Presentation on theme: "Principles of Biology, 21 April 2009"— Presentation transcript:
1 Principles of Biology, 21 April 2009 Animal developmentPrinciples of Biology, 21 April 2009Donald WinslowReferences:Hickman, Cleveland P.; et al Integrated Principles of Zoology, 14th ed., McGraw-Hill, NY., Chapter 8.Mader, Sylvia S Biology, 9th ed., McGraw-Hill, NY., Chapter 44.
2 Development Mechanisms of cellular differentiation Fertilization CleavageBlastulationGastrulationNeurulationDirect development and indirect development
3 Mechanisms of cellular differentiation Cytoplasmic localizationGradients of molecules within cells determine developmental fate of daughter cells.InductionAdjacent cells determine the developmental fate of a cell.
4 Fertilization and activation Prevention of polyspermyFast blockChange in membrane potential.Slow blockCortical reaction causes vitelline membrane to separate from cell membrane.
5 The Zygote Gray crescent Polarity Yolk Shows orientation of embryo within zygotePolarityAnimal and vegetal polesYolkProvides nutrition for developing embryo
6 Patterns of cleavage Superficial cleavage Ecdysozoan protostomes(nematodes, arthropods, etc)Radial cleavage—primitive deuterostomesDiscoidal meroblastic cleavageReptiles, birds, most fishesRotational holoblastic cleavage—mammalsMosaic vs regulative cleavage