Skin structure and wound healing

Skin consists of three main layers: the outer epidermis, the underlying dermis, and the deep follicles hypodermis.

The epidermis

The epidermis has five layers. Cells at the base, the basal cell layer, divide and continually push the older cells towards the surface where they are eventually shed. A gradual process transforms the round, nucleated cells of the basal layer into the flattened, keratin-rich ones found on the outer surface of the epidermis. This top layer of dead skin cells, called the “stratum corneum”, is where Strataderm dries and bonds to form a silicone gel sheet. This is a protective waterproof barrier that retains moisture, is gas permeable and assists the skin to continue to expel and “breathe”. Repair of damaged epidermis occurs by regeneration. The cells of the basal layer multiply and migrate from undamaged areas to replace damaged cells. The eventual repair has a normal structure and appearance and leaves no visible scar.

 

The dermis

The dermis consists of collagen and elastin fibers, supplied by a rich network of small blood vessels. The dermis supports the epidermis. Dermal elastin supplies the elasticity and collagen provides the tensile strength of the skin. Specialized skin structures such as hair follicles, sebaceous and sweat glands also lie within the dermis.

Repair of damaged dermis is dependent on the level of trauma. Healed superficial dermal damage may be clinically indistinguishable from normal skin. Full-thickness damage to the dermis is repaired by a process called granulation and can result in the formation of a permanent, visible scar.1

 

The hypodermis

The dermis is attached to the underlying loose tissue called the hypodermis. This layer consists of various amounts of adipose, or fat tissues as well as specialized skin structures that are also found in the dermis above.

 

1. Bayat A et al. BMJ 2003; 326:88–92