1/21/09 Notes - 1/21/09 Tripoblastic animals: 3 primary...

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1/21/09 Tripoblastic animals: 3 primary germ layers 1. Outer layer: ectoderm a. Epidermis b. Nervous system c. Lining of mouth and anus 2. Inner layer: endoderm a. Lining of the gut: liver and lungs 3. Middle layer: mesoderm a. Bones, muscles, heart, kidneys Occurrence and Importance of Mesoderm Jellyfish, cnetophore (comb jellies o Diploblastic, 2 layers. No meso. Flatworms (Planaria) and rest of phyla o Triploblastic, 3 layers Mesoderm forms during embryology as: a. An outpouching of the gut ( deuterostomes ) May be modified b. Cells that are set aside early ( protostomes) Deuterostomes: Amphioxus Hemichordates Tunicates Echinoderms Craniatas: lamprey, fish, amphib, reptiles, birds, mammals Protostomes: Worms, molluscs, insects, lobsters, tapeworms, roundworms
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Coelom: space surrounded by mesoderm o Why helpful: makes it possible for food to move through the digestive system Heterochrony: a genetic shift in the timing of the development of a body
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This note was uploaded on 02/14/2009 for the course ZOL 328 taught by Professor Hill during the Spring '08 term at Michigan State University.

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1/21/09 Notes - 1/21/09 Tripoblastic animals: 3 primary...

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