There are three types of epidermis cells: basic cells, cells of the stoma complexes and trichomes

Added: 12/02/2005

Epidermis is known to be the outermost skin layer. It is made up of different epidermis cells which have not only different names, but also variable functions to be carried out. For example, squamous cells are historically identified by their look (they are thin and fattened). Such cells are the ones comprising the epithelium along with basal cells and melanocytes producing melanin.

It's a common knowledge skin consists of three main layers: epidermis, dermis and hypodermis. Epidermis is a top skin layer, the main function of which is protecting the whole human body from different external (usually harmful) factors, for example, ultraviolet, bacteria, viruses, chemicals, etc. Epidermis forms a special waterproof wrap over the body.

It's worth admitting epidermis is made up of stratified squamous epithelium containing no blood vessels. The mentioned epithelium consists of one or even more cells layers. The most outward of them is considered to be composed of scalelike, flat or platelike cells (squamous cells). Epidermis is regenerated by the keratinocyte cell lineage.

Thus, it is evident that the major part of epidermis consists of epidermis cells of one type - keratinocytes. These cells are also sometimes called basal cells for the reason they are formed in the basal layer of the epidermis. The distinguishing feature of basal cells is that they move up slowly. Periodically the mentioned epidermis cells change into a dead cellular layer where they are lying against each other looser and looser. That's why epidermis cells are renewed almost once a month. This peeling isn't usually visible for the person. The exception in this case is such disease as psoriasis.

It is very important that all epidermis cells be connected between each other. Depending on this connection the skin will be more or less protected from the dehydration.

Melanocytes are also the epidermis cells of great importance. These are special pigment cells which reside between basal cells and produce pigment grains which are in future transferred into keratinocytes via sprouts. So, depending on the quantity of basal cells and melanocytes the skin color of the person is lighter or darker. Melanocytes are the epidermis cells located in the skin's bottom layer. They take part in the process known as melanogenesis and produce melanin (the pigment in hair, skin, eyes, etc.). So, there's more melanin the skin of the people living in hot areas of the world (for example, Africa).

Thus, all the epidermis cells are known to originate from a basal cells layer on the special basement membrane. The mentioned basal layer produces special so-called "daughter cells" which step by step move upwards and begin producing skin proteins (keratins) and fats (lipids or keratinocytes). As these cells move upward they become joined by a spiny process for making another identifiable layer (so called "spiny layer"). The mentioned cells make the sphingolipids or special fats which reach stratum corneum; then an important role in the moisture retention inside the skin will be played by lipids. Later the indicated cells develop some granules that form a section of the granular layer.

Finally, the number of cells layers in the stratum corneum usually depends on the site and other important factors on the body. The stratum corneum is acting as covering of the skin and is able to resist scratches and scrapes outside.

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