Epidermis (skin)
From Free net encyclopedia
Epidermis is the outermost layer of the skin. It forms the waterproof, protective wrap over the body's surface and is made up of stratified squamous epithelium with an underlying basal lamina. It contains no blood vessels, and is nourished by diffusion from the dermis. The main type of cells which make up the epidermis are keratinocytes, with melanocytes and Langerhans cells also present. Epidermis is divided into several layers where cells are formed through mitosis at the innermost layers. They move up the strata changing shape and composition as they differentiate and become filled with keratin. They eventually reach the top layer called stratum corneum and become sloughed off, or desquamated. This process is called keratinization and takes place within weeks. The outermost layer of Epidermis consists of 25 to 30 layers of dead cells.
Epidermis is divided into the following 5 sublayers or strata:
- Stratum corneum
- Stratum lucidum
- Stratum granulosum
- Stratum spinosum
- Stratum germinativum also called stratum basale
A mnemonic that is good for remembering the layers of the skin is:
"Corn Lovers Grow Several Bales"
or "Before sex, get latex condoms" (care of Lucia Tranel at St. Louis College of Pharmacy)
eo:Epidermo fr:Épiderme (anatomie) he:אפידרמיס lt:Epidermis nl:Epidermis pl:Naskórek fi:Orvaskesi sv:Överhud zh:表皮 (皮膚)