Lecture_8_-_Integument

In osteicthyes with bony ganoid scales eg gar bowfin

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Unformatted text preview: om ostracoderm armour (cosmoid scales). In Osteicthyes with bony (ganoid) scales, e.g., gar, bowfin, the dentin layer is missing. In teleosts, both the enamel and dentin are missing, and only bone with no apatite and lots of collagen remains. In shark scales (dermal denticles or placoid scales) all three layers remain. Fish Integument as seen in teleosts The epidermis is generally thin and well supplied with unicellular mucous glands (club cells). The scale is in the dermis. Recall that the dermis can produce bone, but the epidermis never does. KK 6.10, H&G 6.2 Elasmoid scale from a mature Atlantic Salmon. Fisheries biologists can use such scales to determine the fish’s age, when it went to sea, and how many times it has returned to spawn. Amphibian Integument Amphibian integument is like that of fish, but poison glands are common and there are no scales. Many poisonous forms are brightly coloured with chromatophores. KK 6.12, H&G 6.7 Reptile Integument KK6.12, H&G 6.8 There are no mucous glands in amniotes, although scent glands may be present. Scales are epidermal, not dermal, and are keratin rather than bone. They are not homologous with fish scales Snake Skin Larger scales on the ventral surface of snakes or over dermal bones in turtles and crocodiles, are called scutes. De...
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