Skin is composed of three primary layers: the epidermis, the dermis and the hypodermis (subcutis).

Human skin shares anatomical, physiological, biochemical and immunological properties with other mammalian lines, especially pig skin. Pig skin shares similar epidermal and dermal thickness ratios to human skin; pig and human skin share similar hair follicle and blood vessel patterns; biochemically the dermal collagen and elastic content is similar in pig and human skin; and pig skin and human skin have similar physical responses to various growth factors.

Skin plays an important immunity role in protecting the body against pathogens and excessive water loss. Its other functions are insulation, temperature regulation, sensation, synthesis of vitamin D, and the protection of vitamin B folates. Severely damaged skin will try to heal by forming scar tissue. This is often discoloured and depigmented.

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