This website was developed by undergraduate biology researchers working with Dr. Karen Bernd at Davidson College.

Glandular Epithelium

What are Glandular Epithelial Cells?

Glandular epithelial cells are specialized epithelial cells that secrete bodily products, sometimes called simply glands. Glands include two types: endocrine and exocrine.

A Comparison of Endocrine and Exocrine Glands:

Endocrine Glands Exocrine Glands
No duct system Ducts to release products
Secretions directed into the extracellular fluid (basal side), move into vascular system Secretions released to the apical cell surface, move out of ducts to outside environment

Exocrine glands are often the only glands associated with the term "glandular epithelium." These glands are classified by the following morphological characteristics.

Number of Cells

Unicellular Glands Multicellular Glands
Made of only one glandular epithelium cell; called intraepithelial cells Multiple cells make up one gland; called extraepithelial cells
Goblet cells are the only human example (Figure 1) Many examples, including secretory sheets in the human stomach

Figure 1. A goblet cell, in the villi of the intestine, secreting mucus.

Type of Secretion

Serous Mucous Mixed Serous-Mucous
Thin, watery protein-rich secretion Viscous secretion with lubricating or protective function Serous demilunes (cells) secrete into space between mucous cells

Where are glandular epithelial cells found? What do they do?

Glandular epithelial cells make up any glands within the body. Examples include sebaceous glands of the skin and glands in the intestinal lining (exocrine glands), and many endocrine glands releasing hormones, such as the thyroid follicle as seen below in Figure 2. The function of glandular epithelial cells is directly related to their location. Exocrine glands hold secretions for linings and coverings of the body until the secretions are needed, at which time the cells follow the above secretion mechanisms. Endocrine glands control hormone production processes, enclosing the formed hormones until they are needed in the body.

Figure 2. Representation of a thyroid follicle, which is surrounded by glandular epithelium. The follicle holds necessary components of thyoid hormones (T3 and T4) until they can be assembled and secreted from the cell as shown above.
Source: Reprinted with permission from Health Implications of Perchlorate Ingestion ©2005 by the National Academy of Sciences, Courtesy of the National Academies Press, Washington, D.C.

Mechanism of Secretion

Merocrine Apocrine Holocrine
Expelled by exocytosis Uses membrane vesicles Entire secretory cell lost, as plasma membrane breaks to release product
Only secretory product is lost Secretory product and some membrane lost Sebaceous glands use this method

Shape and Arrangement

Shapes include tubular, coiled tubular, acinar or alveolar, or a combination of these. The arrangement could be simple, branched, or compound (Figure 3).

Figure 3. A hand-drawn representation of various shapes and arrangements of glands. Glandular epithelial cells are shown by rectangular shapes, which line the exterior of the glands.

Why should Glandular Epithelial Cells be studied?

Adenocarcinoma, a malignant tumor of the glandular epithelium, accounts for 40% of all lung cancer, making it the most common type. A histological example of adenocarcinoma is shown in Figure 4.

Figure 4. Adenocarcinoma of the Lung. Glandular epithelial cells create the lining of the duct, while the cancerous cells shown in the center of the duct are malignant glandular epithelial cells.


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