Within the epidermis, there are four major layers of cells called keratinocytes that provide structural support for the skin. In addition to these four layers, you have another layer specific to your soles and palms, called the stratum lucidum.
This article describes the layers of cells in the epidermis, including their structure and function.
Basal cells are constantly dividing and pushing already-formed cells towards the skin’s surface. As basal cells move into the upper layer, they will also flatten, die, and be shed to make room for newer cells.
Melanocytes, the cells that produce melanin—the pigment which provides your skin its color—are also found in this layer.
Cells in this layer are responsible for making keratin. This is the fibrous protein that gives skin, hair, and nails their hardness and water-resistant properties.
They appear as flattened cells containing dark clumps of cytoplasmic material, which are the parts of the cell minus the nucleus.
There is a lot of activity in this layer. Keratin proteins and lipids work together to create many of the cells responsible for the skin’s protective barrier.
The name itself comes from the Latin for “clear layer,” which describes the transparency of the cells themselves.
Composed mainly of keratin proteins, corneocytes provide structural strength to the stratum corneum but also allow for the absorption of water. They serve as an effective barrier to any chemicals that might harm the living cells just beneath them.
The structure of the stratum corneum may look simple, but it plays a key role in maintaining the structural integrity and hydration of the skin.
It ensures the continued production of new skin cells. It also provides vital protection against viruses, bacteria, parasites, and any other form of pathogen or toxin.
The four layers of cells, beginning at the bottom, are the stratum basale, stratum spinosum, stratum granulosum, and stratum corneum. In your palms and soles, there’s an additional layer called stratum lucidum underneath the stratum corneum.
In the bottom layer, keratinocytes divide and push up formed cells toward the upper layer. The cells that reach the surface flatten and die. This provides a barrier to keep out pathogens and protect new skin cells underneath.
