Chapter 8 Chapter Outline

Snails, Flowers, and Nematodes: Different Mechanisms for Similar Patters of Specification

A Reminder of the Evolutionary Context That Built the Strategies Governing Early Development

  • The diploblastic animals: Cnidarians and ctenophores
  • The triploblastic animals: Protostomes and deuterostomes
  • What’s to develop next

EARLY DEVELOPMENT IN SNAILS

Cleavage in Snail Embryos

  • Maternal regulation of snail cleavage
  • Axis determination in the snail embryo

Gastrulation in Snails

THE NEMATODE C. ELEGANS

Cleavage and Axis Formation in C. elegans

  • Rotational cleavage of the egg
  • Anterior-posterior axis formation
  • Dorsal-ventral and right-left axis formation
  • Control of blastomere identity

Gastrulation of 66 Cells in C. elegans

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