This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: C.N.S., Subject name: Medicine
[{'content': 'Which of the following is not seen after nerve transection? \nSelect and explain. \nA. Morphologic pattern of wallerian degeneration, B. Myelin ovoids, C. Painful neuroma, D. Neuroma in continuity', 'role': 'user'}, {'content': 'Answer: D \nExplanation: 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).', 'role': 'assistant'}]