Schematic illustration of a goblet cell in close up, illustrating different internal structures of the cell.
Transverse section of a villus, from the human intestine. X 350.
a. Basement membrane, here somewhat shrunken away from the epithelium.
c. Columnar epithelium.
d. Its striated border.
e. Goblet cells.
f. Leucocytes in epithelium.
f’. Leucocytes below epithelium.
g. Blood vessels.
h. Muscle cells cut across.
A goblet cell is a glandular simple columnar epithelial cell whose function is to secrete gel-forming mucins, which are the major components of mucus. The goblet cells use both apocrine and merocrine methods for secretion.
The majority of the cell's cytoplasm is occupied by mucinogen granules, except at the bottom, where rough endoplasmic reticulum, mitochondria, the nucleus, and other organelles are concentrated. The apical plasma membrane projects microvilli to increase surface area for secretion.
They are found scattered among the epithelial lining of organs, such as the intestinal and respiratory tracts. They are found inside the trachea, bronchus, and larger bronchioles in respiratory tract, small intestines, the colon, and conjunctiva in the upper eyelid. (Goblet cells are the chief source of tear mucus. These occur throughout the conjunctiva, especially the plica semilunaris. These are most dense in nasal conjunctiva, least dense in upper temporal fornix and absent in palpebral mucocutaneous junction and limbus.)
Goblet cells are modified simple columnar epithelial cells, having a height of four times that of their width. The cytoplasm of goblet cells tends to be displaced toward the basal end of the cell body by the large mucin granules, which accumulate near the apical surface of the cell along the Golgi apparatus, which lies between the granules and the nucleus. This gives the basal part of the cell a basophilic staining because of nucleic acids within the nucleus and rough endoplasmic reticulum staining with hematoxylin. Mucin within the granules stains pale in routine histology sections, primarly because these carbohydrate-rich proteins are washed out in the preparation of microscopy samples. However, they stain easily with the PAS staining method, which colours them magenta.
In mucicarmine stains, deep red mucin is found within goblet cell bodies. Goblet cells can be seen in the examples below as the larger, more pale cells.
The main role of goblet cells is to secrete mucus in order to protect the mucous membranes where they are found. Goblet cells accomplish this by secreting mucins, large glycoproteins formed mostly by carbohydrates. The gel-like properties of mucins are given by its glycans (bound carbohydrates) attracting relatively large quantities of water. On the inner surface of the human intestine, it forms a 200 µm thick layer (less in other animals) that lubricates and protects the wall of the organ. Distinct forms of mucin are produced in different organs: while MUC2 is prevalent in the intestine, MUC5AC and MUC5B are the main forms found in the human airway. Mucins are stored in granules inside the goblet cells before being released to the lumen of the organ.
Types of secretion
- Basal secretions. This is the normal base level secretion of mucus, which is accomplished by cytoskeletal movement of secretory granules.
- Stimulated secretion. Secretion may be stimulated by irritants such as dust and smoke, especially in the airway. Other stimuli are microbes such as viruses and bacteria.
Role in oral tolerance
Oral tolerance is the process by which the immune system is prevented from responding to antigen derived from food products, as peptides from food may pass into the bloodstream via the gut, which would in theory lead to an immune response. A paper published in Nature in 2012 has shed some light on the process and implicated goblet cells as having a role in the process. It was known that CD103-expressing dendritic cells of the lamina propria had a role to play in the induction of oral tolerance (potentially by inducing the differentiation of regulatory T cells), and this paper suggests that the goblet cells act to preferentially deliver antigen to these CD103+ dendritic cells.
- Goblet cell carcinoid - a tumor that has a component that is similar to goblet cells
The term goblet refers to these cells' goblet-like shape. The apical portion is shaped like a cup, as it is distended by abundant mucinogen granules; its basal portion is shaped like a stem, as it is narrow for lack of these granules.
- "goblet cell" at Dorland's Medical Dictionary
- Ross M, Pawlina W (2011). Histology: A Text and Atlas (6th ed.). Lippincott Williams & Wilkins. p. 592–593. ISBN 978-0-7817-7200-6.
- Young B, Woodford P, O'Dowd G (2013). Wheater's Functional Histology: A Text and Colour Atlas (6th ed.). Elsevier. p. 94. ISBN 978-0702047473.
- Johansson ME, Sjövall H, Hansson GC (2013). "The gastrointestinal mucus system in health and disease". Nature Reviews. Gastroenterology & Hepatology 10 (6): 352–361. doi:10.1038/nrgastro.2013.35. PMC 3758667. PMID 23478383.
- Johansson ME, Hansson GC (2013). "Mucus and the Goblet Cell". Digestive Diseases 31: 305–309. doi:10.1159/000354683. PMC 4282926. PMID 24246979.
- Rubin BK (2013). "Secretion properties, clearance, and therapy in airway disease.". Translational respiratory medicine 2 (6). doi:10.1186/2213-0802-2-6. PMC 4215824. PMID 25505698.
- McDole et al. (2012). "Goblet cells deliver luminal antigen to CD103+ dendritic cells in the small intestine". Nature 483 (7389): 345–349. doi:10.1038/nature10863. PMC 3313460. PMID 22422267.
- Histology image:11303loa from Vaughan, Deborah (2002). A Learning System in Histology: CD-ROM and Guide. Oxford University Press. ISBN 978-0195151732. - Digestive System: Alimentary Canal: fundic stomach, gastric glands, lumen"