Fig 022 Exocrine Glands

Salivary Glands

Salivary glands are compound tubuloalveolar glands.

The secretory cells of salivary glands are arranged in flask-like structures called acini. Acini produce the secretions, while the duct system regulates the concentration of water and electrolytes.

• Serous acini (cyan) - secrete a protein rich, watery solution. They stain well with many stains because of the vesicles of proenzymes.
• Mucous acini (green) - secrete mucus and water. They appear vacuolated due to the loss of water-soluble mucins during tissue preparation.
• Serous demilunes (cyan) - serous cells at the distal end of a mucous acinus

The secretory products are delivered to a series of ducts.

• Intralobular ducts - located within lobules:
  • Intercalated ducts (red) - drain individual acini (simple squamous or cuboidal)
  • Striated ducts (yellow) - reabsorption of water, secretes IgA and proteases (columnar)
    • Basal striations due to infoldings lined with mitochondria
• Interlobular ducts (extralobular ducts; tan) - located outside of lobules (columnar to stratified columnar)

Myoepithelial cells surround acini and contract to expel their secretions

 

Exocrine Pancreas

The exocrine pancreas is a compound tubuloacinar gland.

The secretory cells of the exocrine pancreas are arranged in flask-like structures called acini.

• Acinar cells (green) - secrete proteins (such as digestive enzymes)
• Centroacinar cells (cyan) - duct cells that appear within an acinus

The secretory products are delivered to a series of ducts which begin at the center of an acini.

• Intralobular ducts - drain individual acini
• Interlobular ducts - drain the individual lobules into the main excretory duct

There are no myoepithelial cells in the pancreas.