Human Brain Development
*Neural Tube Formation
*Brain Growth
*Synapse Formation
By Cheryl Wilson, Belmont High School
http://en.wikipedia.org/wiki/Brain_development
http://commons.wikimedia.org/wiki/File:Brain_090407.jpg
http://commons.wikimedia.org/wiki/File:Neuron_with_mHtt_inclusion.jpg
1. Neural Tube Formation-
2. Brain Formation-
induction, proliferation & shape changes
Proliferation, differentiation & migration
http://commons.wikimedia.org/wiki/File:Gray16.png
http://en.wikipedia.org/wiki/Brain_development
http://en.wikipedia.org/wiki/Brain_development
Life Sciences-HHMI Outreach. Copyright 2009 President and Fellows of Harvard College.
http://commons.wikimedia.org/wiki/File:Fetus.jpg
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!
http://upload.wikimedia.org/wikipedia/commons/b/ba/Nervous_system_diagram.png
http://commons.wikimedia.org/wiki/File:Visible_Human_head_slice.jpg
Life Sciences-HHMI Outreach. Copyright 2009 President and Fellows of Harvard College.
Growth, differentiation, development and normal functioning
of the nervous system (like all organ systems) requires:
Correct Gene Expression at the Correct Time and Place.
http://commons.wikimedia.org/wiki/File:Complete_neuron_cell_diagram_en.svg
Neural Tube Formation in the Human Embryo-Cross Section
Neural Crest
Central Canal
Neural Tube
Ectoderm
Mesoderm
Body Cavity
Endoderm
Skin
Neural Plate
Neural Crest
Neural Tube
Neural Groove
Neural Fold
Notochord & Somites
Early Neural Crest
Neural Tube
Life Sciences-HHMI Outreach. Copyright 2009 President and Fellows of Harvard College.
Longitutinal Cross Section of Early Embryo
Cephalic End
Neural Tube (neurons and glia)
Central Canal (will be
spinal canal and ventricles)
Caudal End
http://en.wikipedia.org/wiki/Brain_development
Life Sciences-HHMI Outreach. Copyright 2009 President and Fellows of Harvard College.
The 3-Vesicle Stage of Embryonic Brain Development
http://commons.wikimedia.org/wiki/File:4_week_embryo_brain.jpg
http://commons.wikimedia.org/wiki/File:Encephalon.png
and edited by CW
Life Sciences-HHMI Outreach. Copyright 2009 President and Fellows of Harvard College.
The 5-Vesicle Stage of Embryonic Brain Development
Metencephalon
Mylencephalon
http://commons.wikimedia.org/wiki/File:6_week_embryo_brain.jpg
and edited by CW
http://commons.wikimedia.org/wiki/File:Encephalon.png
Life Sciences-HHMI Outreach. Copyright 2009 President and Fellows of Harvard College.
Overview of Brain Development
1. Neural Tube Formation
2. Brain Formation
3. Wiring the Brain
& Nervous System
http://upload.wikimedia.org/wikipedia/en/1/1b/Development_of_nervous_system.png
and edited by CW
http://commons.wikimedia.org/wiki/File:4_week_embryo_brain.jpg
http://commons.wikimedia.org/wiki/File:6_week_embryo_brain.jpg
http://commons.wikimedia.org/wiki/File:Brain_bulbar_region.svg
http://en.wikipedia.org/wiki/Brain_development
Life Sciences-HHMI Outreach. Copyright 2009 President and Fellows of Harvard College.
Life Sciences-HHMI Outreach. Copyright 2009 President and Fellows of Harvard College.
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
http://en.wikipedia.org/wiki/Brain_development
Life Sciences-HHMI Outreach. Copyright 2009 President and Fellows of Harvard College.
Inside Out Brain Growth in the Human EmbryoNeurons 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
Neural Tube (early CNS)
Central Canal (early spinal cord or brain ventricles)
Ventricular zone
(inner)
Marginal zone
(outer)
Most neurons migrate
radially from the
ventricular zone towards
the marginal zone,
following glial cell fibers.
The next wave of
migrating neurons goes
past the previously-settled
cells.
Life Sciences-HHMI Outreach. Copyright 2009 President and Fellows of Harvard College.
Again.
Again.
Again.
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 zoneWhere proliferation/cell
division occurs
http://en.wikipedia.org/wiki/Brain_development
With labelling by CW
Life Sciences-HHMI Outreach. Copyright 2009 President and Fellows of Harvard College.
http://commons.wikimedia.org/wiki/File:Gray754.png
Life Sciences-HHMI Outreach. Copyright 2009 President and Fellows of Harvard College.