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→Immunology
See also [[Skin - immunologic|Skin Immunology]]
See also [[Skin - immunologic|Skin Immunology]]
==Species Differences==
===Avian Skin===
The general make-up of the avian skin is similar to that of mammals, having an ''epidermis'' a ''dermis'' and a ''subcutaneous layer''. In comparison, however, it is much thinner, effectively glandless and contains [Feather - Anatomy & Physiology|feathers]]. Generally, the skin is thin enough to be transparent, aiding examination of superficial internal organs including the liver.
The '''epidermis''' consists of 3 layers:
* The basal (germinative) layer
* Intermediate layer
* Outer (cornified) layer
Striated muscles in the epidermis move the skin.
The '''dermis''' is divided into:
* A superficial layer which varies in thickness depending on position on the body and age of the bird. This layer contains loosely arranged layers of collagen in interwoven bundles.
* A deep layer containing fat, [Feather - Anatomy & Physiology|feather follicles]], smooth muscles that control the movement of the feathers, blood vessels and nerves that supply the dermis and epidermis.
The '''subcutaneous layer''' is formed mainly by loose connective tissue. It also contains fat, both as a layer, and in discrete fat bodies. These are readily observed as yellow deposits beneath the skin.
Areas of fat deposition vary from species to species (high in aquatic birds) and the time of year (pre-migration deposition).
Common areas of fat deposition are lateral to the pectoral muscles, in the cloacal region and on the dorsum.
==Links==
==Links==
http://en.wikipedia.org/wiki/Feathers
http://en.wikipedia.org/wiki/Feathers