IntegumentSkin = composite organ

Epidermis = superficial; epithelial tissue; ECTODERMAL

Dermis = deep; connective tissue; mostly MESODERMAL

Neural Crest Cells = migrate into both epidermis and dermis; ECTODERMAL

Epidermis = generalized ectoderm + neural crest (pigment cells)

Dermis = dermatomal mesoderm + scattered neural crest cells

Vertebrate Integument Devel.

Vertebrate Embryo (section)

gut

coelom

dermatome

vertebra

myotome

epidermalectoderm

developingskin

dermis

epidermis

neural crest

Cephalochordate IntegumentEpidermis = 1 cell layer (simple epithelium)

Dermis = compact alternating layers of collagen with fibroblasts

NO neural crest

EPIDERMIS

DERMIS

Mucus

Basal lamina

Vertebrate/Craniate Skin Stratified epidermis (= an epithelium)

Stratum basale (Basal Layer) = deep layer, contacts the basal lamina, mitotically activeKeratin = proteins in superficial epidermis (keratinocytes); “harden” = cornifiedStratum 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

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.

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.

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)

Human Integument

Epidermis

Dermis

Stratumcorneum

Hair

Sebaceousgland

Sweatgland

Human Hair & Gland Devel.

Human Mammary Ridge and Mammary Glands

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

Human Mammary Development Mammary Glands,

single pair with nipples, fat and glandular tissue.

Supernumary (ectopic) nipples form along developmental “milk” line.

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).

Human Skin Problems/DiseasePimples form when a hair follicle is

blocked and sebum builds up.

Skin Cancer

most common – basal cell carcinoma

most dangerous - melanoma

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

Dermal Bone Growth

Dermal (Bony) ScalesEpidermis 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

Dermal Scales

Epidermal

Dermal

Acellular

Cellular

Acellular or Cellular

Enamel

Dentine

Lamellar Bone

Vascular Bone

Integumentary GlandsEpidermal; 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

Hagfish & LampreysKeratinous (epidermal) “teeth”

No dermal or epidermal scales.

Petromyzontid Integument

Epidermis

Dermis(stratumcompactum)

Basal layer

Ammocoete larva

Basal lamina

Placoid ScalesSynapomorphy of chondrichthyans

Enamel (superficially), Dentin (deep)

Scale “erupts” from epidermis.

Central dermal pulp cavity.Enamel

Dentin

Pulpcavity

Ganoid ScalesFound in reedfishes, gars, and fossil

sturgeon and bowfin

Enamel (superficially), Lamellar bone (deep), lack a pulp cavity

Scale “erupts” from epidermis.

Teleost ScalesLamellar bone ONLY

Scale covered by epidermis.

Cycloid or Ctenoid (with projections)

Craniata

hagfis

hes

lam

preys

Chondrichth

ys

Actin

optery

gii

coel

acan

ths

lungfis

hes

amphib

ians

Mam

mal

ia

Reptil

ia

stratified epidermis

Subphylum Vertebrata

hagfis

hes

lam

preys

Chondrichth

ys

Actin

optery

gii

coel

acan

ths

lungfis

hes

amphib

ians

Mam

mal

ia

Reptil

ia

placoidscales

ganoidscales

dermal bone; dermal stratum laxum

dermalscaleslost

sturg

eons

&

paddle

fishes

gars

Amia

(the

bowfin)

TELEOSTS

reed

fishes

Class Actinopterygii

cycloid orctenoidscales(enamel lost)

ganoid scales

Tetrapod IntegumentStratum corneum =

superficial layer of dead keratinocytes (outer epidermis)

prevents water loss; protects- thin, underlies mucous layer in lissamphibians.

- thick, “replaces” mucous layer in amniotes.

Lissamphibian Integument

Epidermis

Dermis

Multicellular mucous glands

Multicellular poison glands

Mucous gland Poison gland

Stratumcorneum(thin)

Amniote IntegumentThick stratum corneum (no mucus) -

Primary barrier to water loss and infection.

Epidermal derivatives made of keratin: epidermal scales, hair, feathers

Reptile IntegumentEpidermal scales = thickened stratum

corneum separated by thinner areas of stratum corneum

can be “tiled” or overlapping.

Avian Reptile IntegumentEpidermal scales on legs & feet

Feathers = modified epidermal scales (with dermal pulp cavity)

Few multicellular glands

Mammalian IntegumentEpidermal 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.

Mammalian Integument

Epidermis

Dermis

Stratumcorneum

Hair

Sebaceousgland

Sweatgland

Mammalian Hair

Mammalian IntegumentMammary glands = produce milk for

nourishment of young...

derived from sweat and/or sebaceous glands.

NippleTeat

cisternMonotremes lack nipples.

Vertebrate MiscellaneousKeratinous 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)

Reptilian Keratinous Beaks

Amniote “Shells” of Dermal Bone

Horns and Antlers

Subphylum Vertebrata

hagfis

hes

lam

preys

Chondrichth

ys

Actin

optery

gii

coel

acan

ths

lungfis

hes

amphib

ians

Mam

mal

ia

Reptil

ia

stratumcorneum

thickstratumcorneum,mucus layer lost

* epidermal scales of beta keratin

*

Amniota

montre

mes

mar

supia

ls

euth

eria

ns

turtl

es

lizar

ds & s

nakes

croco

dilian

s

birds

feathers,beak

beak,shellplates

epidermalscales of beta keratin

hair;sweat, sebaceous,& mammary glands

nipples

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.

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.

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 inuse

developingteeth

Tooth TermsHomodont = all teeth

similar.Heterodont = teeth that

differ.Polyphyodont = teeth

replaced continually throughout life.

Diphyodont = teeth replaced once in life (2 sets of teeth). - Mammals

Subphylum Vertebrata

hagfis

hes

lam

preys

Chondrichth

ys

Actin

optery

gii

coel

acan

ths

lungfis

hes

amphib

ians

Mam

mal

ia

Reptil

ia

heterodont,diphyodont

teeth

revolverdentition

Mammalian TeethAnterior 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.

Mammalian TeethDiastema = 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 = 2-1-2-3 / 2-1-2-3

Dog = 3-1-4-2 / 3-1-4-3

Mule deer = 0-0-3-3 / 3-1-3-3

Human Teeth

2 - 1 - 2 - 3