Salivary Glands
On this page 8 sections
Overview
| Salivary Gland | Secretion Type | Distinctive Histological Features | High-Yield MCQ Triggers |
| Parotid Gland | Purely Serous | * Dark-staining pyramidal cells with round, basal nuclei. * Highly developed intercalated and striated ducts. | * "Starch digestion / Amylase-rich". * Stensen's duct opens opposite the maxillary second molar. * Contains numerous fat cells (adipose tissue) with aging. |
| Submandibular Gland | Mixed (Predominantly serous) | * Contains both serous and mucous acini. * Features Serous Demilunes (crescent-shaped caps over mucous cells). | * Produces the highest volume of daily resting saliva (60–65%). * Wharton's duct opens at the sublingual caruncle. |
| Sublingual Gland | Mixed (Predominantly mucous) | * Lightly staining mucous cells with flattened, basal nuclei. * Poorly developed striated/intercalated ducts. | * The smallest of the three major pairs. * Bartholin's duct (main) and Ducts of Rivinus. |
| Von Ebner's Glands | Purely Serous | * Minor salivary glands located beneath the circumvallate papillae. | * "Flushes the gustatory trenches" to clear old taste molecules so new flavors can be registered. |
Ductal pathway:
1. Secretory Endpieces (Acini)
The pathway begins in the acini (which can be serous, mucous, or mixed), where the primary saliva is initially produced by the secretory cells.
2. Intercalated Ducts
Directly arising from these secretory endpieces are the intercalated ducts.
- They are lined by simple cuboidal epithelium and are surrounded by myoepithelial cells that help pump the secretion forward.
- These ducts contribute macromolecular components (like lysozyme and lactoferrin) to the saliva.
3. Striated Ducts
The intercalated ducts merge to form the striated ducts.
- These are lined by simple columnar cells characterized by highly folded basal membranes (giving a "striated" appearance under a microscope).
- They play a major role in modifying the saliva by actively reabsorbing sodium and chloride ions while secreting potassium and bicarbonate ions, turning the fluid hypotonic.
4. Interlobular (Excretory) Ducts
From the striated ducts, the saliva flows into the interlobular ducts, which run within the connective tissue septa between the lobules of the gland. As these ducts fuse and grow larger, their lining transitions from simple columnar to pseudostratified or stratified columnar epithelium.
5. Main Excretory Duct
Finally, the interlobular ducts coalesce into the main terminal excretory duct of the gland (such as Stensen's duct for the parotid gland or Wharton's duct for the submandibular gland). This main duct empties the fully modified saliva directly into the oral cavity, transitioning to stratified squamous epithelium near its opening to match the oral mucosa.
Cells
| Cell Type | Cytoplasm Appearance | Nucleus Shape & Position | Typical Arrangement / Location |
| Mucous Cells | Lightly stained, foamy, or clear (mucin washes out) | Flattened; compressed against the basal membrane | Tubular configurations |
| Serous Cells | Darkly stained, basophilic (intense purple/blue) | Round; located in the lower third of the cell | Spherical clusters called acini |
| Ductal Cells | Moderately eosinophilic (pinkish) | Round-to-oval; centrally and neatly organized | Linear rows forming tubes (cuboidal to columnar) |
| Myoepithelial Cells | Clear/difficult to see without special stains | Small, dense, and flattened | Wrapping around the outside of acini and intercalated ducts |
| Fibroblasts | Elongated, minimal cytoplasm | Spindle-shaped; flat and tapered | Scattered throughout the surrounding connective tissue septa |