Neurogenesis Flashcards
How does the neural tube form?
- Neural plate folds
- neural folds fuse into a hollow neural tube
What does the anterior section of the neural tube form?
Major brain regions
What does the posterior section of the neural tube form?
Spinal cord
What is the ventricular zone?
The area of neural tube that is initially only 1 cell thick
Why does the ventricular zone contain rapidly dividing precursors?
TO INCREASE THICKNESS OF THE ZONE
What do the daughter cells of the VZ differentiate into?
Neurons & glia
What occurs during pre-neurogenesis in the VZ?
- early cell division of NEUROEPITHELIAL cells is SYMMETRIC
- produces 2 eqivalent daughter NECs
What occurs during early neurogenesis in the VZ?
-ASYMMETRIC cell divison gives rise to different daughters:
*neural progenitor RGCs (radial glial cells)
*neurons
What is asymmetrical division in neurogenesis?
(two daughter cells with different cellular fates)
A tilted mitotic spindle correlates with unequal division of centrosomes.
- older stays with the RGC stem cell
- newer goes with the neuron
What cell type creates a scaffold for migration?
Radial glial cells (RGCs)
How do RGCs create a scaffold for migration?
Span from the VZ to outer Pia layer of developing brain
What happens to EARLY neurons in the VZ?
leave the VZ & migrate to form the deepest layers FIRST
What happens to LATER neurons in the VZ?
travel progressively further to build outer layers (i.e. closer to pia)
Name a factor that controls the final position of neurons migrating from the VZ
Environmental cues
What is reelin?
What is its function?
A glycoprotien secreted from the pia layer in early cerebellum development.
Enables neuronal migration thru already existing layers!
What are mouse ‘reeler’ mutants?
Mice that have cerebellar dysfiunction.
BECAUSE neuron layers are INVERTED (inside-out)
What are Homeobox transcription factors?
One of the regulators of RGC proliferation vs expression of pro-neural genes
(a.k.a CONTROLS WHICH TYPE OF CELL THE NEUROEPITH. CELLS WILL DIFFERN. INTO!)
Explain how neurogenesis is possible in ADULT mammals
New CNS neurons can be generated
-ventricular (neuronal) stem cells have been found!-
Explain neurogenesis in songbirds
Young birds learn call from adult tutor
Once call is CRYSTALLISED, control & memory remain intact
In subsequent years, their performance requires annual regeneration of the PREMOTOR & MOTOR regions of CNS [because they forgot the song]
(i.e. annual increase in neurogenesis) –> triggered by increased testosterone
What are the main benefits of neuronal stem cells in adults?
release of TROPHIC (GROWTH) FACTORS!
- support remaining neurons
- DO NOT create new synaptically-connected neuron replacements.
What are neuronal stem cells attracted to?
NSCs are highly migatory
Attracted by processes involved in brian pathologies
- inflam
- astrocyte activation
- new blood vessel formation
