neurogenesis

Question 1

what is the ventricular zone?

Answer 1

band around the lumen of the neural tube

Question 2

what is the early neural tube described as?

Answer 2

1 cell wide neuroepithelium
OR
pseudo-stratified epithelium

Question 3

DEFINE: interkinetic migration

Answer 3

nuclei shuttling up and down the process of the radial glial cell

Question 4

how do neuroepithelial cells divide to give rise to neuronal progenitors?

Answer 4

1. early neuroepithelial cells divide into 2 identical daughter cells
2. daughter cells change shape and become radial glia cells
3. radial glia divide asymmetrically to give rise to 1 identical radial glia daughter and a 2nd daughter that will differentiate into a neuron
4. 2nd daughter migrates away from ventricular zone using scaffold provided by its sister’s process and becomes a neurogenic progenitor

Question 5

Proneural genes

Answer 5

provide the competence to become neural cells

e.g. achaete scute

Question 6

DEFINE: lateral inhibition

Answer 6

a special kind of inhibition that makes initially similar cells become different from one another by the transmission of an inhibitory signal between a pair or cluster of cells to prevent cells receiving the signal from adopting a particular fate

Question 7

Describe the processes underlying the role of notch signalling in neurogenesis

Answer 7

1. initially cell 1 and cell 2 express same levels of achaete-scute, notch and delta
2. a slight imbalance in notch signalling results in cell 2 receiving more delta than cell 1
3. notch signalling pathway is activated in cell 2
4. notch upregulates suppressor of hairless
5. suppressor of hairless upregulates enhancer of split
6. enhancer of split represses achaete-scute
7. achaete-scute maintains delta so in cell 2, delta is not expressed
8. cell 1 no longer receives delta
9. notch signalling normally suppresses achaete scute so in cell 1, achaete scute is expressed at high levels.
   cell 1 becomes a neuronal precursor
   cell 2 remains as a radial glial cell

Question 8

during M phase of mitosis, where are the nuclei located during interkinetic nuclear migration?

Answer 8

near the lumen of the neural tube 
                               OR 
apical surface
                               OR 
ventricular surface

Question 9

Microtubule associated proteins

Answer 9

LIS1

DCX

Question 10

Lissenchephaly

Answer 10

• missing sulci and gyri
• mutation in α-tubulin, β-tubulin, LIS1 and DCX = microtubule function
• mutation in Reelin
• failure of neuronal precursors to migrate along radial glial process

Question 11

where are Cajal-Retzius cells formed?

Answer 11

marginal zone

Question 12

Reeler mouse mutant

Answer 12

mutation in reelin = large ECM protein found in Cajal-Retzius cells
failure of cajal-retizius cells and subplate neurons to seperate + cortical plate forms beneath them

Question 13

where are the two major zones of adult stem cells located in the adult brain?

Answer 13

• subventricular zone

- dentate gyrus of hippocampus

Question 14

where do inhibitory interneurons of the cortex, olfactory bulb and striatum migrate in from?

Answer 14

subpallium

Question 15

the inhibitory interneurons that go into the cortex are…….

Answer 15

GABA-ergic

Question 16

the inhibitory interneurons that go into the striatum are…….

Answer 16

cholinergic

Question 17

what are some methods used to trace neuronal migration?

Answer 17

• lipophilic dyes (to trace cells)
• transplantation experiments between quail and chick
• inject viruses carrying GFP into rodents –> infects ventricular zone
• induce fluorescent protein in just a subset of cells (conditional prelox)

Question 18

where is the cerebellum located?

Answer 18

roof of 4th ventricle above the medulla

Question 19

what do anterior rhombic lip cells give rise to?

Answer 19

granule neuron precursors

Question 20

what do posterior rhombic lip cells give rise to?

Answer 20

pontine nuclei

inferior olive

Question 21

MATH-1

Answer 21

transcription factor expressed in proliferating external germinal layer cells
also expressed in the pons

Question 22

development of the cerebellum

Answer 22

1. external germinal layer cells form on the outside of the neural tube
2. EGCs = highly proliferative. at the same time, EGCs start differentiating into granule cells.
3. differentiating granular neuron cell body migrate tangentially into inner granular layer
4. differentiated granule cells extend their axons (parallel fibres) outwards into the EGL and synapse onto Purkinje cell dendrites
   - purkinje cells located in the purkinje cell layer and they secrete Shh = mitogen for granular neuron precursor

Question 23

DISEASE: pontocerebellar hypoplasia

Answer 23

smaller pons and cerebellum

mutation in MATH-1

Question 24

where does the cerebellum arise from?

Answer 24

anterior rhombic lip cells