Development of the Nervous System

Question 1

Where does the entire NS originate from?

Answer 1

the neural plate

Question 2

How does the neural tube form?

Answer 2

• 3rd week: neural plate forms neural folds

- these unite to create the neural canal and neural tube

Question 3

Neurulation

Answer 3

Process of the formation of the neural tube

Question 4

What does the neuroepithelium (neural tube wall) differentiate into?

Answer 4

CNS

• Neuroblasts (all neurones with cell bodies in the CNS)
• Glioblasts (astrocytes, oligodendrocytes)
• Ependymal cells (line the ventricles and the central canal)

Question 5

What do neural crest cells differentiate into?

Answer 5

PNS

• sensory neurones of dorsal root ganglia
• Schwann cells
• postganglionic autonomic neurones
• non-neuronal derivatives (e.g. melanocytes)

Question 6

What controls the differentiation?

Answer 6

• Signalling molecules, secreted by surrounding tissues, interact with receptors on neuroblasts
• Control migration & axonal growth by attraction and repulsion
• Depends on concentration gradient & timing

Question 7

What are the layers of the neural tube?

Answer 7

From inside outwards:

• Germinal layer (ependymal layer)
• mantle layer (grey matter)
• marginal layer (white matter)

Question 8

How does the spinal cord develop?

Answer 8

Ventral plate (=basal plate) is where you will find Motor neurones and interneurones. (‘anterior’)

Dorsal plate (=alar plate) is where you will find interneurones. (‘posterior’)

Neural crest cells form sensory neurones in dorsal root ganglia.

Question 9

How does the brainstem develop?

Answer 9

Motor neurones are more medial

sensory neurones are more lateral

Question 10

What does the brainstem consist of?

Answer 10

Midbrain
Pons
Medulla

Question 11

How does the brain develop?

Answer 11

• late 4th week: rostral part of the neural tube undergoes flexion at the level of the mesencephalon
• the alar plate expands on each side forming the telencephalon => cerebral hemispheres

Question 12

what develops into fore, mid and hindbrain?

Answer 12

Prosencephalon -> forebrain
Mesencephalon -> midbrain
Rhombencephalon -> hindbrain

caudal to that is the spinal cord.

Question 13

What does normal development depend on?

Answer 13

Coordinated completion of several complex processes

• proliferation
• differentiation
• migration
• axon growth
• synapse formation

Question 14

What can hinder normal development?

Answer 14

Genetic mutation and environmental factors such as the mother’s lifestyle, diet and teratogens can interfere with these processes

Question 15

Neural tube defects

Answer 15

-> see powerpoint

Question 16

What is the role of radial glial cells?

Answer 16

• important for developing cortex
• vertically oriented
• provide scaffolding for migrating neurones (from ventricle to pial surface)