Which of the following is not seen after nerve transection?
Ans. is 'd' i.e., Neuroma in continuity Morphology after nerve transection* The morphologic hallmarks of axonal neuropathies produced by cutting a peripheral nerve, results in a prototypical pattern of injury described as Wallerian degeneration.* Portions of axons that are distal to the point of transsection are disconnected from the central neuron and degenerate.* Within a day of injury, the distal axons begin to fragment and the associated myelin sheaths unravel and disintegrate into spherical structures (myelin ovoids).* Macrophages are recruited and they participate in the removal of axonal and myelin debris.* Regeneration starts at the site of transsection with the formation of a growth cone and the outgrowth of new branches from the stump of the proximal axon.* Schwann cells and their associated basement membranes guide the sprouting axons, which grow at about 1 mm per day, toward their distal target.* Continuous pruning of the sprouting axons removes misguided branches.* The Schwann cells create new myelin sheaths around the regenerating axons, but these myelin internodes tend to be thinner and shorter than in the original ones.* The repair process is successful only if the two transected ends remain closely approximated.* A failure of the outgrowing axons to find their distal target can produce a "pseudotumor" termed traumatic neuroma-- a nonneoplastic haphazard whorled proliferation of axonal processes and associated Schwann cells that results in a painful nodule.Note* Neuroma in continuity is seen in Axonotemesis in which nerve is not transected. Complete transection (neurotmesis) produces neuroma (but not in continuity).
Morphologic pattern of wallerian degeneration
Myelin ovoids
Painful neuroma
Neuroma in continuity
C.N.S.