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.
Now let's zoom in on the actual cells that make up the epidermis. In general, the skin is made of epithelial cells, or cells that are tightly packed together in layers. Cells known as keratinocytes are the primary members of the epidermis. These are the cells that are made by the stratum basale and move outwards towards the stratum corneum.