What is the Dermis?
The dermis is the second layer of skin in our bodies. It is comprised mostly of water, elastic fibers, and other important structures that serve to support the skin.
What is the Difference between the Dermis and the Epidermis?
The epidermis is the outmost layer of visible skin. The cells in the epidermis have undergone keratinization and have hardened. Keratinization is also the same process that causes hair to mature and prepare for shedding.
Just below the epidermis is an even thicker layer called the dermis. Cells at this level are alive and divide rapidly. They are eventually pushed to the surface so that they may undergo keratinization as well.
Structures of the Dermis
The dermis contains the following characteristics:
- Connective tissue – this is usually in the form of densely-packed protein fibers called collagen. Collagen is what gives skin its strength and durability. As a person ages, their collagen becomes hardened, and the skin is less elastic. This is what creates wrinkling.
- Nerve endings – these sensory fibers send textural clues to the brain when stimulated by touch. It is what allows the body to feel the sensations of pleasure and pain.
- Sebaceous glands – also known as “sweat glands”, these formations resemble tightly coiled tubes. They produce sebum, which helps to moisturize the skin. This also serves as a barrier to protect the skin from bacterial and fungal infections.
- The papillary dermis – this is the highest level of the dermis, and it merges with the epidermis through the use of collagen. The papillae in this area are what connects the epidermis to its blood supply. The dermo-epidermal junction – this small structural support system is what allows the dermal and epidermal layers to exchange cells and molecules such as keratinocytes.
- The reticular dermis – this is the lower level. Collagen at this level simultaneously grows in all different directions. Collagen does not grow in a single uniform direction until it reaches closer to the epidermis itself.
The Dermis and Fibroblasts
Dermal fibroblasts are the primary types of cells found in this layer of skin. They are found in much greater abundance at the higher levels of the dermis, and hardly at all in the lower levels. Although these cells do not change into other cell types, they are responsible for producing collagen (with the help of keratinocytes) and other crucial elastin fibers.
When it comes healing the skin from injury, fibroblasts play a critical role. They are what directs the collagen to regrow over the wound, and they are also what signals a new migratory path for the blood vessels to take immediately after a wound occurs.
Fibroblasts and Stem Cell Therapy
Stem cells can be considered “blank cells”, or cells that can transform into whatever type of cell is necessary to heal an injury. Fibroblasts produce certain kinds of proteins that can help stabilize and improve the survivability of stem cells. For this reason, dermal fibroblast cells are often removed from the body’s tissue and cultivated with stem cells. Dermal fibroblasts can even become stem cells themselves, though their uses are limited.