • The latter are capped by serous cresents (demilunes). That’s why it is called as mixed salivary gland. • In sublingual gland, mainly mucous acini, are present but few serous acini are also present. That’s why it is called as mucous salivary gland.

Parotid gland

Submandibular gland

Sublingual gland

Parotid gland

Sub lingual gland

• A gland which contain only one type of acini, either mucous or serous is said to be homocrine. • If it contain more than one than it is called as heterocrine. • All glands described above are heterocrine.

• Secretions produced in the acini pass through a system of ducts which have different structure. • Smallest ducts are called as intercalated ducts which are lined by cuboidal or flattened cells. • They open into striated ducts lined by columnar cells. They are so called because basal parts of cells show vertical striations. • They finally open into excretory ducts which are lined by simple columnar epithelium.

• Serous cells are arranged in the form of rounded acini. As a result they are roughly pyramidal in shape having a broad base (towards basement membrane) and a narrow apex (towards lumen) • -Biphasic staining. • Deep to these cells are united by tight junctions.

• Apical cytoplasm contains secretory granules-zymogen granules. • Cytoplasm also contains golgi complex, rough endoplasmic reticulum, mitochondria, lysosomes and microfilaments.

• Mucous cells are usually arranged in the form of tubular secretory elements. • Cells lining them are columnar. • Their secretory granules are large and illdefined. • Golgi complex, rough endoplasmic reticulum are present.

• In submandibular gland serous demilunes are present. • These serous cells of demilune drain into lumen of acinus through fine canaliculi passing through the interval between mucous cells.

• Myoepithelial cells are present in relation to alveoli, acini and intercalated ducts of salivary gland. They are also seen in relation to large ducts (intralobular and interlobular). • These cells lie between the epithelial cells and basement membrane.

• They are contractile, their contraction squeeze out the secretion from the alveoli or the acini into lumen of the ducts which drains into the oral cavity.

Thank u.