What do epithelial tissues primarily consist of?

Epithelial tissues primarily consist of layers of cells. This structure is characterized by tightly packed cells that form continuous sheets. Epithelial tissue serves several critical functions, including protection, absorption, secretion, and sensation. The arrangement into layers allows epithelial tissues to form protective barriers on body surfaces and linings of cavities, as well as to facilitate the selective exchange of materials, such as in the lining of the intestine or the respiratory tract.

In contrast to epithelial tissue, other types of tissues, such as connective tissues (which would involve cells embedded in an extracellular matrix), muscle tissues (which consist primarily of muscle fibers), and nervous tissues (which are made up of nerve cells), serve different functions in the body. Hence, the focus on the layered structure of cells is essential in identifying the unique characteristics of epithelial tissues.