Skin graft or skin flap. Skin grafts or skin flaps are done after the scar tissue is removed. Skin grafts involve replacing or attaching skin to a part of the body that is missing skin. Skin grafts are performed by taking a piece of healthy skin from another area of the body (called the donor site) and attaching it to the needed area. Skin flaps are similar to skin grafts, where a part of the skin is taken from another area, but with the skin flaps, the skin that is retrieved has its own blood supply. The section of skin used includes the underlying blood vessels, fat, and muscles. Flaps may be used when the area that is missing the skin does not have a good supply of blood because of the location or because of damage to the vessels.
Because steroids are lipophilic, they diffuse easily through the cell membranes, and therefore have a very large distribution volume. In their target tissues, steroids are concentrated by an uptake mechanism which relies on their binding to intracellular proteins (or " receptors ", see below). High concentration of steroids are also found in adipose tissue, although this is not a target for hormone action. In the human male, adipose tissue contains aromatase activity, and seems to be the main source of androgen-derived estrogens found in the circulation. But most of the peripheral metabolism occurs in the liver and to some extent in the kidneys, which are the major sites of hormone inactivation and elimination, or catabolism (see below).