Epithelial tissues one of the several kinds of tissues in bodies of humans and some other animals. These tissues cover the body and line the channels of the body such as respiratory tract, alimentary tract, and urinary tract, that have openings outside.
The epithelial tissues are made up of three different types of cells - squamous, cuboidal and columnar. The columnar cells, like shapes of columns, are much longer than they are broad. Columnar epithelial tissues or the tissues made up of columnar cells line the stomach and intestines, and and the innermost layer of skin. A form of this type of tissues equipped with cilia also line the respiratory passage. Some columnar cells perform specialized functions like sensory reception in the nose, ears and the taste buds of the tongue. Goblet cells, which are are found between the columnar epithelial cells of the duodenum, secrete mucus.