As the outermost cells age and wear down, they are replaced by new layers of strong, long-wearing cells. The stratum corneum is also known as the "horny layer," because its cells are toughened like an animal's horn. The stratum corneum is the outermost layer of the epidermis, and is made up of 10 to 30 thin layers of continually shedding, dead keratinocytes. This process results in the cells fusing together into layers of tough, durable material, which continue to migrate up to the surface of the skin. As these cells move further towards the surface of the skin, they get bigger and flatter and adhere together, and then eventually become dehydrated and die. The keratinocytes from the squamous layer are then pushed up through two thin epidermal layers called the stratum granulosum and the stratum lucidum. The Stratum Granulosum & the Stratum Lucidum
TRANSLUCENT CELLS CONTAINING KERATIN CALLED SKIN
These cells attach themselves to antigens that invade damaged skin and alert the immune system to their presence. The squamous cell layer also contains cells called Langerhans cells. The squamous cell layer is the thickest layer of the epidermis, and is involved in the transfer of certain substances in and out of the body. Keratinocytes produce keratin, a tough, protective protein that makes up the majority of the structure of the skin, hair, and nails. Within this layer are the basal cells that have been pushed upward, however these maturing cells are now called squamous cells, or keratinocytes. The squamous cell layer is located above the basal layer, and is also known as the stratum spinosum or "spiny layer" due to the fact that the cells are held together with spiny projections. Merkel cells, which are tactile cells of neuroectodermal origin, are also located in the basal layer of the epidermis. Melanoma develops when melanocytes undergo malignant transformation. Patches of melanin in the skin cause birthmarks, freckles and age spots. Sun exposure causes melanocytes to increase production of melanin in order to protect the skin from damaging ultraviolet rays, producing a suntan. Melanocytes produce the skin coloring or pigment known as melanin, which gives skin its tan or brown color and helps protect the deeper layers of the skin from the harmful effects of the sun. The basal cell layer contains cells called melanocytes. The basal cell layer is also known as the stratum germinativum due to the fact that it is constantly germinating (producing) new cells. The basal cells continually divide, and new cells constantly push older ones up toward the surface of the skin, where they are eventually shed. The basal layer is the innermost layer of the epidermis, and contains small round cells called basal cells. The epidermis layer itself is made up of five sublayers that work together to continually rebuild the surface of the skin: The Basal Cell Layer
The epidermis contains the melanocytes (the cells in which melanoma develops), the Langerhans' cells ( involved in the immune system in the skin), Merkel cells and sensory nerves. 05 mm thick on the eyelids, and is 1.5 mm thick on the palms and the soles of the feet. The thickness of the epidermis varies in different types of skin it is only. The epidermis is the outermost layer of the skin, and protects the body from the environment. In a growing fetus, fingerprints form where the cells of the stratum basale meet the papillae of the underlying dermal layer (papillary layer), resulting in the formation of the ridges on your fingers that you recognize as fingerprints.Acknowledgements Layers of the Skin The Epidermis Melaningives hair and skin its color, and also helps protect the living cells of the epidermis from ultraviolet (UV) radiation damage. The second is a melanocyte, a cell that produces the pigment melanin. These cells are especially abundant on the surfaces of the hands and feet. The first is a Merkel cell, also known as a tactile cell, which functions as a receptor and is responsible for stimulating sensory nerves that the brain perceives as touch. Two other cell types are found dispersed among the basal cells in the stratum basale. As new cells are formed, the existing cells are pushed superficially away from the stratum basale. All of the keratinocytes are produced from this single layer of cells, which are constantly going through mitosis to produce new cells. A basal cellis a cuboidal-shaped stem cell that is a precursor of the keratinocytes of the epidermis. The stratum basale is a single layer of cells primarily made of basal cells. (Image credit: "Layers of Epidermis" by OpenStax is licensed under CC BY 3.0) The epidermis of thick skin has five layers: stratum basale, stratum spinosum, stratum granulosum, stratum lucidum, and stratum corneum.
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