Salivary Duct Disorders: Obstruction, Stones, And Infections

Salivary Duct Disorders: Obstruction, Stones, And Infections

Describe briefly the ductal system of a salivary gland.
Answer:

Ductal system of salivary gland:

• The ductal system of salivary glands consists of hollow tubes.
• It is a varied network of tubules that progressively increase in diameter, beginning at the secretory end pieces and extending to the oral cavity,
• Three classes of ducts are present.

1. Intercalated intralobular.
2. Striated intralobular
3. Excretory interlobular.

1. Intercalated duct:

• They are the smallest duct connecting secretory units to the striated duct.
• They are lined by a single layer of flow cuboidal cells and myoepithelial cell bodies.
• The overall diameter is smaller.
• Several ducts join to form larger intercalated ducts.
• Its length differs in major and minor salivary glands.

Ductal System of a Salivary Gland Functions:

• The intercalated ducts contributed macromolecular components stored in their secretory granules.
• Undifferentiated cells present in it may proliferate and undergo differentiation to replace damaged or dying cells.
• Allow the passage of saliva.
• Modify the saliva through the secretory and absorptive processes.

Mechanism Of Saliva Formation

2.  Striated duct:

• Forms the largest portion of the ductal system.
• Receives primary saliva from the intercalated duct.
• They are lined by tall columnar cells with large, centrally placed nuclei and eosinophilic cytoplasm.
• The overall diameter of the duct is greater than that of the secretory end pieces and intercalated ducts.
• The combination of in-foldings and mitochondria accounts for the striations.

Striated Duct Functions:

• They are sites of electrolyte reabsorption, especially of sodium and chloride, and secretion of potassium and bicarbonate.
• Their cells are involved in active reabsorption.

3. Excretory ducts:

• They are located in the connective tissue septa between the lobules of the gland.
• It contains 2 layers.
  1. The mucosa
  2. Outer connective tissue adventitia.
• They consist of pseudostratified columnar epithelium which finally merges with the epithelium of the oral cavity.
• Cells seen in the excretory duct are:
• Basal cells with tonofilaments.
• Tuft cells with microvilli.
• Cells with pale cytoplasm and dense nuclear chromatin.
• Lymphocytes and macrophages.
• Dendritic cells; antigen-presenting cells.

Excretory Ducts Functions:

• The excretory duct stretches passively and allows and accommodates varying volumes of saliva.
• Intercalated duct cells
• Striated duct cell