bicd130_06_lecture4r - BICD 130 Embryos Genes and...

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Unformatted text preview: BICD 130 Embryos, Genes, and Development BICD 130 Final Section Schedule Section Day Time Room 1 (DL) 2 (DL) 3 (JF) 4 (JF) Tu W F F 5:00p - 5:50p 5:00p - 5:50p 8:00a - 8:50a 9:00a - 9:50a York 3050A Center 218 WLH 2208 WLH 2208 Comparison of the blastula stage in various embryos Gastrulation: process of rearranging the cells of the embryo following cleavage (blastula stage) in order to establish a multi-layered body plan Body organization of a generic animal gastrulation = "gut formation" Three germ layers are established by gastrulation Outer layer: ectoderm -epidermis (skin) -nervous system Inner layer: endoderm -lining of the gut -digestive organs Middle layer: mesoderm -organs -connective tissue -blood It is not birth, marriage, or death, but gastrulation, which is truly the most important time in your life. LEWIS WOLPERT The sea urchin larva (pluteus) blastula Sea urchin fate map Sea urchin lineage Hrstadius: Role of sea urchin micromeres in inducing the fates of other blastomeres The sea urchin larva (pluteus) Sea urchin gastrulation blastopore: first opening in the blastula wall created by gastrulation archenteron: primitive gut primary mesenchyme cells form spicules blastopore secondary mesenchyme cells assist in archenteron extension Archenteron extension in sea urchin gastrulation archenteron convergent extension blastopore Gastrulation creates the body plan of the sea urchin larva Protostomes vs. deuterostomes Protostomes ("mouth first"): blastopore becomes the mouth [molluscs, arthropods (insects), worms] Deuterostomes ("mouth second"): blastopore becomes the anus; mouth forms second [echinoderms, vertebrates] Gastrulation in an insect (protostome) Extension of the germ band during Drosophila gastrulation Gastrulation creates the body plan of the Drosophila larva Gastrulation creates the body plan of the Drosophila larva Anterior midgut invagination Polarization of the amphibian embryo along the A/V axis originates in the egg The major axes of the animal body (caudal) (rostral) The point of sperm entry defines the D/V axis of the frog embryo Fate maps of the Xenopus (frog) blastula Gastrulation begins at the future dorsal side of the Xenopus embryo ...
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