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Topic 13: Integument

� What is skin used for?

� What does generic skin look like?

� Development, structure, derivatives, coloration

� How do skin derivatives develop?

� What are specializations seen in different taxa?

� Fishes, Amphibians, “Reptiles”, Birds, Mammals

� What is the evolutionary history of integumentary

derivatives?

What is skin used for?

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What does generic skin look like?

� ______________

� Ectodermal

� Contains glands

� Interface with

environment

� ______________

� Mesodermal

� Elastic

� Contains nerves, sense organs, blood

vessels

Liem et al. Fig. 6-1

What does generic skin look like?

� Epidermis

� Stratum ___________� Cell division

� Stratum ___________� Keratinized, some times

dead cells

� Dermis

� Stratum ___________� Loose collagen

� Very elastic

� Stratum ___________� Dense collagen

� Tough

Liem et al. Fig. 6-1

What does generic

skin look like?

Liem et al. Fig. 6-2B; histol.chuvashia.com

� Pigment cells� Just beneath epidermis

� In external layer of dermis

� ________________� Pigment can be centralized or dispersed

� Iridiophores

� ________________

� Xanthophores

What does generic skin look like?

� Pigment cells� Can be mixed to give different colors

� Mosaic of chormatophore distribution

© www.softpedia.com

How do skin derivatives develop?

� _____________________ interactions

� Epidermis and dermis interact

� Similar formation by invagination or

evagination of dermis

� Scales

� Teeth

� Feathers

� Hair

� Mammary

glands

Kardong Fig. 6-3

Epithelial-Mesenchymal Interactions

� Development of scales and teeth

� Condensation of meshenchymal papilla in dermis

� Induces formation of epidermal ______________

� Enamel organ lays down enamel

� Enamel induces odontoblast _________________

Liem et al. Fig. 6-5

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The Skin of Fishes

� Scales are hard structures embedded in the skin

� ___________________

� = Dermal denticles

� Sharks

� Superficially in dermis

� protrude through epidermis

� Dentine + Enameloid

� ___________________

� Bony fishes

� Embedded in dermis

� Covered by epidermis

� Only bone

Liem et al. Fig. 6-6B,D

The Skin of Amphibians

� No scales

� Thick dermis

� Stratum laxum

� _____________

� _____________

� Thinner epidermis

� Permeable

� Cutaneous respiration

� Evaporative

water loss

� Gland ducts

Liem et al. Fig. 6-8

Lepidosaur Skin

� Scales are __________, not bony

� Relatively ___________

� Outer epidermal generation

� Keratinized cells superficial

� Dead cells next

� Living cells deep

� Inner epidermal generation

� Living, differentiating cells

� ___________ at _____________

� Growth

� Wound healing

� Ectoparasite removal

Liem et al. Fig. 6-9

“Reptile” Skin

� Keratinized scales

� Not bony

� Superficial

� _____________ as armor

� Dermal bones

� Not articulated

� Closely or distantly

spaced

© PJB, M Vickaryous

The Skin of Birds

Liem et al. Fig. 6-11

� Thin epidermis

� Keratinized scales

on _______________

� ______________

� Start as dermal papilla

� Barbs develop

� Dermal

� Feather sheath

� Epidermal

� Breaks, externallizing

the barbs

Feathers of Birds

� Feathers differentiate by

position and function

� ____________ feathers

� Cover body

� Flight feathers if stiff and asymmetrical

� _________ & ________

� _________ composed of interlocking barbules

� ____________ feathers

� Deep & Insulatory

� _______________

� Short, stiff bristles

� Around eyes & nostrils

� Keep dirt outLiem et al. Fig. 6-10

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Skin of Mammals

Liem et al. Fig. 6-13

� Hair

� ___________

� Growth my mitosis

at base

� Papilla

� Nerves (tactile)

� Blood vessels (nutrients)

� ______________ glands

� Lubricate and waterproof

� Dermal

� ______________ glands

� Associated with hair

� Arm pits and genitals

� Body odors

� Dermal

Hair of Mammals

© www.pantene.com, www.pantogar.com, www.spectroscopynow.com

� _________

� Dead, kearinized cells

� _________

� Fibrous & tough

� Pigmented

� ______________

� Waxy

� Water-

repellant

Hair Derivatives of Mammals

Liem et al., Figure 6-16

� Claws, nails, hooves

� ______________ and

cornified projections at end of digits

� Toughens digits

� Provides frictional gripping

� Outgrowth from nail matrix

Hair Derivatives of Mammals

Liem et al., Figure 6-17; © PJB, www.memorialuniversity.ca

� ____________

� Dermal bony core

� Keratinized layer

produced by stratum germinativum

� Permanent

� ____________

� Bony outgrowths of skull

� Covered in skin: velvet

� Deciduous

� Both involved in defense

and intrasexual contest

Mammal Gland Derivatives

� _________________

� Unknown evolutionary origin

� Develop from milk ridges

� Run axilla to groin

� Form in a diversity of locations

© cornell.edu, adam.com, redangus.com

Mammal Gland Derivatives

� Mammaries overlie muscle

� ___________ have multiple ducts

� ________ have single opening and cistern

� Ducts open into cistern

Liem et al. Fig. 6-19

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Petromyzontif.

Eutheria

Testudines

Lissamphibia

Dipnoi

Actinistia

Actinopterygii

Chondrichthyes

Metatheria

Monotremata

Aves

Crocodylia

Lepidosauria

What is the evolutionary history of integumentary

derivatives?

1. Origin of scales

2. Teeth (future lecture)

3. Cycloid scales

4. Loss of scales?

5. Mucus and granular glands overdeveloped

6. Origin of scales

7. Osteoderms

8. Feathers from scales

9. Hair

10.Mammary glands

11. Loss of functional male mammaries

Liem et al. Fig. 3-1

Feathers as an

“aptation” for flight

1. Origin of feathers

2. Origin of flight

� Why did many non-avian dinosaurs have feathers?

� ___________

� ___________

© S Yamamoto; A Musser; warforscience.org; PJB

Bambiraptor

Herrerasaurus

Archaeopteryx

Larus

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