Development Of The Nervous System

Question 1

Early development of CNS

Answer 1

Wall of neural tube = neuroepithelium
—> CNS

Slide 4 [pic]

Question 2

Early development of PNS

Answer 2

Neural crest
—> PNS

Slide 4 [pic]

Question 3

Neuroblasts

Answer 3

All neurons with cell bodies in the CNS

Question 4

Glioblasts

Answer 4

Astrocytes, oligodendrocytes

NOTE: anything with -blast tends to be related to development

Question 5

Ependymal cells

Answer 5

Lining ventricles and central canal

Question 6

Differentiation of neuroepithelium

Answer 6

Neuroblasts
Glioblasts
Ependymal cells

Question 7

Differentiation of neural crest cells

Answer 7

Sensory neurons of dorsal root ganglia (cell bodies of sensory neurons)
Postganglionic autonomic neurons
Schwann cells
Non-neuronal derivatives (e.g. melanocytes)

Question 8

Proliferation of neuroepithelium

Answer 8

Slide 8 [pic]

Question 9

Differentiation of neuroepithelium

Answer 9

Slide 9 [pic]

White matter = axons and processes of neurons
Grey matter = nerve cell bodies
Ependymal layer = ventricles

Question 10

Layers of the neural tube

Answer 10

Slide 10 [pic]

NOTE: brain = grey matter on the outside, white matter on the inside. Spinal cord = grey matter on the inside, white matter on the outside

Question 11

What controls differentiation?

Answer 11

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

Question 12

Developing spinal cord

Answer 12

Slide 13 [pic]

Ventral = motor neurons
Dorsal root gnaglion cells —> interneurons
Pathways depend on different sensoryelements

Question 13

Mature spinal cord

Answer 13

Slide 14 [pic]

Question 14

Developing brainstem

Answer 14

Motor nuclei are medial in the brainstem (basal plate)
Sensory nuclei are generally more lateral (alar plate)

Slide 16 [pic]

Question 15

Developing brain

Answer 15

Slide 18-23 [pic]

APPROX 4 WEEK
Future forebrain = prosencephalon
Future midbrain = mesencephalon
Future hindbrain = rhombencephalon
Cephalic flexure
Pontine flexure (level of pons)
Cervical flexure (flex and produces spinal cord below it)

APPROX 5 WEEK
Prosencephalon —> telencephalon + diencephalon (thalamus + hypothalamus)
Rhombencephalon —> pons + medulla

APPROX 8 WEEK
Ventricular system arrives
Developing hemispheres of the brain
Lateral ventricles drain into midline third ventricle
Aqueduct in brainstem drains into fourth ventricle in hind brain (sits behind cerebellum)

TERM
Myelination
Sets up pathways
Allows us to stand up (usually takes 9 months-a year)

Question 16

Developing cortex

Answer 16

Slide 24 [pic]

Folding
Telencephalon:
Radial glial cells provide a scaffolding
Ventricle —> 
Neurons start migrating up 
6 discrete layers of cells make up the cortex

Question 17

Normal development depends on

Answer 17

The coordinated completion of several complex processes (e.g. proliferation, differentiation, migration, axon growth and synapse formation)

NOTE: genetic mutation and environmental factors such as the mother’s lifestyle, diet and teratogens can interfere with these processes. Most of the time, developmental disorders occur during the third trimester

Question 18

Neural tube defects

Answer 18

Slide 27 [pic]

Very rare
Deficit of neural tubes

Question 19

Neural stem cells

Answer 19

Not enough of them

Neural stem cells found in the hippocampus