Glandular & Compound Epithelium

Glandular Epithelium

  • Glands are secretory structures formed by secretory epithelium.
  • Some columnar or cuboidal epithelium gets specialized for secretion and is called glandular cells.

They are of 2 types.

  1. Unicellular Glands: It consists of small isolated patches of secretory epithelium scattered in the inner lining. (E.g. Goblet cells in the intestinal mucosa.)
  2. Muticellular glands: It consists of clusters of secretory cells (Salivary glands).

Based on the mode of releasing their secretions, glands are divided into two: Endocrine and Exocrine glands.

  • Endocrine glands are ductless glands. Their secretions are released directly into blood or any other body fluids that bath the glands.
  • Exocrine glands release their products through specific ducts.

Compound Epithelium

  • Compound epithelium is composed of two or more layers of cells (multilayered).
  • It is mostly protective in function.                                               

 

  • They are found on the dry skin surfaces, moist surface off buccal cavity, pharynx, inner lining of glandular ducts and pancreatic ducts.
  • They protect the surfaces from mechanical and chemical stress.

 

Differences between Simple and Compound epithelium

Simple epitheliumCompound epithelium
  • Single layer of cells
  • Multi-layered (two or more layers)
  • All cells attached to the basal membrane
  • Only the bottom cells are attached to the basal membrane.
  • Function – secretion and absorption
  • Function – protection

Cell junctions

Adjacent cells in an epithelial tissue are held together by cell junctions. Three types of junctions are usually present.

  1. Tight junctions: Prevents leaking of substances across two cells.
  2. Adhering junctions: Cements adjacent cells to keep them together.
  3. Gap junctions: Permits the communication of adjacent cells by connecting their cytoplasm. This allows movement of ions and some small molecules across the cells.

 

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