Overview

• Produce and secrete saliva into the oral cavity.
• Maintain hydration and protect the oral mucosa and teeth.
• Lubricate the oral cavity during speech, mastication, and swallowing.
• Begin carbohydrate digestion through salivary amylase.
• Contribute to oral immune defense through antimicrobial components, including secretory IgA.

• Parotid Gland :

• The parotid glands are the largest majors alivary glands, located in the parotid region, anterior and inferior to the ear.
• The main parotid duct is the Stensen duct, it opens into the oral cavity opposite the uppersecond molar.
• May contain intraparenchymal lymph nodes.

• Submandibular Gland :

• The submandibular glands are also called submaxillary glands, located beneath the mandible, in the submandibular region, with a deep portion extending toward the floor of themouth.
• The main submandibular duct is the Wharton duct, it opens at the sublingual caruncle, just lateral to the lingual frenulum.

• Sublingual Gland :

• The sublingual glands are the smallest major salivary glands, located in the anterior floor of the mouth, beneath the oral mucosa.
• The main sublingual duct is the Bartholin duct, it usually drains into the submandibular duct near its terminal portion.
• Numerous small ducts of Rivinus drain directly into the floor of the mouth along the plica sublingualis.

• Microscopically, the functional structure of a salivary gland consists of secretory acini and a duct system.

Acini

• The parotid gland is almost entirely serous.
• The submandibular gland is mixed, with serous predominance.
• The sublingual gland is mixed, with mucous predominance.

• Serous Acini :

• Serous acini are usually rounded or spherical.
• They are composed of pyramidal serous cells with round nuclei, usually located basally.
• The basal cytoplasm is basophilic becauseof abundant rough endoplasmic reticulum.
• The apical cytoplasm contains eosinophilic zymogen granules.

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Slide :
Parotid gland, 6

Contribution :
© Massachusetts General Hospital Histology slide collection (MGH)

At low magnification, the parotid gland is composed of serous acini and ducts intermingled with abundant adipose tissue, separated by multiple fibrous septa.

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Slide :
Parotid gland, 6

Contribution :
© Massachusetts General Hospital Histology slide collection (MGH)

The parotid gland is composed almost entirely of serous acini. Multiple striated ducts and larger interlobular ducts are visible in this section.

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Slide :
Parotid gland, 6

Contribution :
© Massachusetts General Hospital Histology slide collection (MGH)

This section shows numerous serous acini with dark-staining cytoplasm, together with an intercalated duct characterised by a narrow lumen.

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Slide :
Parotid gland, 6

Contribution :
© UABHistologyslide box (PEIR-VM)merci.

Serous acinar cells show basally located round nuclei, basophilic basal cytoplasm, and apical secretory granules.

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Slide :
Parotid gland, 6

Contribution :
© Massachusetts General Hospital Histology slide collection (MGH)

Intercalated ducts are closely associated with the acini and are lined by simple cuboidal epithelium, with small round nuclei and scant cytoplasm.

• Mucous Acini :

• Mucous acini are usually tubular or tubuloacinar.
• They are composed of pale mucous cells with flattened nuclei displaced toward the basal part of the cell.
• The cytoplasm contains mucin-rich secretory material.

• Mixed Acini :

• Mixed acini contain both mucous cells and serous cells.
• The mucous cells usually form the main portion of the acinus.
• Serous cells may appear as crescent-shaped caps at the periphery of mucous acini.

• Myoepithelial and Basal Cells :

• Myoepithelial cells are flattened contractile cells that are difficult to identify on routine H&E staining.
• They are located between the secretory epithelial cells and the basal lamina, mainly around acini.
• Their contraction helps expel secretory products into the duct system.
• Basal cells are noncontractile cells present mainly in larger ducts, especially excretory ducts.

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Slide :
Sublingual gland, 5

Contribution :
© Massachusetts General Hospital Histology slide collection (MGH)

This section of the sublingual gland shows less prominent adipose tissue than the parotid gland, with clearly visible secretory acini.

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Slide :
Sublingual gland, 5

Contribution :
© Massachusetts General Hospital Histology slide collection (MGH)

At higher magnification, the gland shows pale mucous acini and darker serous acini. The sublingual gland is predominantly mucous, with scattered serous acini.

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Slide :
Sublingual gland, 5

Contribution :
© Massachusetts General Hospital Histology slide collection (MGH)

In mixed acini, serous cells may form crescent-shaped caps atthe periphery of mucous acini, known as serous demilunes.

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Slide :
Sublingual gland, 5

Contribution :
© Massachusetts General Hospital Histology slide collection (MGH)

The acini are surrounded by a thin layer of contractile myoepithelial cells, which help expel secretions into the ductal system.

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Slide :
Submandibular gland, 4
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Contribution :
© Massachusetts General Hospital Histology slide collection (MGH)

This section of the submandibular salivary gland shows glandular parenchyma with less adipose tissue than the parotid gland.

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Slide :
Submandibular gland, 4
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Contribution :
© Massachusetts General Hospital Histology slide collection (MGH)

The submandibular gland is a mixed seromucous gland, composed of both serous and mucous components, with predominance of serous acini.

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Slide :
Submandibular gland, 4
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Contribution :
© Massachusetts General Hospital Histology slide collection (MGH)

This section shows mucous acini capped by characteristic serous demilunes, along with adjacent intercalated duct.

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Slide :
Submandibular gland, 183-2
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Contribution :
© University of Michigan Virtual Microscopy

Mucicarmine stain highlight the mucous cells within seromucous units, demonstrating their tubular architecture, in contrast to the rounded appearance of serous acini.

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Slide :
Parotid gland, 6

Contribution :
© Massachusetts General Hospital Histology slide collection (MGH)

Striated ducts are lined by simple cuboidal to columnar epithelium and usually show a regular, rounded lumen. They receive secretions from intercalated ducts and drain into larger interlobular ducts.

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Slide :
Parotid gland, 6

Contribution :
© Massachusetts General Hospital Histology slide collection (MGH)

The epithelial cells of striated ducts show basal striations, produced by basal plasma membrane infoldings.

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Slide :
Parotid gland, 6

Contribution :
© Massachusetts General Hospital Histology slide collection (MGH)

This example shows a large-calibre interlobular duct lined by pseudostratified epithelium.

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Slide :
Parotid gland, 6

Contribution :
© Massachusetts General Hospital Histology slide collection (MGH)

Large interlobular ducts are located within dense collagenous connective tissue septa and often show a wide, irregular lumen.

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Slide :
Parotid gland, 6

Contribution :
© Massachusetts General Hospital Histology slide collection (MGH)

Large interlobular ducts are lined by tall epithelial cells with round to elongated nuclei and eosinophilic cytoplasm.

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Slide :
Sublingual gland, 185-1
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Contribution :
© University of Michigan Virtual Microscopy

This section shows the buccal squamous mucosa overlying the sublingual gland. A large excretory duct is visible and courses toward the mucosal surface.

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Slide :
Parotid gland, 6

Contribution :
© Massachusetts General Hospital Histology slide collection (MGH)

This example of the parotid gland shows thick nerve bundles and blood vessels traversing the glandular stroma.

Distinctive Features

• Parotid Gland :

• The parotid gland is composed almost entirely of serous acini.
• It often contains abundant mature adipose tissue, especially in adults.
• Large nerve bundles, including branches ofthe facial nerve, may be seen within the gland.
• Intraparenchymal lymph nodes may be present and may contain benign salivary gland inclusions.
• Occasional sebaceous cells may be observed.

• Submandibular Gland :

• The submandibular gland contains less adipose tissue than the parotid gland.
• It is a mixed seromucous gland composed mainly of serous acini, with fewer mucous acini.
• Striated ducts are usually prominent.

• Sublingual Gland :

• The sublingual gland is predominantly mucous, and serous demilunes may be seen around mucous acini.
• Intercalated ducts and striated ducts areusually short and less conspicuous than in the parotid and submandibular glands.