Transcript What are the phases of prenatal neurodevelopment?

Psychology 304:
Brain and Behaviour
Lecture 19
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The Development of the Nervous System
1. What are the phases of prenatal neurodevelopment?
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By the end of today’s class, you should be able to:
1. discuss the process of prenatal development of the
nervous system and other bodily organs.
2. describe the directions and mechanisms associated with
cell migration.
3. explain how cells differentiate into region-specific
neurons and glial cells.
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What are the phases of prenatal neurodevelopment?
• Prenatal neurodevelopment is marked by a number of
discrete phases:
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1. Development of the neural plate and neurogenesis.
 Shortly after conception, the embryo shows three
cell layers: The ectoderm, mesoderm, and endoderm.
 The nervous system develops from the neural plate,
which is evident 3 weeks after conception.
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Develops into the PNS.
Formation of Neural Tube
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Electron Micrograph of Neural Tube Closure
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Electron Micrograph of Neural Tube Closure
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Neural Tube
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Embryonic Neural Tube Development
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 Once formed, the cells that line the inner surface of
the neural tube—that is, the ventricular zone—divide
and proliferate.
 The anterior end of the neural tube ultimately
develops into the forebrain, midbrain, and hindbrain.
 The posterior end of the neural tube ultimately
develops into spinal cord.
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Forebrain
Midbrain
Hindbrain
Spinal cord
CNS Development from the Neural Tube
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2. Cell migration
 Once cells have developed in the ventricular zone,
they migrate to target locations.
 Migration occurs in two directions: radial migration
and tangential migration.
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Directions of Migration
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 Cells migrate via two mechanisms: somal translocation
and glia-mediated migration.
 Cell migration is guided be cell-adhesion molecules.
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Processes of Migration
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Glial-Mediated Migration
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3. Cell differentiation
 Once cells have reached their target locations, they
differentiate into region-specific neurons and glial
cells.
 Cell differentiation is determined by genetic programs
and cell-cell interactions (i.e., induction).
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The Development of the Nervous System
1. What are the phases of prenatal neurodevelopment?
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