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 (multi–layered).
• 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

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.