BSC2011_Slide Set 4

BSC2011_Slide Set 4 - 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: _neurulation_ and the development of the _CNS_ 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. _neural plate_ forms i.e., a thickening of ECTODERM caused by changes in _cell shape_
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3. NEURAL fold_ 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 chord and 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 _vertebrates, ribs and muscle__ - mesoderm extensions split (body cavity) Neural groove Fig. 47.12 (7 th : 47.14)
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pairs of mesodermal somites along each side of the neural tube
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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) Early embryonic stages in a chick embryo 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.)
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micrographs of a chick embryo during neurulation. Neural fold
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This note was uploaded on 04/01/2012 for the course BSC BSC2011 taught by Professor Spears during the Spring '10 term at FSU.

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BSC2011_Slide Set 4 - SLIDE SET IV OUTLINE Animal...

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