Why are scars permanent?

Scars come in all shapes, sizes and colors and are the result of the skin's natural healing process after damage, whether it's caused by surgery, infection, injury or rapid body growth.

Scars serve an important role: They enable the body to replace lost or disfigured tissue. But what are scars made of? And why are they permanent?

To answer these questions, first it's necessary to clarify what a scar is.

The skin is made of three main layers. The outermost layer of skin, known as the epidermis, is the thinnest layer. It's composed of layers of flattened cells, called epithelial cells, which collectively act as armor, protecting the body from the outside world.

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Underneath the epidermis is the dermis, the thickest layer of skin that contains nerves, blood vessels, hair follicles and sweat and oil glands. Within the dermis, there is also a large, fibrous network of proteins called collagen and elastin that, respectively, support the structure and elasticity of the skin. Finally, the hypodermis is the deepest layer of the skin. It contains fatty tissue for insulating the body, cushioning internal organs and shielding tissues from injury.

If you damage only the epidermis — such as in most cases of sunburn — this outer layer of skin will just peel off, leaving the deeper layers of skin intact. But if an injury penetrates deep into the dermis, the body then has to repair this damaged tissue. A scab forms to seal the wound, and then iNFLaMMAtion initiates healing. Then, the skin begins to remodel the tissue within that wound, and the haphazard way it does this is what causes a scar to form.