Human tooth development stellate reticulum and stratum intermedium. These cells give rise to ameloblasts, which produce enamel and become a part of the reduced enamel epithelium (REE) after maturation of the enamel. The location where the outer enamel epithelium and inner enamel epithelium join is called the cervical loop. The growth of cervical loop cells into the deeper tissues forms Hertwig Epithelial Root Sheath, which determines the root shape of the tooth. During tooth development there are strong similarities between keratinization and amelogenesis. Keratin is also present in epithelial cells of tooth germ and a thin film of keratin is present on a
Human skin 20 blood vessels, 60,000 melanocytes, and more than 1,000 nerve endings. The average human skin cell is about 30 micrometers in diameter, but there are variants. A skin cell usually ranges from 25-40 micrometers (squared), depending on a variety of factors. Skin is composed of three primary layers: the epidermis, the dermis and the hypodermis. Epidermis, "epi" coming from the Greek meaning "over" or "upon", is the outermost layer of the skin. It forms the waterproof, protective wrap over the body's surface which also serves as a barrier to infection and is made up of stratified squamous epithelium with an