K12 Brain Awareness Week

Embryology - 11 Dec 2023        Expand to Translate
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Welcome to Brain Development

MP4 | Quicktime

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. March 12 – 18 2018 (Sydney Australia) What is BAW? | SfN

Here is Human Development

This graph shows how we divide human development into different times. Key events occur in the first trimester (embryonic). The neural system continues to develop through the second and third trimester (fetal) and even after birth (postnatal). This long complex development makes it more easy to damage.

Week 3 - It begins as a Plate

<html5media height="530" width="320">File:Neuralplate_001.mp4</html5media> Movie

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 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. Early development of brains for vertebrate species develop in exactly the same way.

Week 4 - That folds to a Tube

<html5media height="480" width="480">File:Neuraltube_001.mp4</html5media> Movie

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, 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.

Why are these important?

Week 4 - what the neural tube looks like when cut across.	Week 5 - what the neural tube looks like within the embryo.

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

Brain

At the brain end - the tube expands to form three vesicles (expansions, sacs or bubbles) these are described as fore-, mid- and hind-brain. Each vesicle will form different parts of the brain. Many of these parts you will not have heard of before, except the outer brain surface the Cerebrum or Cortex. Forebrain or Prosencephalon - Telencephalon (Cerebrum or Cortex, Amygdala, Hippocampus, Basal Ganglia) and Diencephalon (Epithalamus, Thalamus, Hypothalamus, Subthalamus, Pituitary, Pineal) Midbrain or Mesencephalon - Tectum Hindbrain or Rhombencephalon - Cerebellum, Brainstem (Pons, Medulla)

<html5media height="600" width="520">File:Human embryo tomography Carnegie stage 17.mp4</html5media> Movie

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

Week 8 - the wall of the neural tube at the brain end. The "white matter" (thin outer layer, cortical plate) will eventually form the adult brain cortex. The other labeled layers are part of the development process and will eventually be mainly lost. The ventricle is the fluid-filled space within the neural tube and also later the brain. The smaller images (top right) show the level from the embryo.

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.

Week 8 wall of the neural tube at the spinal cord end. Spinal cord lies behind the vertebral body. The "grey matter" is on the inside of the spinal cord and the outside of the brain. The "grey matter" (dark central region) is where the neurons (cell bodies) are located, the "white matter" (pale outer region) is where nerve pathways run (axons). The sensory neurons lie outside the spinal cord in the dorsal root ganglia.

Second Trimester - Fetal brain Grows in Size

This Scan of the living brain, shows the growth that occurs during the second trimester (red bar top right is 1 cm). The left and right halves of the brain (hemispheres) can be clearly seen. As the brain grows a large groove (fissure) also appears in the side surface (Sylvian fissure). The fluid space (purple) is filled with cerebrospinal fluid or CSF.

Third Trimester - Fetal brain Grows in Surface Area

The brain goes from a smooth surface to begin to fold or "wrinkle". These folds are due to the millions of cells being pushed into the cortex, increasing the surface area. A groove is called a fissure (plural, fissures). A fold is called a gyrus (plural, gyri).

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!
A Neuron - the functional unit of the nervous system. To small to see with your eyes (you need a microscope) the body cell called a neuron forms the basic unit that makes up the entire nervous system. Neurons form connections with other neurons and they are supported by specialized cells the glial cells. Billions of neurons in the brain make and break connections throughout your entire life, as the nervous system is remodelled with learning.
When things go wrong... When neurons in the brain either function incorrectly or die, you have a neurological disease. Damage to spinal cord neurons and their connections (car accidents, bike accidents, diving, falls, impact, etc) is called a spinal cord injury. Abnormal growth of the support cells causes most of the brain cancers. Damage to the blood supply to the brain is the cause of brain strokes.

Here is how the human nervous system grows

‎‎Neural Plate Page | Play	‎‎Neural Tube Close Page | Play	‎‎Neural Tube Page | Play	‎‎Stage 13 Neural Page | Play	‎‎Stage 17 Embryo Page | Play
Week 3	Week 4	Week 4 to 5	Week 5	Week 6
‎‎Stage 22 Neural Page | Play	‎‎Sylvian Fissure Page | Play
Week 8	Week 13 to 21

Here is a developing mouse nervous system

<html5media height="420" width="340">File:Mouse CT E11.5.mp4</html5media> Movie

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 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.

• Yellow - (forebrain) cortex
• Blue - (midbrain) vision and hearing pathway, motor control, sleep/wake, arousal
• Brown - (hindbrain) cerebellum

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?

Watch the video - The Evolving Brain (5 min)
<html5media height="360" width="480">http://www.youtube.com/watch?v=BUzeEpcO238</html5media> brainfacts.org - The Evolving Brain

(Link to Detailed Information, not part of demonstration)

About Brain Awareness Week

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. This current page is an updated version of earlier presentations in 2012, 2013, 2014, 2015 and 2017.

More? Society for Neuroscience - BAW | www.brainfacts.org

More K12 Development Topics

More development movies

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Glossary Links

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Cite this page: Hill, M.A. (2023, December 11) Embryology K12 Brain Awareness Week. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/K12_Brain_Awareness_Week

What Links Here?

© Dr Mark Hill 2023, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G