Presentation on theme: "Principles of Biology, 21 April 2009"— Presentation transcript:
1Principles 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.
2Development Mechanisms of cellular differentiation Fertilization CleavageBlastulationGastrulationNeurulationDirect development and indirect development
3Mechanisms of cellular differentiation Cytoplasmic localizationGradients of molecules within cells determine developmental fate of daughter cells.InductionAdjacent cells determine the developmental fate of a cell.
4Fertilization and activation Prevention of polyspermyFast blockChange in membrane potential.Slow blockCortical reaction causes vitelline membrane to separate from cell membrane.
5The Zygote Gray crescent Polarity Yolk Shows orientation of embryo within zygotePolarityAnimal and vegetal polesYolkProvides nutrition for developing embryo
6Patterns of cleavage Superficial cleavage Ecdysozoan protostomes(nematodes, arthropods, etc)Radial cleavage—primitive deuterostomesDiscoidal meroblastic cleavageReptiles, birds, most fishesRotational holoblastic cleavage—mammalsMosaic vs regulative cleavage