OpenStax
Open Stax: Anatomy & Physiology: Epithelial Tissue
This learning module helps students better understand epithelial tissue - essentially large sheets of cells covering all the surfaces of the body exposed to the outside world and lining the outside of organs.
McGraw Hill
Mc Graw Hill: Epithelial Tissue
The structure and function of epithelial tissues and basements membranes are explained in this concise site.
Mocomi & Anibrain Digital Technologies
Mocomi: Structure and Function of the Skin
Defines skin and its layers and also provides other interesting facts.