Development of the Nervous System

Question 1

During gastrulation what gives rise to nervous system

Answer 1

Ectoderm

Question 2

What is the name given to the proliferation of the ectoderm in the dorsal midline?

Answer 2

Neural plate- notochord releases factors causing differentiation of these cells into neural ones, differentiating it from skin

Question 3

What happens to the neural plate as it thickens?

Answer 3

It folds up the sides and eventually the two neural folds fuse to form a tube The space in the middle is the neural canal

Question 4

What is the name given to the bunch of cells at the tip of the neural fold that are excluded in the fusion?

Answer 4

Neural crest

Question 5

Which cells do the neural tube and neural crest cells give rise to?

Answer 5

Neural tube – all cells of the CNS Neural crest – all cells of the PNS

Question 6

What is the name given to the wall of the neural tube?

Answer 6

Neuroepithelium

Question 7

What three types of cells do neuroepithelium give rise to?

Answer 7

Neuroblasts – all cells with cell bodies in the CNS Glioblasts – these become neuroglia (astrocytes + oligodendrocytes) Ependymal cells – line the ventricles and the central canal

Question 8

Are motor neurons produced from neuroepithelium?

Answer 8

Yes – although most of their axons are outside the CNS, their cell bodies are within the spinal cord

Question 9

State four cell types that neural crest cells can differentiate into.

Answer 9

Sensory neurons of dorsal root ganglia and cranial ganglia Autonomic post-ganglionic neurons Schwann cells Melanocytes

Question 10

What are the three layers formed by the differentiation of the neuroepithelium?

Answer 10

Ependymal, grey matter and white matter AKA germinal layer, mantle layer, marginal layer

Question 11

Glioblasts show a similar pattern of differentiation to neuroblasts. State one difference.

Answer 11

Glioblasts can migrate into the white matter NOTE: glioblasts do not develop axons (but they do develop processes)

Question 12

What guides the process of differentiation and migration?

Answer 12

Signalling molecules

Question 13

Which factors are important with regards to signalling molecules?

Answer 13

Concentration and timing

Question 14

What can the grey matter of the neural tube be divided into in spinal chord development?

Answer 14

Alar plates dorsally and basal plates ventrally

Question 15

Which types of neurons do the alar plate and basal plate give rise to?

Answer 15

Alar plate – interneurons Basal plate – interneurons and motor neurons

Question 16

Around 4 weeks, you get differentiation of the wall of the anterior neural tube to form three primary vesicles. Name these primary vesicles.

Answer 16

Prosencephalon Mesencephalon Rhombencephalon

Question 17

Describe the changes that occur to these three vesicles in the week or so following their formation.

Answer 17

The first and third vesicles divide in two Prosencephalon -telencephalon + diencephalon Rhombencephalon - pons + medulla

Question 18

What important structure begins to appear quite late in development (around 8 weeks) and where does it appear from?

Answer 18

Cerebellum – appears as an out pouching from the back of the pons

Question 19

Describe the arrangement of motor, sensory and autonomic cranial nuclei within the brainstem.

Answer 19

Motor = medial Sensory = lateral Autonomic = in between

Question 20

What structure divides the motor nuclei from the sensory nuclei in the brainstem?

Answer 20

Sulcus limitans

Question 21

How do neuroblasts migrate from the inner membrane to the outer membrane in the brain?

Answer 21

They attach themselves to radial glial cells and climb up them towards the outer membrane Radial glial cells have their cell bodies anchored to the inner membrane and have a single long process to the outer membrane from the ventricles

Question 22

What happens to neuroblasts that stay in the middle of the cortex?

Answer 22

They become the basal ganglia

Question 23

How many layers of cells are there within the cerebral cortex?

Answer 23

SIX

Question 24

What can a deficiency of folic acid in pregnancy lead to?

Answer 24

Spina bifida

Question 25

What will prosencephalon become

Answer 25

Forebrain

Question 26

What will mesencephalon become

Answer 26

Midbrain

Question 27

What will rhombencephalon become

Answer 27

Hindbrain

Question 28

What does prosencephalon divide into

Answer 28

Telenchephalon and diencepahlon

Question 29

Rhombencephalon divide into

Answer 29

Pons Medulla and later cerebellum which comes out of pons

Question 30

3 layers to neural tube

Answer 30

Inside tube -> germinal layer->mantle layer->marginal layer

Question 31

Migration of neuroblasts in neural tube development

Answer 31

Migrate into mantle layer forming grey matter and their axons project to white layer

Question 32

What forms sensory neurones of spinal chord and dorsal root ganglion

Answer 32

Neural crest

Question 33

What makes up rhomboencephalon in fully developed brain

Answer 33

Metencephalon and myelencephalon

Question 34

Metencephalon

Answer 34

Pons and cerebellum

Question 35

Myelencephalon

Answer 35

Medulla

Question 36

Telencephalon

Answer 36

Cerebral cortex

Question 37

Diencephalon

Answer 37

Thalamus and hypothalamus

Question 38

What ventricles are in prosencephalon

Answer 38

Lateral

Third ventricle

Question 39

Ventricles in mesencephalon

Answer 39

Aqueduct

Question 40

Ventricles in rhomboencephalon

Question 41

What is craniorachischisis

Answer 41

Failed closure of whole length of neural tube

Question 42

What is anencephaly

Answer 42

Failed closure of rostral neural tube

Question 43

Describe development of brainstem

Answer 43

Roof of neural tube proliferates laterally enlarging neural tube to from 4th ventricle. This pushes alar neurones laterally and basal plate medial