BIOLOGY 453 - COMPARATIVE VERT. ANATOMY WEK 2, Lab 3 - Anamniote Skin GOALS 1. Recognize the skin of these anamniotes (vertebrates that lack amniotic egs): shark, ray-fined fish & amphibians. 2. Know these Clades: Gnathostomata, Tetrapoda 3. Know the germ layer origin of each skin derived layer or structure noted in the introduction. 4. Identify these layers of the skin in al slides (as present): epidermis: stratum corneum, stratum basalis & dermis. 5. Identify these dermal structures: dermal papilae & dermal scales. 6. Identify tisues: epithelial, lose conective tisue, dense conective tisue, skeletal muscle tisue, cartilage & bone. 7. Identify these types of dermal scales: placoid, ganoid & elasmoid (which includes ctenoid & cycloid). 8. Identify these exocrine glands: unicelular, multicelular mucous & multicelular granular (poison). 9. Identify chromatophores. Specimens to Examine Type of Material Specimens whole, preserved specimens shark, gar, salmon, perch, frog, toad & salamander dried shark skin, ganoid, cycloid, ctenoid scales lucite blocks fish scales (includes shark, ganoid, cycloid & ctenoid) microscope slides shark skin, teleost (bony fish) skin, frog/Rana skin cros-sections, & frog skin showing pigment cels 35 m slides frog skin (low & high power) Aditional Sources of Information Skin Topic Layers Shark Ray-fined bony fish Amphibian Liem et al. pg. 208-21 21, 215-216 21-216 217 Fishbeck & Sebastiani pg. 29, 126-127 30 3, 214-216 Chondrichthyes (Shark) Skin Cavanihac, J-M. 207. Fishes & Scales. Microscopy-UK. htp:/ww.microscopy-uk.org.uk/mag/indexmag.html?htp:/ww.microscopy-uk.org.uk/mag/artjan02/fishes.html McGrouther, M. 206. About Fishes: Placoid scales. Australian Museum Fish Site htp:/ww.amonline.net.au/fishes/what/scales/placoid.htm Millen, S. 203. Lab 2: The Integument & its derivatives. Biol. 204. Univ. of British Columbia. htp:/ww.zology.ubc.ca/courses/bio204/lab5_frameset.htm Univ. of Alberta. 199. Bio. 25. Shark skin X-section. htp:/ww.biology.ualberta.ca/courses.hp/zo.25/squaluskinx-sect.jpeg Actinopterygi (Bony Fish) Skin McGrouther, M. 206. About Fishes: Fish Scales. Australian Museum Fish Site. htp:/ww.amonline.net.au/fishes/what/scales/index.htm National Conservation Training Center. 208. Normal Trout Histology. USFWS Lok at Integument & bone. htp:/training.fws.gov/trout_histology/ UC - Davis, Teaching Resource Center. 202. The Skin. Anatomy, Physiol. & Cell Biol. 10. Fish, skin - mucous cells (LM, Medium): htp:/trc.ucdavis.edu/mjguinan/apc10/modules/Integument/skin/mucous/mucous.html Fish, skin - alarm cells (LM, Medium): htp:/trc.ucdavis.edu/mjguinan/apc10/modules/Integument/skin/alarm/alarm.html Fish, scales (Gros, High): htp:/trc.ucdavis.edu/mjguinan/apc10/modules/Integument/hair/scales2/scales.html Fish, scales (LM, Medium): htp:/trc.ucdavis.edu/mjguinan/apc10/modules/Integument/hair/scales3/scales.html Fish scles (EM, Low): htp:/trc.ucdavis.edu/mjguinan/apc10/modules/Integument/hair/scales4/scales.html Virginia-Maryland Regional College of Veterinary Medicine. 201. Atlas of Fathead Minnow Normal Histology. Univ. of Maryland. htp:/aquaticpath.umd.edu/fhm/skin.html Lisamphibia (frog, salamander) Skin Developmental Biology Online. 204. Development of the Integument. Cell & Developmental Biology. Dept. of Zology, Univ. of Guelph htp:/ww.uoguelph.ca/zology/devobio/210labs/ecto5.html King, D. 202. Epithelium & Gland: Frog Skin. Southern Illinois University Schol of Medicine. htp:/ww.siumed.edu/~dking2/intro/IN031b.htm Meredith, H. 208. X-Frogs. EDGE (Evolutionarily Distinct & Globally Endangered) Blog., Zological Society of London. htp:/ww.edgeofexistence.org/edgeblog/?p=676 Univ. of Alberta 199. Frog Skin X-section. Bio. 25 htp:/ww.biology.ualberta.ca/courses.hp/zo.25/frogskinx-sect.jpeg Clades & Taxonomy Subphylum Craniata/Vertebrata Clas Chondrichthyes: sharks, skates, rays, ratfish. Clas Actinopterygi: ray-fined fish Clas Lisamphibia: frogs, salamanders, caecilians Clade Gnathostomata: sharks, bony fish, tetrapods, etc. Shared derived traits: bone or cartilage suports for the jaws Clade Tetrapoda: amphibians, & amniotes Shared derived traits: keratinized epidermis Introduction to Vertebrate Integument Epidermis Germ Layer: ectoderm Functions: forms surface of skin, exocrine glands & keratinized structures. Design or Tisue: epithelial; cels atach to other cels, forming thin or thick layers or single rows of cels. Cel shapes: flat - squamous, square - cuboidal, tal - columnar. Major Layers or Divisions of Epidermis: Stratum corneum (Only tetrapods): Hardened, keratinized dead cels on surface of epithelium Stratum basalis (germinativum) (Al vertebrates): Basal layer, mitoticaly active cels (i.e. "germinal") Cels are usualy larger, taler than cels above this layer Some cels diferentiate & migrate upward Keratinized, Special Structures in Tetrapods: Epidermal scales, tubercles or pads on fet, claws, nails, hoves; other features: hair, feathers, quils, and horns. Exocrine Glands Origin: Primitive types are single cels in epidermis. Larger, multi-celular glands made of epidermal cels sink below surface of skin & secrete products via a duct to the surface of the skin. Types: mucous, granular, apocrine & ecrine sudoriferous, uropygial, femoral, sebaceous, mammary Dermis Germ Layer: mesoderm &/or ectomesenchyme (neural crest) Design: Conective tisue with scatered cels surounded by extracelular protein fibers - elastic, colagen etc. Lose conective tisues are usualy more vascularized with fewer fibers. Also caled stratum spongiosum. Dense conective tisues have more colagen fibers & form tough, durable, thick layer. Caled s. compactum. Dermal Papilae Uper layer of dermis forms finger-like projections below epidermis. Highly vascular, lose conective tisues form the nutritive base for the epidermis or epidermal derivatives. The papilae induce formation of epidermal features, e.g. hair, feathers. Dermal Scales Composition: Variable; se descriptions below Germ Layers: enamel (ectoderm), dentine (neural crest), bone (mesoderm) Placoid scales: sharks Design: tiny, sharp projectiles that stick up through epidermis. Composition: enamel, dentine & bone. Ganoid scales: primitive Actinopterygians fishes, e.g. gar Design: diamond or rhomboid shaped, non-overlaping Composition: enameloid surfaces & thick bone Elasmoid scales: most living Actinopterygians & living Sarcopterygians Design - highly overlaping; includes both cycloid & ctenoid types Composition: thin, flexible fibrous bone. Osteoderms Dermal scales sink deper into the dermis in some tetrapods. Largest ones are found in the turtle's & the armadilo's bony shels. Chromatophores Germ Layer: neural crest (ectomesenchyme) Function: skin color, hair & feather coloration (pigmentation) Melanophores/melanocytes produce a brown/black pigment. Often at the dermal-epidermal boundary Anamniotes: pigment is mobile within long branching cels alowing color changes Amniotes: branched melanocytes inject pigment into epidermal cels Orientation These slides & materials do NOT represent al skin structures that exist in these taxa. Checklists represent ONLY what we have available & can find easily!! Integument layers & scales are very thin & may tend to pul or tear apart on slides. Glands may be sen but exit ducts are often harder to find because skin sections are so thin. More rarely you may se the duct but not the conection to the exocrine gland. Orient yourself first by studying the ilustrations. Use only 4X, 10X or 40X to se features in ANY slide. Clas Chondrichthyes (Sharks, skates, rays, ratfish) Whole Shark Skin: dried pieces & in lucite blocks Identify individual placoid scales under a disecting scope. Be able to identify this as the skin of a shark. Section of a dogfish shark?s skin as sen from the surface, showing numerous microscopic placoid scales. This section is made parallel to the skin surface, so it cuts through the protruding placoid scales. Visible in some microscope slides. Microscope Slide: Dogfish/Squalus Skin Older slides may be drying out around the edges, but the center sections are fine to study. These slides were made using several diferent stains to diferentialy color muscle tisue, epidermis & conective tisue, so the detail is amazing. Identify these layers - epidermis, dermis. Identify these structures - placoid scales, chromatophores (a few in some slides) & unicelular glands. Identify these tisues - epithelial tisue, lose conective tisue, dense conective tisue, and skeletal muscle. Smal cartilaginous spines may be visible within the skeletal muscle tisue on some of the newer slides. od ? dermal papila (pulp cavity inside scale), de ? dentine of placoid scale, ep ? epidermis, d ? dermis (lose conective tis.), dense conective tis. at base & unicelular glands (open circles). Shark Skin section at low power: 1 = skeletal muscle, 2 = dense conective tis., 3 = lose conective tis., 4 = epidermis. Find placoid scales & chromatophores. Shark skin section at high power: Label these in this image: epidermis, dermis, pulp cavity of placoid scale, placoid scale, chromatophore, unicelular gland 2 1 3 4 Clas Actinopterygi (Ray-fined fishes) Intact fish scales, dried or wet or in Lucite block. May have chromatophores & skin stil atached. Ganoid Scales Gar Skin Individual Ganoid Scales Elasmoid Scales: Cycloid Type Elasmoid Scales: Ctenoid Type Tiny ?hoks? or cteni on exposed side. Microscope Slide: Bony Fish/Teleost skin Identify these layers - epidermis, dermis. Identify these structures - unicelular mucous glands, elasmoid scale (below epidermis) chromatophores/melanophores. Identify these tisues - epithelial tisue, dense conective tisue, and skeletal muscle. Smal bony ribs may be visible in some slides near the botom of the muscle tisue. Bony Fish Skin low power: 10 - bone tisue, 7 - skeletal muscle tisue, 5 - elasmoid scale & 1 - epidermis Most of our slides lack chromatophores. Labeled Fish Skin at high power: 1, 3 - epidermis, 2 & 4 unicelular glands (2 - mucous gland, 4 - alarm or club gland), 5 ? elasmoid scale, 6 ? dermis (dense con. tisue), 7 - skeletal muscle tis. 8 ? chromatophore, 9 - RBCs. Exposed side Exposed side Hidden portion 1 10 7 5 Clas Lisamphibia (Frogs, Salamanders & Caecilians) Demo Table: Preserved True Toads & Spadefot Toads Remove a toad or salamander from one of the jars & lok for these superficial structures on the skin: Poison Glands: Large parotid glands are behind eye in some specimens (its just a region with a high concentration of the poison glands). Poison glands may be scatered evenly or concentrated in smal areas causing bumps or thicker-loking regions of the skin. Tubercles: smal, black (heavily keratinized) pads on fet aid traction. Lok at the toad specimens that have 2 large brownish tubercles on its back fot. Other tubercles: Many amphibian males develop blackish/brown patches of keratinized tisue on their thumbs, arms or even chest to hold females during mating. This tailed frog is a god example. Spades: Spadefot toads have a black "spade" on their hind fet for burowing (diging). The spade is heavily keratinized. Rana pigment cels (chromatophores) Microscope Slides Identify chromatophores (i.e. melanophores) sen from dorsal views. These large cels have numerous, finger-like branches. The pigment may be concentrated in the center or widely scatered acros al branches of a cel. The skin loks darkest when the pigment is most widely dispersed. Chromatophores Low power view of frog skin (surface view). Parotid Gland Frog skin, diagram Frog Skin, 35 m Slide (Low Power) Stratum spongiosum (laxum) = lose conective tisue Stratum compactum = dense conective tisue Frog/Rana Microscope Slides: low power views with more dermis visible Label the layers: epidermis, s. corneum (peling lose), s. basalis, and dermis. Label the structures: granular (poison) glands, multicelular mucous glands, and chromatophores. Label the tisues: epithelial & dense conective tisue (Hard to se ?lose? conective tisue in this view). Frog/Rana Microscope Slides: Mucous Glands Mucous glands tend to have a ?fibrous? or thready lok. Frog/Rana Microscope Slides: Poison glands Poison glands may be large, as below, but some are smal. They contain bright, pink-staining granules. The very dark pink cels are probably the epithelial cels forming the wal of a poison gland. Karen Microsoft Word - 453lab3-09.doc
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