INTEGUMENTARY SYSTEM I. Two Types A. Invertebrate type epidermis plus basement membrane pnotochordat

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The Integument
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INTEGUMENTARY SYSTEM

• I. Two Types A. Invertebrate type - epidermis
  plus basement membrane - protochordatesB.
  Vertebrate type complex dermis
  epidermis Trends -
• thin in anamniotes
• thick in amniotes

Epidermis
Basement Membrane
Epidermis
Dermis
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II. Dermal Derivatives

• A. Dermal armor 1. Dermal bone -
  Ostracoderms 2. Cosmoid scale of primitive
  fishes gave rise to dermocranium and dermal
  girdles

Cosmoid Scale
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Fish Scales

• 3. Placoid scale of chondrichthyes

Shark placoid scales and teeth
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• 4. Ganoid scales of gar and sturgeons
• contain the protein ganoin
• 5. Leptoid scale - loss of ganoinand gave rise
  to the cycloid
• scale ctenoid scale (with ctenii)

Cycloid scales
Ctenoid scales
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Other Dermal Derivatives

• 6. Osteoderms - crocodilia
• 7. Secondary dermal armor - armadillo shell

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B. Scale derivatives 1. Branchiostegal rays
- rods of bone supporting the ventral pharyngeal
wall in fish 2. Bony plates of sturgeons
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Summary of Dermal Derivatives

• C. Dermal armor derivatives 1.
  Dermocranium 2. Teeth 3. Dermal girdle
  4. Body scales 5. Osteoderms - crocodilians
  and some lizards 6. Specialized dermal boney
  shells (dermal bone of armadillo)
• Turtles -

Insert Fig. 6.36
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and Finally

• D. Chromatophores - derived from embryonic
  nervous system1. Types a. melanophores -
  brown to black pigments
• b. lipophores xanthophores - yellow
  erythrophores - red c. guanophores - white d.
  iridocytes - contain crystalsAll controlled by
  hormones

Light
Dark
Pigment
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Malanophores
In most vertebrates, MSH is produced by an
intermediate lobe of the pituitary gland. Its
secretion causes a dramatic darkening of the skin
of fishes, amphibians, and reptiles. The
darkening occurs as granules of melanin spread
through the branches of specialized melanocytes
called melanophores.
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III. Epidermal Derivatives

• A. Epidermal seal cuticle - nonliving layer in
  protochordates, lung fishes, and larval
  amphibiansmucoid coat - mucous - fish,
  amphibians
• keratin - in all, but more pronounced in
  terrestrial vertebratesSquamous cytoplasm
  granules form keratin that is first prevalent in
  reptiles and shed - ecdysis

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B. Epidermal scales - reptiles, birds, mammals
Keratin - soon to be shed New Kertin
layer Mitotic Layer of epidermis Dermis
Reptilian scales
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C. Claws and Nails
Unguis - keratinized nail Subunguis - living
tissue that generates ungus Pad
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E. Hooves
Unguis Subunguis Pad or cuneus (frog)
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F. Glands

• 1. Ancestral serous glands - precursor to the
  glands below
• 2. Poison glands amphibians frog licking
• 3. Wax glands - birds mammals

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• 4. Tubular glands - mammals
• 5. Sweat and
• Mammary glands
• 6. Modern serous glands - Holocrine - cells shed
  and degenerate into fluidscent glands
  (reptiles)mucous glandssebaceous gland - oil
  scent glands of mammalsuroptygial gland -
  oil gland on tail of birds

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G. Hair
Develops from epidermis and protrudes or grows
into the dermis
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Evolution of Hair

• No fossil evidence of origin of hair
• Possibly arose from sensory structures of
  reptiles called prototrichs

Reptilian scales with triads of prototrichs
Hairs of mammals arranged in triads today.
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H. Feathers

• 1. Formation
• 2. Types a. Down - fluffyb. Filoplumes -
  hairlike c. Contour

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c. Contour feathers
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I. Horns J. Antlers
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Pronghorn Bone covered with keratin Large horn
in males, small spike in females
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K. Baleen - keratinized plates for filtering
food in balleen whales