Talk:K12 Brain Awareness Week

From Embryology


The Evolving Brain Video - The Evolving Brain

Cerebrum Comparative Anatomy

  • All brains have a similar mechanism of early development, neural plate, tube, etc.
  • All brains will have similar regions with similar functions.
  • Each animal brain though will end up a different size, shape and complexity (overall and of regions).
  • The information shown below is a detailed comparison of different species cerebrum development.

This Information is beyond K12 level and not part of today's demonstration.

Back to - BAW Comparative Anatomy

Primitive vertebrates

Lamprey cartoon.jpg


  • (hagfishes and lampreys)
  • cerebrum is a relatively simple structure receiving nerve impulses from the olfactory bulb.

Some fish and amphibians

(Cartilaginous fish (sharks), lobe-finned fish, amphibians)

  • remains mainly devoted to olfactory sensation.
  • Cerebrum divided into 3 regions.
  1. ventral - forms the basal nuclei, and contains fibres connecting the rest of the cerebrum to the thalamus.
  2. lateral - forms the paleopallium.
  3. dorsal - forms the archipallium.

Ray-finned Fish



  • Cerebrum lateral and ventral regions inner surfaces bulge up into the ventricles.
    • these include both the basal nuclei and the various parts of the pallium (complex in structure in teleosts).
  • Verebrum dorsal surface is membranous, and does not contain any nervous tissue.

In amniotes, the cerebrum becomes increasingly large and complex.


Rana pipiens.jpg


  • paleopallium is larger than in amphibians, and its growth has pushed the basal nuclei into the central regions of the cerebrum.
  • Grey matter is generally located beneath the white matter
    • in some reptiles, grey matter spreads out to the surface to form a primitive cortex (anterior part of the brain).


Chick E12.jpg

Chicken E12

  • enlarged compared to reptiles, due to the basal ganglia.
    • other areas remain primitive in structure.
    • no expansion of the cerebral cortex
  • above basal ganglia the HVC develops
    • involved with learning complex tasks, such as song.




  • cortex covers almost the whole of the cerebral hemispheres (greatest in primates).
    • paleopallium is pushed to the ventral surface of the brain, where it becomes the olfactory lobes
    • archipallium becomes rolled over at the medial dorsal edge to form the hippocampus.
    • corpus callosum connects the two hemispheres.
  • surface folding found only in higher mammals.

Back to - BAW Comparative Anatomy

Neural Tube Development

Neural Tube Development
Neural Tube Primary Vesicles Secondary Vesicles Adult Structures
week 3 week 4 week 5 adult
neural plate
neural groove
neural tube

prosencephalon (forebrain) telencephalon Rhinencephalon, Amygdala, hippocampus, cerebrum (cortex), hypothalamus‎, pituitary | Basal Ganglia, lateral ventricles
diencephalon epithalamus, thalamus, Subthalamus, pineal, posterior commissure, pretectum, third ventricle
mesencephalon (midbrain) mesencephalon tectum, Cerebral peduncle, cerebral aqueduct, pons
rhombencephalon (hindbrain) metencephalon cerebellum
myelencephalon medulla oblongata, isthmus
spinal cord, pyramidal decussation, central canal

Old Movie Links

These have been replaced on page.

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


  • Cerebral cortex - (grey matter, cortex) Embryonic structure that will form the cerebral cortex of the brain. Formed in sequence from neural tube, prosencephalon (primary vesicle), telencephalon (secondary vesicle) then cerebrum or cortex.
  • Cerebellum - (Latin, cerebellum = little brain) Formed from the rhombencephalon (hindbrain), it is required for coordinated motor activities.
  • Diencephalon - At the level of the diencephalon that the optic stalks (optic nerve) extends from the brain. The diencephalon lumen (cavity of the neural tube) will form the third ventricles.
  • Encephalon - brain.
  • Medulla - (medulla oblongata) A brain stem region within the central nervous system, this is the last part of the brain before becoming the spinal cord. It lies beneath the medulla.
  • Midbrain - The embryonic neural tube region that will form midbrain structures of the tectum (roof of the midbrain, auditory and visual reflexes) and tegmentum (floor of the midbrain, several brain nuclei) in the adult brain. The mesencephalon is the middle of the 5 secondary brain vesicles formed from the mesencephalon of the primary brain vesicle (there are 3 primary brain vesicles). The mesencephalon lumen (cavity of the neural tube) will form the midbrain aqueduct.
  • Pons - (Latin, pons = "bridge") A brain stem region within the central nervous system, it lies above the medulla.
  • Telencephalon - (endbrain) The embryonic neural tube region that will form cerebral hemispheres (neocortex, basal nuclei, palaeocortex, archicortex). The telencephalon is the most anterior of the 5 secondary brain vesicles formed from division of the prosencephalon (forebrain) primary brain vesicle (there are 3 primary brain vesicles). The telencephalon lumen (cavity of the neural tube) will form the lateral ventricles.