Epithelial tissues!

Epithelial tissue is located on the very outside of an organ or organism (i.e. skin) or found lining lumen (cavities in hollow organs (i.e. stomach lining). Epithelial tissue always has a free surface (no contact with another cell). Epithelial tissue is also avascular (no blood vessels) and must depend on underlying tissues for the nutrients and oxygen it needs to maintain homeostasis. For this reason, epithelial tissue is usually very thin. Another characteristic of epithelial tissue is that it has little to no inter cellular matrix between it's cells. The cells are tightly packed together. Major functions of epithelial tissue include, protection, secretion, and absorption.

    Squamous.


   Simple Squamous.

   Stratified Squamous.

  Simple Cuboidal.

   Simple Columnar.
 Reference: 
www.mesacc.edu