1. Integument Skin = composite organ
Epidermis = superficial; epithelial tissue; ECTODERMAL
Dermis = deep; connective tissue; mostly MESODERMAL
Neural Crest Cells = migrate into both epidermis and dermis; ECTODERMAL

2. Vertebrate Integument Devel.
Epidermis = generalized ectoderm + neural crest (pigment cells)
Dermis = dermatomal mesoderm + scattered neural crest cells

3. Vertebrate Embryo (section)
dermatome
vertebra
myotome
developing
skin
gut
epidermal
ectoderm
coelom
dermis
epidermis
neural crest

4. Cephalochordate Integument
Epidermis = 1 cell layer (simple epithelium)
Dermis = compact alternating layers of collagen with fibroblasts
NO neural crest
Mucus
EPIDERMIS
Basal lamina
DERMIS

5. Vertebrate/Craniate Skin
Stratified epidermis (= an epithelium)
Stratum basale (Basal Layer) = deep layer, contacts the basal lamina, mitotically active
Keratin = proteins in superficial epidermis (keratinocytes); “harden” = cornified
Stratum corneum = heavily keratinized surface layer of epidermis (only in tetrapods)
Dermis usually more complex (= conn. tissue)
Stratum laxum = more superficial & irregular (only in gnathostomes)
Stratum compactum = deep & more ordered

6. Vert./Craniate Epidermis Devel.
Epidermis begins as a simple epithelium
Then forms two-layers.
Periderm – superficial
Basal layer (stratum basale) – deep; contacts basement memb.; forms adult epidermis.

7. Dermis Devel.
First dermatome cells make layered collagen and form fibroblasts under the epidermal basement membrane = stratum compactum (contiguous with the reticular lamina)
The in gnathostomes, the stratum compactum separates from the reticular lamina of the basement membrane (delaminates).
The stratum laxum forms between the stratum compactum & the reticular lamina of the epidermis after delamination.

8. Human Integument
Stratified keratinous epidermis, strata laxum and compactum in dermis
Hair = keratinous epidermal outgrowth (with dermal pulp cavity)
Sweat glands = coiled, produce watery sweat for cooling or traction.
Sebaceous glands = associated with hair follicles, produce sebum.
Mammary glands = produce milk (similar to sweat & sebaceous glands)

9. Human Integument Stratum corneum Epidermis Hair Sebaceous gland Dermis
Sweat

10. Human Hair & Gland Devel.

11. Human Mammary Ridge and Mammary Glands
Mammary glands form regionally along mammary ridge in all therian mammals (location and number vary).

12. Human Mammary Development
Mammary Glands, single pair with nipples, fat and glandular tissue.
Supernumary (ectopic) nipples form along developmental “milk” line.

13. Human Integument Hair on all surfaces EXCEPT:
palms of hands, soles of feet, lips, nipples, penis, and clitoris
Sebaceous glands on all surfaces EXCEPT:
palms of hands and soles of feet
Sebaceous glands associated with hair follicle (except on lips, nipples, penis, and clitoris).

14. Human Skin Problems/Disease
Pimples form when a hair follicle is blocked and sebum builds up.
Skin Cancer
most common – basal cell carcinoma
most dangerous - melanoma

15. Integumentary Bones/Scales
Dermal bones = bone formed in the deep dermis around collagen by osteoblasts. e.g., some skull bones
Dermal scale = bone formed in more superficial dermis around collagen by osteoblasts. (may have epidermal contributions) e.g., some “fish” scales
Epidermal scale = proteinaceous, formed by dead keratinocytes in the epidermis. e.g., reptile scales

16. Dermal Bone Growth

17. Dermal (Bony) Scales Epidermis can contribute enamel.
Enamel = acellular CaPO4, hardest vertebrate produced substance.
Dermis can contribute 3 kinds of bone.
Dentin(e) = acellular, hard bone; under the epidermis
Dermal Vascular Bone = cellular & vascularized/“spongy”; in stratum laxum
Dermal Lamellar Bone = cellular or acellular, formed in flat layers; in stratum laxum or stratum compactum

18. Dermal Scales Enamel Dentine Vascular Bone Lamellar Bone Epidermal
Acellular
Cellular
Acellular or Cellular

19. Integumentary Glands Epidermal; secrete to skin surface
Unicellular Glands - Common in non-tetrapod epidermis; rare in tetrapods; usually produce mucus.
Multicellular Glands - Rare in non-tetrapod epidermis; common in tetrapods
(Exception: Multicellular slime glands in hagfishes)
Mucus “Cuticle” – Mucus layer covering some amphibians and all non-tetrapods; protects from abrasion and pathogens

20. Hagfish & Lampreys Keratinous (epidermal) “teeth”
No dermal or epidermal scales.

21. Petromyzontid Integument
Ammocoete larva
Epidermis
Basal layer
Basal lamina
Dermis
(stratum
compactum)

22. Placoid Scales Synapomorphy of chondrichthyans
Enamel (superficially), Dentin (deep)
Scale “erupts” from epidermis.
Central dermal pulp cavity.
Enamel
Dentin
Pulp
cavity

23. Ganoid Scales
Found in reedfishes, gars, and fossil sturgeon and bowfin
Enamel (superficially), Lamellar bone (deep), lack a pulp cavity
Scale “erupts” from epidermis.

24. Teleost Scales Lamellar bone ONLY Scale covered by epidermis.
Cycloid or Ctenoid (with projections)

25. Craniata Chondrichthys Actinopterygii coelacanths amphibians Mammalia
hagfishes
lampreys
lungfishes
Reptilia
stratified epidermis

26. Subphylum Vertebrata Chondrichthys Actinopterygii coelacanths
amphibians
hagfishes
lungfishes
lampreys
Mammalia
Reptilia
ganoid
scales
dermal
scales
lost
placoid
scales
dermal bone; dermal stratum laxum

27. Class Actinopterygii sturgeons & paddlefishes Amia (the bowfin)
reedfishes
TELEOSTS
gars
cycloid or
ctenoid
scales
(enamel lost)
ganoid scales

28. Tetrapod Integument
Stratum corneum = superficial layer of dead keratinocytes (outer epidermis)
prevents water loss; protects
- thin, underlies mucous layer in lissamphibians.
- thick, “replaces” mucous layer in amniotes.

29. Lissamphibian Integument
Multicellular mucous glands
Multicellular poison glands
Stratum
corneum
(thin)
Epidermis
Dermis
Mucous gland
Poison gland

30. Amniote Integument
Thick stratum corneum (no mucus) - Primary barrier to water loss and infection.
Epidermal derivatives made of keratin: epidermal scales, hair, feathers

31. Reptile Integument
Epidermal scales = thickened stratum corneum separated by thinner areas of stratum corneum
can be “tiled” or overlapping.

32. Avian Reptile Integument
Epidermal scales on legs & feet
Feathers = modified epidermal scales (with dermal pulp cavity)
Few multicellular glands

33. Mammalian Integument Epidermal scales LOST
Hair = keratinous epidermal outgrowth (with dermal pulp cavity)
Sweat glands = coiled, produce watery sweat for cooling or traction. (Scent glands) = modified sweat glands
Sebaceous glands = associated with hair follicles, produce sebum.
These form by sinking of regions of epidermis into the dermis.

34. Mammalian Integument Stratum corneum Epidermis Hair Sebaceous gland
Sweat

35. Mammalian Hair

36. Mammalian Integument
Mammary glands = produce milk for nourishment of young...
derived from sweat and/or sebaceous glands.
Nipple
Teat
cistern
Monotremes lack nipples.

37. Vertebrate Miscellaneous
Keratinous claws, nails, or hooves (Tetrapoda)
Keratinous beaks (Aves & Testudinea)
Shell plates (Testudinea & armadillos) = dermal bone & keratinous sheets
Horns (various amniotes) = dermal bone & keratinous sheath
Antlers (cervid mammals) = dermal bone (shed yearly)

38. Reptilian Keratinous Beaks

39. Amniote “Shells” of Dermal Bone

40. Horns and Antlers

41. Subphylum Vertebrata Chondrichthys Actinopterygii coelacanths
amphibians
hagfishes
lungfishes
lampreys
Mammalia
Reptilia *
thick
stratum
corneum,
mucus
layer lost
stratum
corneum
* epidermal scales of beta keratin

42. Amniota lizards & snakes crocodilians montremes marsupials eutherians
turtles
lizards & snakes
crocodilians
birds
beak,
shell
plates
nipples
hair;
sweat, sebaceous,
& mammary glands
feathers,
beak
epidermal
scales of beta keratin

43. Teeth Teeth formed by the epidermis & dermis.
Thought to be derivatives of “placoid” scales around mouth.
Epidermis contributes enamel.
Neural crest cells in dermis contribute dentin and constitutes some of the pulp cavity.

44. Tooth Development
Enamel organ = epidermis that sinks into dermis, ameloblasts make enamel.
Dermal papilla = dermis surrounded by enamel organ, odontoblasts make dentine.
- primarily of neural crest cells.

45. Chondrichthyan Teeth
Revolver Dentition = teeth develop further back in the mouth and as they mature move to the crest of the bone.
Eventually fall out.
teeth in
use
developing
teeth

46. Tooth Terms Homodont = all teeth similar.
Heterodont = teeth that differ.
Polyphyodont = teeth replaced continually throughout life.
Diphyodont = teeth replaced once in life (2 sets of teeth) Mammals

47. Subphylum Vertebrata Chondrichthys Actinopterygii coelacanths
amphibians
hagfishes
lungfishes
lampreys
Mammalia
Reptilia
revolver
dentition
heterodont,
diphyodont
teeth

48. Mammalian Teeth Anterior to Posterior
Incisors = flattened teeth, 1 cusp.
Canines = conical teeth, 1 cusp.
Premolars = multicusped teeth, present in both first and second sets of teeth.
Molars = multicusped teeth, present only in second set of teeth.

49. Incisors-canines-premolars-molars
Mammalian Teeth
Diastema = space between teeth.
Dental Formula = Count of tooth types in one half of a mammal jaws.
Incisors-canines-premolars-molars
upper first, lower jaw second.
Human = /
Dog = /
Mule deer = /

50. Human Teeth