Neuronal migration in CNS development Flashcards
- What is pseudostratified?
Early neuroepithelium
- How thick is the early neuroepithelium?
1 cell thick
- How do the nuclei move?
Up and down
- On what surface does the M phase of cell cycle occur?
Ventricular surface
- How is the division early on in these cells?
Symmetrical
- Early phase expands neuroepithelium
- What is produced when the division becomes asymmetric?
cytoplasmic components allocated differently
Radial glia (stem cell like & spread apical to basal surfaces) Neuronal precursor
- What do these neuronal precursors do to then become mature neurons?
Migrates out up radial glial fibres to upper areas called the mantal zone and here becomes a mature neuron
- Where do cells ‘born’ later move to?
The top/higher/outside
- What do heterochronic transplant test?
Tests whether the fates of neuronal precursors is plastic or fixed
- What happens if early precursors are transplanted to older host?
Fate is plastic
- What is lissencephaly?
Brain surface smooth due to improper/defective neuronal migration
- What genes are mutated in this?
Associated with microtubule function
Alpha tubulin
MAP
- What do the first migrations of neurons do?
Delineate the boundaries of cortical layers
- What do the earliest migrating neurons from the ventricular zone form?
Preplate
- Later migrating neurons form?
Cortical layer
- What is the preplate composed of?
Cajal retzius (CR) cells in marginal zone Subplate neurons below
- What does the cortical layer sit between?
Marginal zone and subplate
- What does a Reeler mutation (naturally occurs in mice) effect and why?
CR cells by causing disruption in layering because migrating neurons fail to stop
- What happens over time to radial glia?
They become depleted
- What becomes adult neural stem cells?
A subset of radial glia cells is put aside to become astrocytes-like
- Where are the 2 main stores of adult SCs?
Subventricular zone to olfactory bulb
Dentate gyrus of hippocampus – spatial memory
- What is tangential migration?
Key neuronal subpopulations migrating from other areas (not radial)
- What is the subpallium?
Part of the telencephalon
- What do precursors of these cells do?
Migrate tangentially over long distances
- How do anterior (superior) rhombic lip cells migrate?
Tangentially over surface of developing hindbrain both in A-P and D-V axis
- How do posterior rhombic lip cells migrate and what do they form?
Ventrally to give rise to the pontine nucleus and inferior olives
- How do granule cell neurons migrate?
Outside inside
- Proliferative layer is on outside
- Radial migration to inside (parallel fibres)
Cerebellum is a derivative of what?
• Derivation of neural crest cells derived from roof plate
What characteristics do rhombic lip cells have?
• Rhomic lip cells are also highly proliferative and have proliferative daughters
Where does the cerebellum also derive neurons from?
- Major neuronal types are also derived from the equivalent region of the developing hindbrain
- This region is called the rhombic lip
