STRUCTURE OF SALIVARY GLANDS DIFFERENCE BETWEEN SEROUS amp MUCOUS ACINI DUCT SYSTEM OF SALIVARY GLANDS DUCT SYSTEM OF SALIVARY GLANDS ACINI amp SMALL DUCTS OF SALIVARY GLANDS PAROTID GLAND The parotid salivary gland is a large serous gland that is classified as a compound tubule acinar gla ID: 917558
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EXOCRINE GLANDS
HISTOLOGY
Slide2Slide3Slide4Slide5Slide6Slide7Slide8Slide9Slide10Slide11Slide12Slide13STRUCTURE OF SALIVARY GLANDS
Slide14Slide15Slide16Slide17DIFFERENCE BETWEEN SEROUS & MUCOUS ACINI
Slide18DUCT SYSTEM OF SALIVARY GLANDS
Slide19DUCT SYSTEM OF SALIVARY GLANDS
Slide20ACINI & SMALL DUCTS OF SALIVARY GLANDS
Slide21PAROTID GLAND
The parotid salivary gland is a large serous gland that is classified as a compound tubule acinar gland.
The parotid gland is surrounded by a capsule from which arise numerous interlobular connective tissue septa that subdivide the gland into lobes and lobules. Located in the connective tissue septa between the lobules are arteriole, venule, and interlobular excretory ducts.
Each salivary gland lobule contains secretory cells that form the serous acini and whose pyramid-shaped cells are arranged around a lumen. The spherical nuclei of the serous cells are located at the base of the slightly basophilic cytoplasm.
In certain sections, the lumen in serous acini is not always visible. At a higher magnification, small secretory granules are visible in the cell apices of the serous acini. The number of secretory granules in these cells varies with the functional activity of the gland.
All serous acini are surrounded by thin, contractile myoepithelial cells that are located between the basement membrane and the serous cells.
Slide22PAROTID GLAND
Slide23PAROTID GLAND
Some parotid gland lobules may contain numerous adipose cells that appear as clear oval structures surrounded by darker staining serous acini.
The secretory serous acini empty their product into narrow channels, the intercalated ducts. These ducts have small lumina, are lined by a simple squamous or low cuboidal epithelium, and are often surrounded by myoepithelial cells. The secretory product from the intercalated ducts drains into larger striated ducts.
These ducts have larger lumina and are lined by simple columnar cells that exhibit basal striations. The striations that are seen in the striated ducts are formed by deep in folding of the basal cell membrane.
The striated ducts, in turn, empty their product into the intralobular excretory ducts that are located within the lobules of the gland. These ducts join larger interlobular excretory ducts in the connective tissue septa that surround the salivary gland lobules.
The lumina of interlobular excretory ducts become progressively wider and the epithelium taller as the ducts increase in size. The epithelium of excretory ducts can increase from columnar to pseudostratified or even stratified columnar in large excretory (lobar) ducts that drain the lobes of the parotid gland.
Slide24PAROTID GLAND IN HIGH MAGNIFICATION
Specific structures represented at a higher magnification in separate boxes below.
Slide25SUBMANDIBULAR GLAND
The submandibular salivary gland is also a compound tubule acinar gland.
The submandibular gland is a mixed gland, containing both serous and mucous acini, with serous acini predominating. The presence of both serous and mucous acini distinguishes the submandibular gland from the parotid gland, which is a purely serous gland.
The serous acini are similar to those in the parotid gland. These acini are characterized by smaller, darker-stained pyramidal cells, spherical basal nuclei, and apical secretory granules.
The mucous acini are larger than the serous acini, have larger lumina, and exhibit more variation in size and shape.
The mucous cells are columnar with pale or almost colorless cytoplasm after staining. The nuclei of mucous cells are flattened and pressed against the base of the cell membrane. In mixed acini (serous and mucous), the mucous acini are normally surrounded or capped by one or more serous cells, forming a crescent-shaped serous demilunes.
Slide26SUBMANDIBULAR GLAND
Slide27SUBMANDIBULAR GLAND
The thin, contractile myoepithelial cells surround the serous and mucous acini and the intercalated ducts. The duct system of the submandibular gland is similar to that of the parotid gland.
The small intralobular intercalated ducts have small lumina and are shorter, whereas the striated ducts with distinct basal striations in the cells are longer than in the parotid gland. This figure also illustrates a mucous acinus that opens into an intercalated duct, which then joins a larger striated duct. Interlobular excretory ducts are located in the interlobular connective tissue septa that divide the gland into lobules and lobes.
Also located in the connective tissue septa are nerves, an arteriole, venule, and adipose cells.
Slide28SUBMANDIBULAR GLAND IN HIGH MAGNIFICATION
Specific structures represented at a higher magnification in separate boxes below.
Slide29SUBLINGUAL GLAND
The sublingual salivary gland is also a compound, mixed tubule acinar gland that resembles the submandibular gland because it contains both serous and mucous acini.
Most of the acini, however, are mucous that are capped with peripheral serous demilunes. The light-stained mucous acini are conspicuous in this section.
Purely serous acini are less numerous in the sublingual gland; however, the composition of each gland varies.
Slide30SUBLINGUAL GLAND
Slide31SUBLINGUAL GLAND
In comparison with other salivary glands, the duct system of the sublingual gland is somewhat different.
The intercalated ducts are short or absent, and not readily observed in a given section. In contrast, the nonstriated intralobular excretory ducts are more prevalent in the sublingual glands.
These excretory ducts are equivalent to the striated ducts of the submandibular and parotid glands but lack the extensive membrane in folding and basal striations.
The interlobular connective tissue septa are also more abundant in the sublingual than in the parotid and submandibular glands. An arteriole, venule, nerve fibers, and interlobular excretory ducts are seen in the septa.
The epithelial lining of the interlobular excretory ducts varies from low columnar in the smaller ducts to pseudostratified or stratified columnar in the larger ducts. In addition, the oval-shaped adipose cells are seen scattered in the connective tissue of the gland.
Slide32SUBLINGUAL GLANDSAt higher magnification, the contractile myoepithelial cells are seen around individual serous and mucous acini.
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