1. Human Brain Development
*Neural Tube Formation
*Brain Growth
*Synapse Formation
By Cheryl Wilson, Belmont High School

2. Neural Tube Formation- 2. Brain Formation-
induction, proliferation & shape changes
2. Brain Formation-
Proliferation, differentiation & migration
Life Sciences-HHMI Outreach. Copyright 2009 President and Fellows of Harvard College.

3. 3. Wiring the Brain & Nervous System
Each neuron, once in place, must send axon connections to exactly the correct target!
Gray matter-neuronal cell bodies (brownish when fixed)
White matter-neuronal axon (connections)
Some neurons have axons 3 feet long!!!
Finding the proper target to make a connection with is a highly complex process!
Life Sciences-HHMI Outreach. Copyright 2009 President and Fellows of Harvard College.

4. Growth, differentiation, development and normal functioning of the nervous system (like all organ systems) requires: Correct Gene Expression at the Correct Time and Place.

5. Neural Tube Formation in the Human Embryo-Cross Section
Skin
Body Cavity
Neural Tube
Neural Crest
Central Canal
Ectoderm
Mesoderm
Endoderm
Neural Plate
Neural Fold
Notochord & Somites
Neural Groove
Neural Crest
Neural Tube
Early Neural Crest
Neural Tube
Life Sciences-HHMI Outreach. Copyright 2009 President and Fellows of Harvard College.

6. Longitutinal Cross Section of Early Embryo
Cephalic End
Neural Tube (neurons and glia)
Central Canal (will be spinal canal and ventricles)
Caudal End
Life Sciences-HHMI Outreach. Copyright 2009 President and Fellows of Harvard College.

7. The 3-Vesicle Stage of Embryonic Brain Development
and edited by CW
Life Sciences-HHMI Outreach. Copyright 2009 President and Fellows of Harvard College.

8. The 5-Vesicle Stage of Embryonic Brain Development
Metencephalon
Mylencephalon
and edited by CW
Life Sciences-HHMI Outreach. Copyright 2009 President and Fellows of Harvard College.

9. Overview of Brain Development
1. Neural Tube Formation
2. Brain Formation
3. Wiring the Brain & Nervous System
and edited by CW
Life Sciences-HHMI Outreach. Copyright 2009 President and Fellows of Harvard College.
Life Sciences-HHMI Outreach. Copyright 2009 President and Fellows of Harvard College.

10. Longitutinal Cross Section of Early Embryo
Cut
Cephalic End
Neural Tube Cross-Section
Neural Tube (neurons and glia)
Central Canal (will be spinal canal and ventricles)
Caudal End
Life Sciences-HHMI Outreach. Copyright 2009 President and Fellows of Harvard College.

11. Inside Out Brain Growth in the Human Embryo-
Neurons proliferate on the ventricular side of the neural tube Neurons migrate towards the marginal side in waves Each wave of neurons travel past the earlier layers
Again.
Neural Tube (early CNS)
Central Canal (early spinal cord or brain ventricles)
Ventricular zone (inner)
Most neurons migrate radially from the ventricular zone towards the marginal zone, following glial cell fibers.
Again.
Marginal zone (outer)
The next wave of migrating neurons goes past the previously-settled cells.
Again.
Life Sciences-HHMI Outreach. Copyright 2009 President and Fellows of Harvard College.

12. Correct temporal-spatial gene expression is critical for the correct neurons to find each other!
3. Once neurons have reached their final destination, they must now send out their axons to make connections with the correct target and be responsive to receive the correct signals.
2. Cells migrate past the last wave of cells to deposit
1. Ventricular zone-
Where proliferation/cell division occurs
With labelling by CW
Life Sciences-HHMI Outreach. Copyright 2009 President and Fellows of Harvard College.

13.
Life Sciences-HHMI Outreach. Copyright 2009 President and Fellows of Harvard College.