Anatomy & Medical: A Layer Of Cells Which Forms The External Surface Of The Skin, Or Which Lines The Cavities Of The Digestive, Respiratory And Urogenital Organs, Serous Cavities, Inner Coats Of Blood And Lymphatic Vessels, Gland And Cavities Within The Brain. The Epithelium Of The Skin Is The Epidermis. The Epithelium Of The Digestive, Respiratory And Urogenital Organs Is Moistened By A Film Of Mucus And Is Known As The Mucous Coat. The Epithelium Lining Bloods Vessels Is Known As The Endothelium. Serous Cavities Are Lined By Epithelium Called Mesothelium