Regeneration Flashcards
What causes tail regeneration in xenopus tadpoles
BMPs during a critical refractory period
What is the result of a peripheral nerve injury close to the soma
More likely to result In cell death - retraction of processes, chromatolysis
What is the result of a peripheral nerve injury to the proximal axon
Reorganisation and re-expression of immature features i.e. tubulins
What id the result of a peripheral nerve injury to the distal axon
Disintegration and death - macrophages move in to clear debris
What effect does peripheral nerve injury have on the denervated muscle
Atrophy of muscle
AchR revert to their embryonic types - increased levels of MUSK
How is a peripheral nerve injury regenerated
Macrophages remove damaged myelin
Mitosis of Schwann cells supply growth factors causing formation of Band of Bunger - rows of Schwan cells to guide axon regrowth
Undamaged nearby neuron in area sends projections to cover the damage and target denervated muscle
How do crush and cut injuries differ in the ability for regeneration
Crush - ECM and basal lamina remain intact allowing for easier regeneration
Cut - Makes regeneration harder/impossible - sutured nerves may not regrow accurately
What are the results of spinal cord injuries
Sprouting followed by failed regeneration and subsequent degeneration - cysts and glial scars form
Why is regeneration so poor
Inhibitory myelin - CNS neurons avoid oligodendrocytes in vitro - myelin proteins produce nogo-a which inhibits axon growth
What is the role of nogo-a
Critical inhibitory protein in CNS - KO or anti-nogo leads to partial decrease in inhibition of axon regrowth
What role do astrocytes have in preventing regeneration
Formation of glial scarring
attachment to astrocytes impairs their regeneration
What are spinal bridges
Artificial structures that bypass lesions - filled with growth factors, ECM and synthetic matrix
