Development of brain and spinal cord

Question 1

Development of brain and spinal cord- weekly progress

Answer 1

w3- neural tube formation
w10- basic brain region formation begins
w13- neuronal migration begins
w15- structural formation begins
w25- synaptic pruning begins
w28> w40- myelination begins- brain growth spurt

Question 2

What are the 3 primary brain vesicles

Answer 2

Prosencephalon (forebrain)
Mesencephalon (midbrain)
Rhomboencephalon (hindbrain)
3-4 week embryo

Question 3

What are the 5 secondary brain vesicles?

Answer 3

Telencephalon ( from P)
Diencephalon ( from P)
Mesencephalon (from M)
Metencephalon ( from R)
Myelencephalon (from R)

Question 4

What are the adult brain structures?

Answer 4

Cerebrum- cerebral hemispheres (cortex, white mater, basal nuclei) (from T)
Diencephalon- thalamus, hypothalamus, epithalamus, retina- (from D)
Brain stem- midbrain (from Mes)
Brain stem- pons (from met)
Cerebellum (from met)
Brainstem- medulla oblongata (from myele)

Question 5

What happens to neural tubes by 4th week?

Answer 5

Bend to form

• Midbrain flexure between prosencephalon/mesencephalon
• Cervical flecure between hindbrain and spinal cord
• Pontine flexure in hindbrain

Question 6

Development of the ventricles

Answer 6

• Derived from dilation of neural canal of neural tube- dilations within prosencephalon lead to formation of lateral ventricles and 3rd ventricle
• Cavitation of mesencephalon forms cerebral aqueduct

Question 7

Development of brain and spinal cord

Answer 7

Ependymal (neuroblast layer)- stem cells for all neurons: divide and give rise to

• Mantle (intermediate) layer- cell bodies of motor neuron (gray matter)
• Marginal layer- contains axons of motor neurons (white matter)

Question 8

What are the regions of the mantle layer

Answer 8

Mantle layer divided into
Roof plate- posterior median septum
Alar plate- dorsal (sensory) receives sensory axons from DRG
Basilar plate- ventral (motor)- contains cell bodies of motor neurons
Floor plate- ventral medial fissure
Neuroepithelium gives rise to neuroblasts (neurons), glioblasts (astrocytes/oligodendrocytes)

Question 9

Neurogenesis- proliferation

Answer 9

Process by which neurons and glia proliferate, migrate+ specified to form mature brain
Neuroepithelial cells line wall of neural tube (neuro/glioblasts)

Question 10

Neurogenesis- migration

Answer 10

Cell layering occurs as NB migrate toward periphery following set patterns
Glial mediated migration relies on radial glial cells
Somal translocation self directed

Question 11

Neurogenesis- synaptogenesis

Answer 11

After elongation axons and dendrites make contacts and establish initial synpases
Synapses continuously reconfigured in development and throughout life (syn. plasticity) forms the basis for learning and memory

Question 12

What is synaptic pruning?

Answer 12

Synaptic pruning is targeted elimination of functional synapses
Synaptic density in cerebral cortex changes with age- peaks age 1/2, drops in adolescence and stablises in adulthood