Where is the Epithelial tissue located?

It is more then just skin. It is without break also the internal linings. The lungs, stomuch and intestinal linings, all the way out. See the link I found in google for a really good explanation. read more

Epithelial tissue is a sheet of cells that covers a body surface or lines a body cavity. Two forms occur in the human body: Covering and lining epithelium– forms the outer layer of the skin; lines open cavities of the digestive and respiratory systems; covers the walls of organs of the closed ventral body cavity. read more

Epithelial tissue (epithelium) covers the entire outer surface of the human body and animals, lining the mucous membranes of the hollow internal organs (stomach, intestines, urinary tract, pleura, pericardium, peritoneum) and forms part of the glands of the internal secretion. read more