Chapter 8 Outline

Chapter 8: Conceptualizing Early Development: A Summary of the Essential Processes

Early development shapes the tree of life

  • Diploblastic animals: Cnidarians and ctenophores
  • Triploblastic animals: Protostomes and Deuterostomes
  • Common themes of early development

From once cell to many: Cleavage

  • Patterns of cleavage
  • The mid-blastula transition

The “goals” of gastrulation

  • Cell movements during gastrulation
  • The evolutionary origins of gastrulation

Achieving the “goals”: Canonical events that power gastrulation

  • Step 1: Initiate the site of internalization
  • Step 2: Move cells inside
  • Step 3: Axis elongation

The “aim” of axis determination

  • Organizing the embryo: A historic transformation
  • A common developmental mode for axis formation
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