Which type of tissue is described as cellular covering of external and internal surfaces of the body?

Epithelial tissue is identified as the cellular covering of external and internal surfaces of the body. This type of tissue serves several essential functions, including protection, absorption, secretion, and sensation. It forms a barrier that can be found on the skin (epidermis) as well as lining various cavities and organs such as the intestines, respiratory tract, and blood vessels.

The unique structural characteristics of epithelial tissue include tightly packed cells with minimal extracellular matrix, which enhances its ability to protect underlying tissues and regulate the exchange of substances. Epithelial cells are classified by their shape—such as squamous (flat), cuboidal (cube-like), and columnar (tall)—and the number of layers they form, contributing to their diverse functions in the body.

Other types of tissues, such as nervous tissue or endothelium, serve different specific roles; nervous tissue is involved in signal transmission in the body, while endothelium refers specifically to the layer of cells lining blood vessels and lymphatic vessels. The term "cuboidal tissue" isn’t an established category within tissue types but rather refers to a shape that could be a part of epithelial tissue. Therefore, epithelial tissue is the correct choice for describing the cellular covering of both external