Epithelial tissue is a type of body tissue found all over your body. It covers all body surfaces, line body cavities, and hollow organs. Moreover, it performs a wide variety of functions depending on where it’s located in your body, including protection, secretion, absorption, excretion, filtration, and diffusion. Some epithelial tissues are the following:

1. Simple cuboidal epithelium is composed entirely of cuboidal epithelial cells. As the name implies, cuboidal epithelial cells are cuboidal in shape. It is primarily responsible for secretion, absorption, and excretion. This type of tissue can be found on the surface of the ovaries, salivary glands, parts of the eye, thyroid gland, pancreas, nephron lining, and renal tubule walls.

2. Transitional epithelium comprises many layers of cells that flatten out when stretched. It serves two primary functions: a permeability barrier and regulates volume. Additionally, it lines most of your urinary tract and allows your bladder to expand.

3. Ciliated columnar epithelial cells, as the name suggests, are rectangular-shaped and have between 200 to 300 hair-like protrusions called cilia. The cilia facilitate mucus and other substances clearance in the respiratory tract via mucociliary clearance. Ciliated columnar epithelial cells are usually located in the tracheal and bronchial regions.