Amphibians and Fish


Fertilization, Cortical Rotation, and Cleavage

  • Unequal radial holoblastic cleavage
  • The mid-blastula transition: Preparing for gastrulation

Amphibian Gastrulation

  • Epiboly of the prospective ectoderm
  • Vegetal rotation and the invagination of the bottle cells
  • Involution at the blastopore lip
  • Convergent extension of the dorsal mesoderm

Progressive Determination of the Amphibian Axes

  • Specification of the germ layers
  • The dorsal-ventral and anterior-posterior axes

The Work of Hans Spemann and Hilde Mangold: Primary Embryonic Induction

Molecular Mechanisms of Amphibian Axis Formation

  • How does the organizer form?
  • Functions of the organizer
  • Induction of neural ectoderm and dorsal mesoderm: BMP inhibitors
  • Conservation of BMP signaling during dorsal-ventral patterning

Regional Specificity of Neural Induction along the Anterior-Posterior Axis

Specifying the Left-Right Axis


Zebrafish Cleavages: Yolking Up the Process

Gastrulation and Formation of the Germ Layers

  • Progression of epiboly 3
  • Internalization of the hypoblast
  • The embryonic shield and the neural keel

Dorsal-Ventral Axis Formation

  • The fish blastopore lip
  • Teasing apart the powers of Nodal and BMP during axis determination

Left-Right Axis Formation