Embryonic formation

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Embryonic formation

• Chapter 7
• By Porter an Clark

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Fertilization

• During fertilization in organisms, the male
  gamete, sperm fuses with a female gamete, ovum to
  form a zygote.
• Gametes are haploid cells that contain one
  complete set of chromosomes.
• When the gametes fuse the create a zygote- a cell
  that has two complete sets of chromosomes know as
  a diploid.
• The zygote is ready to begin cell division, cell
  movement and cell differentiation, the process in
  which cells specialize

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Blastulation

• Cleavage, early cell divisions of a fertilized
  ovum, forms the blastula, a hollow ball of
  surrounded by hundreds of cells.
• Blastula stage is the earliest stage of embryonic
  development
• Once it has formed individual cells flow from the
  surface to the interior of the blastula so that a
  new layer lines the original blastula.

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Gastrulation

• The result of the cell movement is a blastula
  which has three distinct layers
• A surface layer-ectoderm, a new inner layer
  endoderm, and a layer in between the mesoderm
• All develop to form specialized tissues.
• In all cells there is an identical set of genes.
  As the cells specialize different sets of genes
  are activated in different cells

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Questions

• What are the male and female gametes?
• What cell activities occur after the zygote
  forms?
• What are the three layers of the gastrula?

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