noun, plural: epithelial tissues
The epithelial tissue is one of the fundamental types of animal tissues (others include muscle tissue, nervous tissue, and connective tissue. It is primarily involved in protecting the underlying structures, secretion, regulation, and absorption. This tissue may be classified histologically according to the cell shape (i.e. squamous, columnar, and cuboidal) and the number of layers that make it up (i.e. simple, stratified, and pseudostratified).