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.
The superficial layer of skin. It is composed of squamous epithelium cells. These are flat scale-like cells that are arranged in layers, called stratified squamous epithelium. The many layers of the epidermis create a barrier to infection.The epidermis does not have a blood supply, so it is dependent on the deeper layers of skin for nourishment. However, the deepest epidermis layer is called the basal layer. These cells are alive and constantly dividing.he many layers of the epidermis create a barrier to infection. The epidermis does not have a blood supply, so it is dependent on the deeper layers of skin for nourishment. However, the deepest epidermis layer is called the basal layer.