Brain Awareness Week 2012

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Welcome to Brain Development

width=320px|height=260px|controller=false|autoplay=true</qt> In today's demonstration we will be looking at how the brain develops from a simple tube into the complex folded structure that you will be seeing (and using) today.


This animation shows a real human adult brain being "sliced", the cortex (grey matter) is on the outside.


This page has been prepared as a simplified introduction to human neural development.

The second part of the demonstration will cover comparative anatomy of the brain.


What is BAW?

Here is Human Development

Human development timeline graph 02.jpg

This graph shows how we divide human development into different times. Key events occur in the first trimester (embryonic), though the neural system continues to develop through the second and third trimester (fetal) and even after birth (postnatal). This is why it one reason why it is so susceptible to damage.

Week 3 - It begins as a Plate

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Quicktime


This embryo is the whole human embryo at just 3 weeks after fertilisation.

  • the entire nervous system will form from the flat region shown in blue.
    • this is called the NEURAL PLATE.


  • the broad blue region at the top will form the brain.



  • the narrow blue region at the bottom will form the spinal cord.
Stage8 SEM1.jpg

This human embryo in week 3 is about 1-1.5 mm long and is viewed from the back, head end to the top. Almost all you see is the neural plate.

Week 4 - That folds to a Tube

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The human embryo is now 4 weeks old and sits on top of a big yolk sac.

  • the neural plate is shown on the embryo back.
  • the plate now folds to form a hollow NEURAL TUBE
Stage10 sem6.jpg

The same view at week 4, the embryo is now 2 - 3.5 mm long. The neural plate can be seen folding down the middle of the back, beginning to form the neural tube.

The tube then Closes at each End

These images show the neural tube closing leaving an opening (neuropore) at each end.

Stage10 sem10.jpg Folatefruit.jpg
Why are these important?


Stage11 sem13c.jpg Stage12 sem1.jpg

Stage15 embryo and brain 01.jpg Stage11 sem100.jpg

Week 6 to 8 - The brain end of the tube forms 3 Vesicles

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Human embryo tomography Carnegie stage 17.jpg

Week 6 - the brain and spinal cord of the human embryo.

Also visible are the heart (bright white) and placental cord containing placental blood vessels.

Week 6 Carnegie stage 17

Stage16 embryo and brain 01.jpg Stage22 embryo and brain 01.jpg

Brain

At the brain end - the tube expands to form three vesicles (sac or bubble) these are described as foe, mid and hindbrain. Each will form different parts of the brain and brain stem as shown below. Many of these you will not have heard of before except for the Cerebrum also called the Cortex.
  1. Forebrain or Prosencephalon - Telencephalon (Amygdala, Hippocampus, Cerebrum or Cortex, Basal Ganglia) and Diencephalon (Epithalamus, Thalamus, Hypothalamus, Subthalamus, Pituitary, Pineal)
  2. Midbrain or Mesencephalon - Tectum
  3. Hindbrain or Rhombencephalon - Cerebellum, Brainstem (Pons, Medulla)
CNS primary vesicles.jpg
Stage 22 image 217.jpg Week 8 the wall of the neural tube at the brain end.

The smaller images (top right) show the section level from the embryo. The thin layer outer called cortical plate will eventually form the adult brain cortex. The other underlying layers are part of the development process and will continue to supply cells to the cortex through fetal period, these layers will eventually be mainly lost. The ventricle is the fluid-filled space within the brain.

Spinal Cord

At the spinal cord end - the tube stays narrow. This region begins to put out motor nerves to innervate muscle and sensory nerves grow towards the developing spinal cord.

Stage22 vertebra and spinal cord 1.jpg Week 8 wall of the neural tube at the spinal cord end, lying behind the vertebral body. The dark central region is where the neurons (cell bodies, grey matter) are located, the pale outer region is where nerve fibres run (axons, white matter). The dorsal root ganglia lie outside the spinal cord and contain the cell bodies of the sensory neurons.

Week 13 onward - Fetal brain Grows

Brain ventricles and ganglia development 03.jpg

This shows the growth of the brain and the fluid-filled space within the brain (the red bar is 1 cm).
  • The brain goes from having a smooth surface to begin to fold or "wrinkle" as the surface area grows.
  • The fluid space is filled with cerebrospinal fluid or CSF.

Dev anat 01.jpg

Salt shaker.jpg

Why do we need this?

Week 40 on - Newborn brain Grows

Motor Development Milestones

The brain has not finished growing at birth.

Growth you can see!

Much of the growth in size after birth is due to "white matter" development, the support cells of the brain, spinal cord and nerves.

The skeleton containers of the nervous system, the skull (brain) and vertebral arch (spinal cord), are still flexible and can expand as the nervous system grows in size.


There is also growth you cannot see!

At the level of cells (neurons), the brain and spinal cord are continuing to make and break connections as the nervous system is remodelled with learning.

Here is how the human nervous system grows

Neuralplate 001 icon.jpg Neuraltube 001 icon.jpg Stage13-CNS-icon.jpg Human embryo tomography Carnegie stage 17.jpg Stage22-CNS-icon.jpg Brain fissure development 03.jpg Adult human brain movie icon.jpg
Week 3 Week 4 to 5 Week 5 Week 6 Week 8 Week 13 to 21 Adult Human
Neural Plate Neural Tube Simple Tube Folded Tube Central Nervous Fetal Brain Brain Slices

Here is a developing mouse nervous system

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This movie shows a 11.5 days old mouse brain.

(Mouse development takes 21 days and is a model used in research)


Red - brain



Blue - heart



Brown - liver


Mouse CT E11.5 movie-icon.jpg

Mouse E11.5

Comparative Brain Anatomy

Frog and Dog Brain

In today's demonstration you will also see some models of brains from different species. Each coloured part on the brain models shows a different brain region each with a different function. Each brain region is the same colour (code) in all models.

  1. Do not worry about the names of all the different structures.
  2. Can you see the same coloured structures in all the brains?
  3. Are the same coloured structures the same shape and size in all brains?


(Link to Detailed Information, not part of demonstration)

About Brain Awareness Week

BAW icon 2012.jpg BAW - Brain Awareness Week is an inspirational global campaign that unites those who share an interest in elevating public awareness about the progress and benefits of brain and nervous system research.



More? Society for Neuroscience


More K12 Development Topics

K12 Links: Start Here | Week 1 | Week 2 | Week 3 | Week 4 | Week 5 to 8 | Arms and Legs | Heart | Fetus | Brain Growth | Eyes and Ears | Animal Development Times | Humans and Animal Embryology | Comparative Embryology | Thalidomide



Glossary Links

Glossary: A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | Numbers | Symbols | Term Link

Cite this page: Hill, M.A. (2024, March 28) Embryology Brain Awareness Week 2012. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Brain_Awareness_Week_2012

What Links Here?
© Dr Mark Hill 2024, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G