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Structure and function of the skin
/content/chapter/10.22233/9781905319886.chap1
Structure and function of the skin
- Authors: David H. Lloyd and Anita Patel
- From: BSAVA Manual of Canine and Feline Dermatology
- Item: Chapter 1, pp 1 - 11
- DOI: 10.22233/9781905319886.1
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Copyright:
- Publication Date: September 2012
Abstract
PLEASE NOTE A NEW 4TH EDITION HAS BEEN PUBLISHED AND IS AVAILABLE IN THE LIBRARY AND IN PRINT
The skin is the largest of the organs. It performs a wide variety of functions vital to maintenance of the homeostatic status of the body and plays an active role in immune responses via the innate and acquired immune system. In addition, different regions of the skin such as the ears, eyelids, lips, prepuce, footpads and claws have specialized functions and differ structurally from the skin that covers the general body surface. A consideration of all these topics is beyond the scope of this chapter. Attention will be concentrated on the anatomy and physiology of the unspecialized skin and its role in body defence, with the aim of providing a basis for understanding the pathogenesis of cutaneous disease. The chapter focuses on the epidermis; hair and its associated structures; the dermoepidermal junction; the dermis, and the skin as an immune organ.
/content/chapter/10.22233/9781905319886.chap1
Figures
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1.2
Epidermis showing the organization of the cells and their maturation into fully cornified cells. © Anita Patel. © 2012 British Small Animal Veterinary Association
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Epidermis showing the organization of the cells and their maturation into fully cornified cells. © Anita Patel.
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1.4
Scanning electron mircrograph of frozen hydrated canine stratum corneum, showing the compact layered arrangement of the squames. (Courtesy of IS Mason and DH Lloyd) © 2012 British Small Animal Veterinary Association
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Scanning electron mircrograph of frozen hydrated canine stratum corneum, showing the compact layered arrangement of the squames. (Courtesy of IS Mason and DH Lloyd)
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1.5
Frozen section of bovine skin after treatment with an alkaline buffer, swelling the stratum corneum. Red-staining lipid (Sudan IV stain) can be seen in the distal intercellular layers of the corneum. The stratum corneum is somewhat thinner in dogs and cats. LE = living epidermis; SC = stratum corneum. © 2012 British Small Animal Veterinary Association
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1.5
Frozen section of bovine skin after treatment with an alkaline buffer, swelling the stratum corneum. Red-staining lipid (Sudan IV stain) can be seen in the distal intercellular layers of the corneum. The stratum corneum is somewhat thinner in dogs and cats. LE = living epidermis; SC = stratum corneum.
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1.6
The hair growth cycle. Anagen, the active growth phase, is divided into six stages: proanagen, stages I–IV; mesanagen, stage V; and metanagen, stage VI. During these stages the hair follicle undergoes differentiation, rapid growth and hair elongation. Telogen represents the resting phase of the hair follicle, and catagen is the transitional period between the growth and resting phases. © Anita Patel. © 2012 British Small Animal Veterinary Association
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The hair growth cycle. Anagen, the active growth phase, is divided into six stages: proanagen, stages I–IV; mesanagen, stage V; and metanagen, stage VI. During these stages the hair follicle undergoes differentiation, rapid growth and hair elongation. Telogen represents the resting phase of the hair follicle, and catagen is the transitional period between the growth and resting phases. © Anita Patel.
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The hair follicle and its associated structures. © Anita Patel. © 2012 British Small Animal Veterinary Association
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The hair follicle and its associated structures. © Anita Patel.
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1.10
Scanning electron micrograph of a normal canine hair. The surface is tiled with cells of the cuticle, which point away from the base of the hair. © 2012 British Small Animal Veterinary Association
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1.10
Scanning electron micrograph of a normal canine hair. The surface is tiled with cells of the cuticle, which point away from the base of the hair.
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1.12
Components of mammalian skin, including epidermal structures (compound hair follicle and adnexal structures, free sebaceous gland, atrichial sweat gland), blood supply, nerves and associated mechanoreceptors. © Anita Patel. © 2012 British Small Animal Veterinary Association
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Components of mammalian skin, including epidermal structures (compound hair follicle and adnexal structures, free sebaceous gland, atrichial sweat gland), blood supply, nerves and associated mechanoreceptors. © Anita Patel.
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Structural components of the dermoepidermal junction. © Anita Patel. © 2012 British Small Animal Veterinary Association
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Structural components of the dermoepidermal junction. © Anita Patel.
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1.14
Section through canine skin, illustrating the dermal connective tissue structure. (a) The deep dermis is characterized by thicker and denser collagen (silver stain). (b) High-power view showing elastin fibres surrounding a hair follicle. (Gomori’s aldehyde fuchsin with light green stain: collagen = green; elastin fibres = mauve.) © 2012 British Small Animal Veterinary Association
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1.14
Section through canine skin, illustrating the dermal connective tissue structure. (a) The deep dermis is characterized by thicker and denser collagen (silver stain). (b) High-power view showing elastin fibres surrounding a hair follicle. (Gomori’s aldehyde fuchsin with light green stain: collagen = green; elastin fibres = mauve.)
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1.15
A section of bovine skin stained with haematoxylin following arterial perfusion with Indian ink. Note that the thin, superficial epidermal tissue is avascular. © 2012 British Small Animal Veterinary Association
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1.15
A section of bovine skin stained with haematoxylin following arterial perfusion with Indian ink. Note that the thin, superficial epidermal tissue is avascular.