This tissue covers the entire surface of the human body. The cells that make up this tissue are closely packed together and they range in one or more layers. The epithelial tissue is created to form the covering of all external and internal body surfaces. There are almost no intercellular spaces in epithelial cells and there are only a very few amount of intercellular substance. This tissue is usually separated from its underlying tissue by a slim sheet of connective tissue that is known as the basement membrane. This membrane provides structural support for the epithelium and it also binds the epithelium to neighboring structures.