1 All Physician Training licenses expire on August 31, 2015, are good for three years, and can only renew once (for a total of six years). 2  All Physician Assistant licenses expire on January 31 of even-numbered years.  All Anesthesiologist Assistant licenses expire on January 31 of even-numbered years.
The epidermis is the uppermost or epithelial layer of the skin. It acts as a physical barrier, preventing loss of water from the body, and preventing entry of substances and organisms into the body. Its thickness varies according to body site. The epidermis consists of stratified squamous epithelium.
Structure and Function: 95% of the cells in the epidermis are keratinocytes. These cells are found in the basal layer of the stratified epithelium that comprises the epidermis, and are sometimes referred to as basal cells, or basal keratinocytes.quamous keratinocytes are also found in the mucosa of the mouth and esophagus, as well as the corneal, conjunctival, and genital epithelia. These cells are responsible for forming tight junctions with the nerves of the skin. They also keep Langerhans cells of the epidermis, and lymphocytes of the dermis, in place.