Neuronal migration in CNS development

Question 1

2. What is pseudostratified?

Answer 1

Early neuroepithelium

Question 2

3. How thick is the early neuroepithelium?

Answer 2

1 cell thick

Question 3

4. How do the nuclei move?

Answer 3

Up and down

Question 4

5. On what surface does the M phase of cell cycle occur?

Answer 4

Ventricular surface

Question 5

7. How is the division early on in these cells?

Answer 5

Symmetrical

- Early phase expands neuroepithelium

Question 6

8. What is produced when the division becomes asymmetric?

cytoplasmic components allocated differently

Answer 6

Radial glia (stem cell like & spread apical to basal surfaces)
Neuronal precursor

Question 7

9. What do these neuronal precursors do to then become mature neurons?

Answer 7

Migrates out up radial glial fibres to upper areas called the mantal zone and here becomes a mature neuron

Question 8

10. Where do cells ‘born’ later move to?

Answer 8

The top/higher/outside

Question 9

11. What do heterochronic transplant test?

Answer 9

Tests whether the fates of neuronal precursors is plastic or fixed

Question 10

12. What happens if early precursors are transplanted to older host?

Answer 10

Fate is plastic

Question 11

14. What is lissencephaly?

Answer 11

Brain surface smooth due to improper/defective neuronal migration

Question 12

15. What genes are mutated in this?

Answer 12

Associated with microtubule function
Alpha tubulin
MAP

Question 13

16. What do the first migrations of neurons do?

Answer 13

Delineate the boundaries of cortical layers

Question 14

1. What do the earliest migrating neurons from the ventricular zone form?

Answer 14

Preplate

Question 15

18. Later migrating neurons form?

Answer 15

Cortical layer

Question 16

19. What is the preplate composed of?

Answer 16

Cajal retzius (CR) cells in marginal zone
Subplate neurons below

Question 17

20. What does the cortical layer sit between?

Answer 17

Marginal zone and subplate

Question 18

21. What does a Reeler mutation (naturally occurs in mice) effect and why?

Answer 18

CR cells by causing disruption in layering because migrating neurons fail to stop

Question 19

22. What happens over time to radial glia?

Answer 19

They become depleted

Question 20

23. What becomes adult neural stem cells?

Answer 20

A subset of radial glia cells is put aside to become astrocytes-like

Question 21

24. Where are the 2 main stores of adult SCs?

Answer 21

Subventricular zone to olfactory bulb

Dentate gyrus of hippocampus – spatial memory

Question 22

25. What is tangential migration?

Answer 22

Key neuronal subpopulations migrating from other areas (not radial)

Question 23

26. What is the subpallium?

Answer 23

Part of the telencephalon

Question 24

27. What do precursors of these cells do?

Answer 24

Migrate tangentially over long distances

Question 25

29. How do anterior (superior) rhombic lip cells migrate?

Answer 25

Tangentially over surface of developing hindbrain both in A-P and D-V axis

Question 26

30. How do posterior rhombic lip cells migrate and what do they form?

Answer 26

Ventrally to give rise to the pontine nucleus and inferior olives

Question 27

31. How do granule cell neurons migrate?

Answer 27

Outside  inside - Proliferative layer is on outside - Radial migration to inside (parallel fibres)

Question 28

Cerebellum is a derivative of what?

Answer 28

• Derivation of neural crest cells derived from roof plate

Question 29

What characteristics do rhombic lip cells have?

Answer 29

• Rhomic lip cells are also highly proliferative and have proliferative daughters

Question 30

Where does the cerebellum also derive neurons from?

Answer 30

* Major neuronal types are also derived from the equivalent region of the developing hindbrain * This region is called the rhombic lip