Final answer:
Epithelium is a major tissue type that covers exterior surfaces of the body, line internal cavities and passageways, and forms certain glands.
Step-by-step explanation:
Epithelium is a major tissue type that refers to the sheets of cells that cover exterior surfaces of the body, line internal cavities and passageways, and form certain glands.
It acts as coverings controlling the movement of materials across the surface.