The talent of goblet cells is to secrete mucus, a viscous fluid composed primarily of highly glycosylated proteins called mucins suspended in a solution of electrolytes. Mucus serves many functions, including protection against shear stress and chemical damage, and, especially in the respiratory tree, trapping and elimination of particulate matter and microorganisms.
Distribution and Morphology
Goblet cells are found scattered among other cells in the epithelium of many organs, especially in the intestinal and respiratory tracts. In some areas, their numbers are rather small relative to other cell types, while in tissues such as the colon, they are much more abundant.
The image below is of a villus in the small intestine of a mouse. The section was stained using the periodic acid-Schiff technique, which stains glycoproteins, including mucins, bright purple.