NEUROGENESIS Flashcards
As cells differentiate, what also occurs?
They move laterally
Do all daughter cells differentiate and migrate?
No, some are retained in the ventricular zone.
What is the function of those that do not differentiate?
Progenitors give rise to radial glia. Radial glia are neural stem cells. They provide a pool of undifferentiated cells that are needed to build up the nervous system over embryogenesis.
The early neural tube is one cell thick and made up of neurepithelium. As they become radial glial, they proliferate and their nuclei undergo what?
Interkinetic Migration.
The nucleus moves depending upon which stage of the cell cycle they are in. In G1 and S phase, the nucli move away from the lumen. In M phase the nuclei is close to the lumen.
Radial glia can divide to become what?
Symmetrically - radial glia
Asymmetrically - neuronal precursor
What determines whether a daughter of a radial glia will be radial glial or neuronal?
- Plane of division - meridian or equator
2. Notch signalling
How was Notch Signalling studied?
Normally in the fly, there are clusters of cells that have activated proneural genes. These cells are competent to become neurons but not all of them do. In a proneural mutant, no cells become neurons. In a neurogenic mutant (Notch-/-_ more neurons are formed.
So if the cell does not see Notch, then more neurons form. Ie Notch is normally required to prevent cells from become a neuron.
What can be said about the effect of Notch?
A cell expressing Notch will not form a neuron.
A cell in in which Notch activity is repressed will form a neuron.
This is a process called lateral inhibition, a special kind of induction that makes initially similar cells different from one another.
What exactly is Notch?
A receptor.
How does lateral inhibition begins if all cells are initially similar?
A random bias is introduced.
