Stratified squamous epithelium:
• This epithelium has several layers of epithelial cells, but the surface layer of this epithelium is composed of flat cells. It is the thickest of all the epithelia and its function is protection.
• The cells of the surface layer may or may not contain keratin, a tough protective protein which prevents water loss, is resistant to friction and repels bacteria.
• Keratinized, stratified squamous epithelium forms the epidermis of the skin.
• Non-keratinized stratified squamous epithelium lines wet surfaces subjected to abrasion, such as the lining of the mouth, oesophagus, tongue, part of the epiglottis and vagina.