1. Comparative Anatomy Integument
Note Set 6
Chapter 6

2. Integument Epidermis derived from ectoderm
Figure 8.1
Epidermis derived from ectoderm
Gives rise to glands
Dermis derived from mesoderm

3. Figure 8.3: Amphibian skin showing mucous and poison glands.
Figure 8.2: Poisonous Dart Frog.

4. Modifications Presence or absence of bone in dermis
Glands in aquatic forms
Specializations in epidermis of land dwellers
Figure 8.4: African hairy frog with specialized hairs acting as auxiliary respirator organs.

5. Function of Skin Protection Respiration Temperature Control
Nourishment of Young
Locomotion and reproductive structures
Figure 8.5: African clawed frog (Xenopus laevis) was used for pregnancy test and spread chytrid fungus around the world.

6. Fish Skin No stratum corneum Many unicellular glands Photophores
Like goblet cells, secretes mucus
Photophores

7. Dermal Scales Dermal bone plates became skull Ancient armor
Rhomboid scales
Modern fish
Cycloid and ctenoid scales
Placoid and ganoid scales
Figure 8.6
Figure 8.7: Cycloid, ctenoid, placoid, and ganoid scales of modern fish.

8. Figure 8.8: Derivatives of primitive dermal bone.

9. Dermal Scales Ctenoid scales Fish have no epidermal scales
Figure 8.9
Ctenoid scales
Growth rings or annuli
Fish have no epidermal scales
Scales are dermal

10. Amphibian Skin Loses dermal scales
Exception: caecilian
Epidermal multicellular glands abundant
Stratum corneum

11. Integumentary Gland Type
Figure 8.10
Simple tubular
Plethodontid mental glands associated with courtship glands
Simple coiled tubular
Sweat glands
Simple branched tubular
Female plethodontid- spermatotheca
Simple alveolar (acinar)
Mucous glands

12. Compound branched alveolar
Figure 8.11
Compound tubular
Mammary glands of monotremes
Compound branched alveolar
Mammary glands of placentals
Courtship glands

13. (a) Simple tubular, (b) Coiled tubular,
Figure 8.12: Morphological varieties of multicellular glands.
(a) Simple tubular, (b) Coiled tubular,
(c) Simple branched tubular, (d) Compound tubular,
(e) Alveolus of simple saccular gland, (f) Simple branched saccular,
(g) Compound alveolar

14. Plethodontid (lungless salamander) Mating
Internal fertilization
Male: mental glands on chin, cloacal glands to form spermatophore, and caudal courtship glands
Female: spermatheca for sperm storage
Glands secrete pheromones
(a)
(b)
Figure 8.13: (a) Plethodontid sal. (b) spermatophore.

15. Mating
(a)
(b)
(c)
Figure 8.14: (a) mental glands, (b) cloaca, (c) nasolabial groove.

16. Modes of Secretion
Merocrine
Holocrine
Apocrine
Figure 8.15

17. Merocrine Holocrine Cell body not injured
Release particles by exocytosis
Most sweat glands in mammals
Holocrine
Cell body discharged with contents
Whole cell dies
Sebaceous glands
(a)
(b)
Figure 8.16: (a) merocrine and
(b) holocrine glands.

18. Apocrine Cellular products gather on surface then pinched off
Apical portion pinched off
Axillary sweat glands
Figure 8.17: Apocrine gland.

19. Reptile Skin Few glands (dry skin)
Thick stratum corneum with modifications
Epidermal scales
Figure 8.18: Desert horned lizard.

20. Some reptiles have remnants of dermal armor (osteoderms)
Osteoderms beneath some epidermal scales
Gastralia- large osteoderms
Alligator and skinks
True dermal bones
Turtles
Figure 8.19: Osteoderms (dermal plates) of alligator.

21. Turtles Shell of dermal bone Carapace (shell) – dorsal
Plastron- ventral
Mesoplastron additional bone on primitive, extinct turtles
Nuchal- diagnostic bone
Figure 8.20

22. Reptile Skin Turtles have epidermal scutes- large epidermal scales
Snakes have scutes on belly
Spikes and spines are epidermal
(a)
(b)
Figure 8.21: snake belly scutes (a) and white bony plate of turtle with scutes removed.

23. Reptile Integumentary Glands
Femoral pores
Occur ventrally, waxy excretion
Many lizards, turtles and snakes have scent or cloacal glands
Snakes use forked tongue to pick up scent (Jacobson’s organ)
Figure 8.22: Prairie Rattlesnake.
Figure 8.23: Jacobson’s organ.

24. Musk Glands Scent glands Along carapace in turtles
Under lower jaw in crocodiles
Musk deer
Take secretions to make perfume

25. Skin of Birds Few epidermal scales Dermal scales are absent
Legs and beak
Dermal scales are absent
Claws- diversified
Few glands
Uropygial gland- preening gland
Dermal scales absent
Figure 8.24: Feather type.

26. Feathers Modification of reptilian scales 3 types
Contour- flight feather
provides wing shape
Down- beneath contour feather
Filoplume- long shaft
lost its vane

27. Skin of Mammals Modifications of stratum corneum Hair Vibrissae
Hair, claws, nails, hooves
Hair
Like filoplume feather and
lack detail
Vibrissae
Specialized hairs
Tactile in function
Figure 8.25: Vibrissae of harbor seal.

28. Cornified Structures Baleen Plate Tori pads
Toothless whale’s horny sheets of oral ectoderm
Not bone
Used for filter feeding
Tori pads
Epidermal pads
Figure 8.26: Products of stratum corneum—tori.

29. Horns Horns In Bovine family Outgrowth of dermal core Unbranched
Covered by epidermal horny, keratinized sheath
Permanent
Figure 8.27: Bovine horn.

30. Antlers Antlers and horns of giraffe Deer Dermal bones
Dermal bone of antler attaches to skull bone
Shed annually
Outside layer is highly vascularized
Figure 8.28: Antler.

31. Figure 8.29: (a) horns and (b) antlers.

32. Dermal Pigments Chromatophores contain pigment granules
Melanophores (brown)
Melanin granules
Lipophores (yellow and red)
Iridophores or guanophores (iridescent)
Contain reflective guanine crystals

33. Literature Cited
Figure
Figure
Figure 8.3 & Kardong, K. Vertebrates: Comparative Anatomy, Function, Evolution. McGraw Hill, 2002.
Figure
Figure
Figure
Figure
Figure 8.8, 8.12 & Kent, George C. and Robert K. Carr. Comparative Anatomy of the Vertebrates. 9th ed. McGraw-Hill, 2001.
Figure
Figure 8.10 &
Figure 8.13 (a)-
Figure 8.13 (b)-
Figure
Figure

34. Literature Cited
Figure 8.16 &
Figure
Figure
Figure
Figure 8.21 (a)-
Figure 8.21 (b)-
Figure
Figure
Figure
Figure
Figure
Figure