The most direct way to different types of epithelium tissue is by the number of cell layers and by the shape of the cells. As for the layers, they can be simple, if there is only one layer of cells, or stratified, if there is more than one layer of cells. Related to the shape of the cells it can be a squamous epithelium, a cuboid epithelium, a columnar epithelium, or transitional when the cell can adopt different shapes so that the epithelium can be stretched.