lec 17. regeneration Flashcards
what happens to severed/crush peripheral nerves?
if the damage is close to the cell body it kills the cell
if the damage is midway, then the proximal axon and expressed features of developing neurons and get recovered while the distal part degenerates
wallerian degeneration
when peripheral nerve is cut or crushed and the distal part dies
muscle atrophy
wasting of muscle due to degeneration of motor neurons (peripheral nerves)`
steps of regeneration of peripheral nerves
1) oligodendrocytes progenitors proliferate into schawnn cells
2) formation of bands of bungner (schwann cells +growth factors + axonal trophic factor)
3) regrowth along schwann cells and sprouting
what occurs in damaged CNS neurons (eg. spinal cord injury) ?
sprouting of axons and dendrites that dont go anywhere -> failed regeneration
complete degeneration + massive glial scars and cysts
oligodendrocytes instead make inhibitory factors (nogo-a)
NOGO
binds to nogo receptors and inhibits growth of CNS neurons. Nogo KO partially reduces inhibitions
regeneration animals like fish and salamanders lack nogo
optic cup
forms on the diencephalon and goes on to form the neural retina and neurtal epithelium. It also contacts the surface ectoderm which invaginates to form the lens
inner optic cup
stem cell like, can self renew or differentiate into sensory cells of the retina
-> these are neuroblasts which differentiate in ways to give the layers of the retina
outer optic cup
progenitor cells give rise to retinal pigment epithelium at eh back of the retina
macular degeneration
age related degeneration of pigment epithelial progenitors that become depleted or exhausted
surface ectoderm
contains stem cells that give rise to lens which switches off all TFs except for crystallin and throws out nucleus
-> we need stem cells to generate new lens throughout life, depletion can lead to cataracts
