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The Integument

The Integument. INTEGUMENTARY SYSTEM. Epidermis. I. Two Types A. Invertebrate type - epidermis plus basement membrane - protochordates B. Vertebrate type complex dermis + epidermis Trends - thin in anamniotes thick in amniotes. Basement Membrane. Epidermis. Dermis. Leptoid Scale.

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The Integument

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  1. The Integument

  2. INTEGUMENTARY SYSTEM Epidermis I. Two Types A. Invertebrate type - epidermis plus basement membrane - protochordatesB. Vertebrate type complex dermis + epidermis Trends - thin in anamniotes thick in amniotes Basement Membrane Epidermis Dermis

  3. Leptoid Scale Ganoid Scale Placoid Scale Cycloid Scale Ctenoid Scale Teeth 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

  4. Fish Scales 3. Placoid scale of chondrichthyes Shark placoid scales and teeth

  5. 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

  6. Other Dermal Derivatives 6. Osteoderms - crocodilia 7. Secondary dermal armor - armadillo shell

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

  8. 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

  9. and Finally D. Chromatophores - derived from embryonic nervous system1. Types a. melanophores - brown to black pigments b. lipophores & xanthophores - yellowerythrophores - red c. guanophores - white d. iridocytes - contain crystalsAll controlled by hormones Light Dark Pigment

  10. 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.

  11. 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

  12. B. Epidermal scales - reptiles, birds, mammals Keratin - soon to be shed New Kertin layer Mitotic Layer of epidermis Dermis Reptilian scales

  13. C. Claws and Nails Unguis - keratinized nail Subunguis - living tissue that generates ungus Pad

  14. E. Hooves Unguis Subunguis Pad or cuneus (frog)

  15. F. Glands 1. Ancestral serous glands - precursor to the glands below 2. Poison glands – amphibians & frog licking 3. Wax glands - birds mammals

  16. 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

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

  18. Sensory fiber Sensory nerve 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.

  19. H. Feathers 1. Formation 2. Types a. Down - fluffyb. Filoplumes - hairlike c. Contour

  20. Barb Barbicelle c. Contour feathers

  21. Velvet (not shed) with boney core Bone covered by velvet that is shed Antler Giraffe horn Keratin throughout Keratin with boney core Bovine horn Rhino horn I. HornsJ. Antlers

  22. Pronghorn Bone covered with keratin Large horn in males, small spike in females

  23. K. Baleen - keratinized plates for filtering food in balleen whales

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