Biomedical Engineering Reference
In-Depth Information
5
Skin grafts
S. D. IMAHARA M. B. KLEIN
University of Washington, USA
and
Abstract::
The ideal replacement for missing skin is skin itself. To date,
there remains no permanent off-the-shelf replacement that provides the
physical and physiologic functions of human skin. This chapter will discuss
the biology of skin, the history of skin graft use, the immunology of skin and,
finally, the techniques of autograft, allograft and xenograft usage.
Key words:
autologous skin graft, allograft, xenograft, full thickness skin
graft, split thickness skin graft.
5.1 Definitions
Several terms are pertinent to this discussion and require definition. A
graft
is
tissue separated from its donor bed and relies on nutrient delivery from the
recipient tissues. An
autograft
(or autologous graft) refers to tissue transplanted
from one location to another in the same individual.
Isograft
refers to tissue
transplanted between genetically identical twins. An
allograft
(termed
homograft
in older texts) is tissue transplanted between unrelated individuals of the same
species. A
xenograft
(termed
heterograft
in older texts) is tissue transplanted
between individuals of different species.
Split thickness skin graft
refers to skin
grafts that contain all of the epidermis and a variable amount of the dermis;
whereas
full thickness skin grafts
are grafts that contain epidermis and all the
dermis and associated dermal appendages.
5.2
Skin anatomy and physiology
The skin performs numerous important roles. It provides a protective layer against
mechanical, chemical and microbiologic insults and it performs crucial roles in
thermoregulation and ultraviolet radiation protection. In addition the skin is a
primary sensory organ and is important in vitamin D metabolism. The skin consists
of two distinct layers: the epidermis and the dermis (
Fig. 5.1
). The outermost layer,
the epidermis, is derived embryologically from ectoderm. Similar to other
ectodermally derived structures, the epidermis is capable of regeneration. Wounds
involving only the epidermis heal by regeneration of epidermal cells not only from
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