What are the similarities between simple and stratified epithelial tissue?

Simple and stratified epithelial tissue are types of tissues that form the outer lining of organs, protecting the organs within. 

The epithelial cells in both types are packed together tightly with no intercellular space, which is integral to preventing the movement of substances through spaces in the cells. The epithelial cells are held together by cell junctions.  

Both simple and stratified epithelial tissue can be classified as squamous, cuboidal or columnar, based on the shape of the cells. Both types of tissues contain a basement membrane to which one surface of the cells are attached. The other surface is apical or exposed to the external environment. 

Both types of epithelial tissues are avascular – they do not contain their own blood vessels. They receive the nutrition they need through diffusion from connective tissue underlying the basement membrane.