Veterinary Histology and Embryology

BASED ON THE CONSISTENCY OF THE SECRETION

• Based on the consistency of the secretion glands are classified into
  • Serous,
  • Mucous and
  • Mixed glands.
• Serous glands produce a whey-like serous secretion. Mucous gland produces a slightly more viscid fluid.
• The glands that secrete mucin, glycoprotein which when mixed with water become mucous are termed as mucous glands. Any gland that produces a mixture of serous and mucous secretions is called a mixed gland.

Serous secretory unit:

• The nucleus of a serous secretory cell is usually rounded and lies towards the base of the cell.
• At the base of the cytoplasm contains secretory granules called zymogen granules.
• Cytoplasm and Zymogen granules stain with eosin (acidophilic).

Mucous Secretory unit:

• The nuclei of the mucous secretory cells are flattened and located at the base of cells that contain them.
• There is less chromoideal substance. Above the level of the nucleus the cytoplasm contains mucin droplets, which impart a vacuolated appearance to the very light staining cytoplasm, since with ordinary staining techniques mucin is dissolved.
• Cytoplasm stains only lightly with haematoxylin.
• Mixed glands posses both mucous and serous secretory units.