lecture 8- neuronal migration Flashcards
why is the early neuroepithelium described as pseudostratified
it looks like there are different layers due to the migration of mitotically dividing nuclei
where do mature neurons accumulate
in the mantle zone
how do mature neurons get to the mantle zone
by migrating radially from the ventricular zone
describe the radioactive dating experiment
inject 3H into newly synthesised DNA and then take samples
only the cells that have fully differentiated and left the cell cycle will show the 3H
they found that a different layer of differentiated cells was found between injecting at day 12 compared to day 15
what does the radioactive experiment suggest
that neurons ‘born’ at different times migrate to different layers of the cortex
which layers do the first born neurons occupy
deepest layers
which layers do the later born neurons occupy
uppermost
how is each layer of the cortex characterised
by different transcription factors so different cell fates
how can heterochromic transplants be used to test whether fates of neuronal precursors are fixed or plastic
early precursors transplanted to older hosts adopt fate of the cells born at the same time (plastic)
later born precursors when transplanted to a younger host adopt the fate they would have usually been (fixed)
what is lissencephaly and how is it caused
smooth brain
mutations in microtubules
what does the preplate contain
cajal retzius cells
subplate cells
how does the structure of the preplate change with the migrating neurons
the migrating neurons sit inbetween the two cell layers
what is the role of reelin
tells migrating cells when to stop
what are tangential migrations
where the cells migrate laterally instead of radially
what percentage of the brains neurons are in the cerebellum
80.2
