Brain Awareness Week 2012

Welcome to Brain Development

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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 neural development.

Here is Human Development

Here is how the human nervous system grows

Week 3	Week 4 to 5	Week 5	Week 8	Week 13 to 21	Adult Human
Neural Plate	Neural Tube	Simple Tube	Central Nervous	Fetal Brain	Brain Slices

Here is a developing mouse nervous system

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This movie shows a mouse 11.5 days old. (Mouse development takes 21 days and is a model used in research) Red - brain Blue - heart Brown - liver

Mouse E11.5

It begins as a Plate

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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.

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

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

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.

The tube then Closes at each End

Why are these important?

The brain end of the tube forms 3 Vesicles

At the brain end - the tube expands to form three vesicle (sac or bubble) regions. These will form different parts of the brain and brain stem.

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.

Fetal brain Grows

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.

Newborn brain Grows

The brain has not finished growing at birth.

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