Comparative Anatomy Integument Note Set 6 Chapter 6

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

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

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.

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.

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

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.

Figure 8.8: Derivatives of primitive dermal bone.

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

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

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

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

(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

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.

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

Modes of Secretion Merocrine Holocrine Apocrine Figure 8.15

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.

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

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

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.

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

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.

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.

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

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.

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

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.

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.

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

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.

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

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

Literature Cited Figure 8.1- http://www.homestead.com/doctorderm/skinanatomy.html Figure 8.2- http://www.allercafoundation.org/animal16.html Figure 8.3 & 8.29- Kardong, K. Vertebrates: Comparative Anatomy, Function, Evolution. McGraw Hill, 2002. Figure 8.4- http://markmlucas.com/Amphibgallery%20frogs.htm Figure 8.5- http://www.exn.ca/Stories/1998/05/22/58.asp Figure 8.6- http://people.eku.edu/ritchisong/342notes1.htm Figure 8.7- http://www.amonline.net.au/fishes/what/scales/ Figure 8.8, 8.12 & 8.26- Kent, George C. and Robert K. Carr. Comparative Anatomy of the Vertebrates. 9th ed. McGraw-Hill, 2001. Figure 8.9- http://people.eku.edu/ritchisong/342notes2.htm Figure 8.10 & 8.11- http://www.mhhe.com/biosci/ap/histology_mh/glands.html Figure 8.13 (a)- http://www.invasiveplants.net/images/j2.jpg Figure 8.13 (b)- http://www.batraciens-reptiles.com/page-salamandres.htm Figure 8.14- http://www.caudata.org/cc/articles/sexing.shtml#glossary Figure 8.15- http://pharma.kolon.co.kr:8080/test/newstopic/main_contents.jsp?seq=241&no=583

Literature Cited Figure 8.16 & 8.17- http://www.mhhe.com/biosci/ap/histology_mh/glands.html Figure 8.18- http://www.richard-seaman.com/Reptiles/Usa/PhotoGalleries/ Figure 8.19- http://science.howstuffworks.com/alligator2.htm Figure 8.20- http://www.palaeos.com/Vertebrates/Units/Unit200/300.html Figure 8.21 (a)- http://museum.gov.ns.ca/mnh/nature/snakes/sfacts.htm Figure 8.21 (b)- http://www.biosbcc.net/ocean/marinesci/05nekton/mtintro.htm Figure 8.22- http://www.sdsnake.com/Rat.htm Figure 8.23- http://www2.worldbook.com/features/reptiles/html/body_senorg.html Figure 8.24- http://www.zoo.ufl.edu/courses/vertzoo/lab_birds.html Figure 8.25- http://www.seaworld.org/infobooks/HarborSeal/hssenses.html Figure 8.27- http://trc.ucdavis.edu/mjguinan/apc100/modules/Integument/horn/horn1/horn.html Figure 8.28- http://trc.ucdavis.edu/mjguinan/apc100/modules/Integument/horn/antler1/antler.html