Lecture #10 Flashcards
(39 cards)
what are five characteristics of adult stem cells?
- cells that are undifferentiated
- they can self renew and differentiate to become more specialized
- maintain cell populations facing neuronal death
- help healing
- counteract the aging process
what is homeostasis?
the ability to regulate internal conditions in organs or tissues, usually acting on several mechanisms that are under the control of feedback signals
how can you demonstrate the stemmwness of a single element?
clonogenic assay
if you compare the number of neurogenic niches along evolution, what do you see?
we can observe a substantial reduction in number
in mice what happens to young neuroblasts migrating through the RMS when they are in proximity to the OB?
they can leave the stream in all directions and enter the glomerular (GL) and the peri-glomerular (GLC) layers where they finish the complete differentiation into inhibitory neurons
what are generated by the sub ventricular zone, and why are they important?
inhibitory neurons - if they’re absent in the OB the mouse cannot sense the external environment
what niche can be found in the adult hippocampus?
the subgranular zone of the dentate gyrus
what is the subgranular zone of the dentate gyrus?
a small region in the medial part of the brain were we have a particular subset of NSCs
what do the cells in the subgranular zone of the dentate gyrus differentiate into?
progenitors that migrate hundreds of microns before starting the final differentiation into excitatory neurons
describe the type II cells in the subgranular zone:
intermediate progenitors that can undergo one or two rounds of cell proliferation before their final differentiation into type III cells
describe type III cells in the subgranular zone:
similar to neuroblasts - start to extend their axons and dendrites acquiring the full characteristics of a neuron → at the end they will integrate into the dendrite gyrus where they are very important for hippocampal functionality
what is the key difference between cells of the SVZ and the hippocampus?
SVZ: adult NSCs differentiate into GABAergic and some dopaminergic interneurons (both inhibitory neurons)
hippo: NSCs differentiate into excitatory neurons
describe the three types of dendate gyrus neurons:
type I: truly NSCs
type II: intermediate progenitor cells the can make some rounds of proliferation and then finally differentiate
type III: neuroblasts - cannot proliferate but have not completed maturation
describe the three types of cells in the SVZ:
type A: neuroblasts (immature neurons)
type B: NSCs
type C: iPSCs
describe the niche in the dendate gyrus (DG):
NSCs are in close contact with vascular epithelial cells astrocytes, and type III cells that differentiate into glutamatergic neurons
describe the niche in the SVZ:
the ependymal layer forms a sort of “floor” that separates the niche from the ventricular cavity → there’s a complex vasculature which is fundamental for the regulation of the neurogenesis in the niche and there are also astrocytes to support this niche
what do B cells of the SVZ express?
markers that are shared wit astrocytes - GFAP (typically associated with activated astrocytes)
describe the projections B cells of the SVZ can send:
can extend very short cytoplasmic bundles the enter between the ependymal cells and can imitate contact with the cerebrospinal fluid
they can also extend very long cytoplasmic bundles the enter in contact with the blood circulation surroinding the niche
what is the function of the type B cells of the SVZ?
they can sense at the same time what is inside the CSF and what is circulating in the blood → forms part of the BBB and interacts with the ventricular cavity
describe the type C cells of the SVZ:
lose their GFAP positivity and start to proliferate - after 2-3 rounds the differentiate into type A cells and leave the SVZ along the RMS
describe microglia in the SVZ:
uniformly distributed and its role in regards to the regulation of NSCs is still unknown - professor thinks maybe for cell proliferation
when observing the formation of NPCs, what was seen after embryonic day 12.5-13?
after symmetric cell division some neuroepithelial cells became quiescent and they stayed in this quiescent state for the entire embryonic life → then they start to acquire proliferative capacity when the brain will be an adult, becoming the NSCs of the SVZ
which neuroepithelial cells will become the lateral ventricle?
neuroepithelial cells in the lateral embryonic eminence
which neuroepithelial cells will become the dorsal part?
neuroepithelial cells entering G0 during the embryonic life
