Outline

3.1 The Same Gene May Play a Role in Many Different Developmental Events

3.2 The Developing Brain Generates Neurons at a Tremendous Rate

3.3 Shortly after Division, Neural Cells Diverge to Become Neurons or Glia

• RESEARCHERS AT WORK Labeling of Dividing Cells Disputes the Idea That Lineage Determines Fate

3.4 The Cerebellum and Cerebral Cortex Form in Layers

3.5 We Can Label Newly Synthesized DNA to Determine the Birthdates of Cells

3.6 Newborn Cells Shinny Up Glial Poles

• RESEARCHERS AT WORK The Cortex Develops in an Inside-Out Manner

3.7 A Few Brain Regions Display Continuing Neurogenesis throughout Life

• BOX 3.1 THE CONTROVERSY OF NEUROGENESIS IN ADULTHOOD

3.8 Neural Crest Cells Migrate to Positions throughout the Body

3.9 Cell Adhesion Molecules Attract and Repel Migrating Cells

3.10 Cerebellar Granule Cells Parachute Down from Above

• RESEARCHERS AT WORK Weaver Neurons Fail to Grasp Glial Fibers

3.11 Cells Crucial for Smell and Reproduction Migrate into the Embryonic Brain