The most prevalent of the stratified epithelia is the squamous variety. Keratinized Type Keratinized stratified squamous epithelium is identified by the multiple layers of dead cells at the surface. Keratin accumulation within maturing cells effectively waterproofs the cells, blocking diffusion of nutrients and wastes. The cells subsequently die. Thick skin has many layers of these dead cells cemented together.
Thin skin has fewer layers of living and dead cells but same structure.
This mucous variety also occurs in the rectum and lower portions of the female reproductive tract. A key attribute of this mucous stratified squamous type is observed in the surface cells. In contrast to the keratinized stratified squamous epithelium, flattened surface cells of a mucous type are nucleated and living. The name transitional comes from the ability of this epithelium to accommodate stretching in the urinary tract as fluid pressures vary. It is found as a lining of the ureters, urethra, and bladder.