What is stratified epithelium?

A stratified epithelium is made up of two or more layers of epithelial cells stacked on top of each other. Only the lowermost layer, the basal layer, is attached to the basal membrane. The cells in this layer are capable of undergoing mitotic division and producing new epithelial cells to replenish or replace the damaged or detached surface cells. 

The multilayered nature of the stratified epithelium makes it dense and tough allowing it to adequately protect the underlying tissue. The most common example of stratified epithelial tissue is the epidermis of skin. 

The stratified epithelium can be further classified into three types based on the shape of the epithelial cells. 

The stratified squamous epithelium is made up of multiple layers of flat cells. It plays a pivotal role in protecting the underlying tissues against microorganisms, physical injury, and water loss.  

The stratified cuboidal epithelium is composed of multiple layers of cube-like cells that have equal length, width, and height. It is found in the excretory ducts of the salivary and sweat glands. 

The stratified columnar epithelium is composed of multiple layers of elongated rectangular column-like cells and is protective and mucus-secreting. It can be found in small amounts in the conjunctiva lining the eyelids and in the male urethra.