Comparative AnatomyComparative AnatomyIntegumentIntegument

Kardong Kardong Chapter 6Chapter 6

Part 8Part 8

IntegumentIntegument

Epidermis derived from Epidermis derived from ectodermectoderm Gives rise to glands Gives rise to glands

Dermis derived from Dermis derived from mesodermmesoderm

Figure 8.1.

Figure 8.3. Amphibian skin showing mucous and poison glands.

Figure 8.2. Poisonous Dart Frog.

ModificationsModifications

Presence or absence of Presence or absence of bone in dermisbone in dermis

Glands in aquatic formsGlands in aquatic forms Specializations in epidermis Specializations in epidermis

of land dwellersof land dwellers

Figure 8.4. African hairy frog with specialized hairs acting as auxiliary respirator organs.

Functions of the Skin Functions of the Skin

ProtectionProtection RespirationRespiration Temperature ControlTemperature Control Nourishment of YoungNourishment of Young Locomotion and Locomotion and

reproductive structuresreproductive structures

Figure 8.5. African clawed frog (Zenopus laevis) was used for pregnancy test and spread chytrid

fungus around the world.

Fish SkinFish Skin No stratum corneumNo stratum corneum Many unicellular glandsMany unicellular glands

Like goblet cells, Like goblet cells, secretes mucussecretes mucus

Photophores in deep-sea Photophores in deep-sea fishes fishes

Figure 8.6.

Dermal Scales Dermal Scales Dermal bone plates Dermal bone plates

became skull surface bonesbecame skull surface bones Ancient armorAncient armor

Rhomboid scalesRhomboid scales Modern fishModern fish

Cycloid and ctenoid scalesCycloid and ctenoid scales Placoid and ganoid scalesPlacoid and ganoid scales

Figure 8.8. Cycloid, ctenoid, placoid, and ganoid scales of modern fish.

Figure 8.7. Ostracoderm.

Figure 8.9. Derivatives of primitive dermal bone.

Dermal Scales (cont.’d)Dermal Scales (cont.’d)

Ctenoid scalesCtenoid scales Growth rings or annuliGrowth rings or annuli

No epidermal scalesNo epidermal scales Scales are dermalScales are dermal

Figure 8.10.

Amphibian SkinAmphibian Skin Loses dermal scalesLoses dermal scales

Exception: Caecilians and some primitive frogsException: Caecilians and some primitive frogs Epidermal multicellular glands abundantEpidermal multicellular glands abundant Stratum corneum (contains Leydig cells to resist entry of Stratum corneum (contains Leydig cells to resist entry of

bacteria and viruses)bacteria and viruses)

Fig. 8.11. (book fig. 6.12).

Integumentary Gland Type Integumentary Gland Type

Simple tubularSimple tubular Plethodontid mental glands associated with Plethodontid mental glands associated with

courtshipcourtship Simple coiled tubularSimple coiled tubular

Sweat glandsSweat glands Simple branched tubularSimple branched tubular

Female plethodontid- spermathecaFemale plethodontid- spermatheca Simple alveolar (acinar)Simple alveolar (acinar)

Mucous glandsMucous glands

Figure 8.12.

Compound tubularCompound tubular Mammary glands of monotremesMammary glands of monotremes

Compound branched alveolarCompound branched alveolar Mammary glands of placentalsMammary glands of placentals Courtship glandsCourtship glands

Figure 8.13.

(a) Simple tubular, (b) Coiled tubular, (a) Simple tubular, (b) Coiled tubular, (c) Simple branched tubular, (d) Compound tubular, (c) Simple branched tubular, (d) Compound tubular, (e) Alveolus of simple saccular gland, (f) Simple branched saccular, (e) Alveolus of simple saccular gland, (f) Simple branched saccular, (g) Compound alveolar(g) Compound alveolar

Figure 8.14. Morphological varieties of multicellular glands.

Plethodontid Salamanders - MatingPlethodontid Salamanders - Mating Internal fertilizationInternal fertilization Male: mental glands on chin, cloacal glands Male: mental glands on chin, cloacal glands

to form spermatophore, and caudal to form spermatophore, and caudal courtship glandscourtship glands

Female: spermatheca for sperm storageFemale: spermatheca for sperm storage Glands secrete pheromonesGlands secrete pheromones

Figure 8.16. (a) Plethodon (b) spermatophore.

(a)

(b)Figure 8.15. Salamander spermatophore (book figure 14.40).

Glands Associated with MatingGlands Associated with Mating

Figure 8.17. (a) mental glands, (b) cloaca, (c) nasolabial groove.

(a) (b)

(c)

Skin Glands in a SalamanderSkin Glands in a Salamander

Cloacal Glands in a Salamander

Head Glands in a Salamander

Modes of Secretion Modes of Secretion

MerocrineMerocrine HolocrineHolocrine ApocrineApocrine

Figure 8.18. Mammalian skin.

MerocrineMerocrine Cell body not injuredCell body not injured Release particles by exocytosisRelease particles by exocytosis Most sweat glands in mammalsMost sweat glands in mammals

HolocrineHolocrine Cell body discharged with Cell body discharged with

contentscontents Whole cell diesWhole cell dies Sebaceous glandsSebaceous glands

Figure 8.19. (a) merocrine and (b) holocrine glands.

(a)

(b)

ApocrineApocrine Cellular products gather on Cellular products gather on

surface then pinched offsurface then pinched off Apical portion pinched offApical portion pinched off Axillary sweat glands Axillary sweat glands

Figure 8.20. Apocrine gland.

Reptile Skin Reptile Skin

Few glands (dry skin)Few glands (dry skin) Thick stratum corneum Thick stratum corneum

with modificationswith modifications EpidermalEpidermal scales scales

Figure 8.21. Desert horned lizard.

Some reptiles have Some reptiles have remnants of dermal remnants of dermal armor (osteoderms)armor (osteoderms) Osteoderms beneath some Osteoderms beneath some

epidermal scalesepidermal scales Gastralia- large Gastralia- large

osteodermsosteoderms Alligator and skinksAlligator and skinks

True dermal bonesTrue dermal bones TurtlesTurtles

Figure 8.22. Osteoderms (dermal plates) of alligator.

Turtles Turtles Shell of dermal boneShell of dermal bone Carapace (shell) – dorsalCarapace (shell) – dorsal Plastron- ventralPlastron- ventral

Mesoplastron additional bone on Mesoplastron additional bone on primitive, extinct turtlesprimitive, extinct turtles

Nuchal- diagnostic boneNuchal- diagnostic bone

Figure 8.23. Turtle shell.

Reptile SkinReptile Skin

Turtles have epidermal Turtles have epidermal scutes- large epidermal scutes- large epidermal scalesscales

Snakes have scutes on bellySnakes have scutes on belly Spikes and spines are Spikes and spines are

epidermalepidermal

Figure 8.24. Snake belly scutes (a) and white bony plate of turtle with scutes removed.

(a)

(b)

Reptile Integumentary GlandsReptile Integumentary Glands Femoral pores Femoral pores

Occur ventrally, waxy Occur ventrally, waxy excretionexcretion

Many lizards and snakes Many lizards and snakes have scent or cloacal have scent or cloacal glandsglands Snakes use forked tongue Snakes use forked tongue

to pick up scent to pick up scent (Jacobson’s organ)(Jacobson’s organ)

Figure 8.25. Prairie Rattlesnake.

Figure 8.26. Jacobson’s organ.

Musk GlandsMusk Glands Scent glandsScent glands Along carapace in turtlesAlong carapace in turtles

- Rathke’s glands - Rathke’s glands Under lower jaw in crocodilesUnder lower jaw in crocodiles Musk deerMusk deer

Take secretions to make perfume Take secretions to make perfume

Fig. 8.27. TurtleRathke’s glands.

Skin of Birds Skin of Birds Few epidermal scalesFew epidermal scales

Legs and beak Legs and beak Dermal scales are absentDermal scales are absent Claws- diversifiedClaws- diversified Few glandsFew glands

Uropygial gland- Uropygial gland- preening glandpreening gland

Dermal scales absentDermal scales absent

Figure 8.28. Feather type (see book figure 6.15).

Feathers Feathers Modification of reptilian scalesModification of reptilian scales 3 types3 types

Contour- flight featherContour- flight feather provides wing shapeprovides wing shape

Down- beneath contourDown- beneath contour featherfeather

Filoplume- long shaftFiloplume- long shaft lost its vanelost its vane

Figure 8.29.

Skin of Mammals Skin of Mammals Modifications of stratum corneumModifications of stratum corneum

Hair, claws, nails, hoovesHair, claws, nails, hooves HairHair

Like filoplume feather and Like filoplume feather and lack detaillack detail

VibrissaeVibrissae Specialized hairsSpecialized hairs Tactile in functionTactile in function Figure 8.30. Vibrissae of harbor seal.

Skin of Mammals (cont’d.)

Figure 8.31. Cross sections of mammalianskin.

Cornified StructuresCornified Structures

Baleen PlateBaleen Plate Toothless whale’s horny Toothless whale’s horny

sheets of oral ectodermsheets of oral ectoderm Not boneNot bone Used for filter feedingUsed for filter feeding

Tori padsTori pads Epidermal padsEpidermal pads

Figure 8.32. Products of stratum corneum; tori.

HornsHorns HornsHorns

In bovid familyIn bovid family Outgrowth of dermal Outgrowth of dermal

corecore Unbranched Unbranched Covered by epidermal Covered by epidermal

horny, keratinized horny, keratinized sheathsheath

PermanentPermanentFigure 8.33. Bovine horn.

AntlersAntlers

Antlers and horns of Antlers and horns of giraffegiraffe DeerDeer Dermal bonesDermal bones Dermal bone of antler Dermal bone of antler

attaches to skull boneattaches to skull bone Shed annuallyShed annually Outside layer is highly Outside layer is highly

vascularizedvascularized

Figure 8.34. Antler.

Figure 8.35. (a) horns and (b) antlers Figure 8.35. (a) horns and (b) antlers (see book figure 6.26).(see book figure 6.26).

Dermal Pigments Dermal Pigments

ChromatophoresChromatophores contain pigment granulescontain pigment granules Melanophores (brown)Melanophores (brown)

Melanin granules within melanosomes Melanin granules within melanosomes Lipophores (yellow and red)Lipophores (yellow and red) Iridophores or guanophores (iridescent)Iridophores or guanophores (iridescent)

- - Contain reflective guanine crystals Contain reflective guanine crystals