L7c: Neurogenesis

what are individual spinal progenitors also known as?

multipotent stem cells

what is the potency of radial glial cells?

unspecialised multipotent stem cells that can make a large range of cell types

how do we know the potency of RGCs?

take neuroblast from drosophila or RGC and culture them alone to see what cells are produced

how can you investigate what types of cells a stem cell can differentiate into?

lineage tracing

retrovirus containing lacz encodes enzyme beta galactosidase blue marker

marker used to identify beta galactosidase production

what controls what cell type a progenitor divides into?

determined by the time differentiation occurs

what are cell fate switches in motor neuron progenitor domains of the spinal cord?

birth order influences neural subtype differentiation

first born differentiate as motor neurons

later cells differentiate into glial

what are oligodendrocytes?

neuroglia whose main function is to support axons within the CNS

similar to schwann cells in the PNS

what are the cell fate switches in pMN domains of the ventral hindbrain?

different neurons at different times

early visceral motor neurons in mice

late serotonergic neurons in mice

birth order influences neural identity

where are the first and last born progeny relative to GMCs in drosophila?

last born on the outer edges while first born are located inwards

what is the potency of drosophila neuroblasts and what does this mean?

each neuroblast is multipotent as they can produce a wide range of neurons and glial cells

each neuroblast creates a characteristic clone of neurons

what influences neuron identity in drosophila GMC?

transcription factors released according to birth date

first born - hunchback

last born - castor

how are the expression patterns different in GMCs with different time stamps?

all neurons have the same time stamp

all top neurons become motor neurons due to the same time stamp

influences spatial pattern

proprioceptive neurons target interneurons

what is the switch mechanism that causes the temporal sequence in drosophila?

when neuroblast first forms it expresses hunchback, this is later inherited

stays in the GMC but stops being expressed in the neuroblast which divides and expresses the next signal

what is the most likely cause of this switch mechanism?

complex regulatory gene interactions

cell division or molecular clock

may be linked to cell cycle machinery

how are neurons arranged in the cerebral cortex?

cell bodies or neurons in gray matter with neurons arranged in layers called lamina

6 layers of neurons superficial to deep (in to out)

different neuronal function in each layer

how are neurons in different layers different?

functionally and morphologically different

birth order determines arrangement but in opposite fashion

new in superficial

at what stage is cortical fate determined?

progenitor stage due to ferret experiments

heterochronic cell transplantation shows premigratory precursors are already programmed with neural fate

what is the ferret experiment?

RGC transplanted into brain of ferret at different ages

found that newly generated precursor contained its own time stamp and would not migrate out to the periphery

same as drosophila

what molecular switches are there?

early neural types require Ikaros/Hb

regulated by coup-tfl/Svp