Slide Set III SPR11

Slide Set III SPR11 - SLIDE SET IV OUTLINE Animal...

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I. Neurulation A. Introduction B. Example: neurulation 1. frog 2. chick 3. spinal column and spinal cord C. Amniote embryos 1. amniotes 2. extra-embryonic membranes a. birds, reptiles b. humans SLIDE SET IV OUTLINE Animal Development (cont’d)
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II. Morphogenic mechanisms A. Cell movement/rearrangement 1. convergent extension 2. invagination, ingression, involution (e.g., gastrulatin) 3. changes in cell shape (e.g., neurulation) B. Cytoplasmic determinants (again!) 1. overview 2. axes of symmetry in amphibians (e.g., gray crescent, cortical rotation, cell potency) 3. bicoid gene in Drosophila C. Cell communication (again!) 1. Holtfreter’s work 2. 3. induction D. Pattern formation 1. 2. SLIDE SET IV OUTLINE (cont’d.) Animal Development
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Organogenesis: continued cell movement and cell differentiatio n result in the development of organs and organ systems Example: nuerulation and the development of the central nervous system in frogs DEVELOPMENT PATTERN: 1. fertiliza., 2. cleavage, 3. gastrulation 4. organogenesis
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FROG Fig. 47.12 (7 th : 47.14) 1. Neurulation of surface ectodermal cells is induced by the underlying NOTOCORD NOTOCHORD = a skeletal rod in chordates formed from DORSAL MESODERM
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Fig. 47.12 (7 th : 47.14) 2. NUERAL PLATE forms i.e., a thickening of ECTODERM caused by changes in cell shape
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3. NEURAL FOLDS and NEURAL GROOVE form -changes in cell shape cause uplifting of cells Neural groove Fig. 47.12 (7 th : 47.14)
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4. NEURAL TUBE forms once neural folds meet - a change in cell adhesion pinches off neural tube from underlying & overlying cells -eventually becomes the SPINAL CORD/BRAIN Neural groove Fig. 47.12 (7 th : 47.14)
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Cells change shape ex: neural tube formation Extension of microtubules helps elongate cells. Contraction of microfilaments causes cells to become wedge shaped. Neural tube forms Fig. 47.17 (7 th : 47.19)
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5. Paired SOMITES of mesodermal tissue flank neural tube: Somites = paired blocks of MESODERMAL cells extending serially along neural tube - form vertebrae, ribs, muscle - mesoderm extensions split (body cavity) Neural groove Fig. 47.12 (7 th : 47.14)
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6. NEURAL CREST CELLS are EPIDERMAL cells above the neural tube - these MIGRATE to form other cell types: e.g., peripheral nerves, pigment cells, teeth, skull bones Neural groove Fig. 47.12 (7 th : 47.14)
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Neural groove (= ectoderm origin) START HERE (= spinal cord) SUMMARY: THE COMPONENTS OF NEURULATION
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th : 47.10, 47.13 and 47.15) Blastoderm (recall: no “blastula” as such) 3 germ layers establshed by gastrulation NEURULATION: Blastoderm edges pinch inward and form a 3-layered “tube”on top of the yolk, then neurulation proceeds above the notocord (plate, folds, tube, etc.) Early embryonic stages in a chick embryo
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micrographs of a chick embryo during neurulation. Neural fold
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Slide Set III SPR11 - SLIDE SET IV OUTLINE Animal...

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