BIOL302 Study Guide - Regional Differentiation, Primitive Streak, Marginal Zone
18 May 2013
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Both = set of morphological movements that leads to formation of 3 germ layers. Birds: blastodisc has large yolk underlying i = prevent formation of cells along yolk. First cells through streak = endoderm, second cells = mesoderm. Amphibians: begin gastrulationn below grey crescent with invagination to form blastopore lip. 2: compare and contrast formation of nieuwkoop center in amphibians and birds. Explain your reasoning (in respect to their role in gastrulation). You can use diagrams: amphibian (xenopus) nieuwkoop centre, cytoplasmic rotation following fertilization. B-catenin in dorsal and protein vg1 secreted by vegetal cells. Node is equivalent to dorsal blastopore lip (spemann"s organizer) Blastocyst = mammalian blastula, formed when inner cell mass is positioned on one side as the blastocoel expands: embryo formed at end of mammal cleavage, created through secretion of na+ by trophoblast in morula. Zona pellucida role during fertilization keeps embryo from implanting on oviduct.
