REGENERATION OF A DEGENERATED NERVE Provided there is a neunlemmal sheath, a degenerated nerve may regenerate In a case

neurilemma containing large number of phagocytes, digesting The ingested material. Such a tube is called a "ghost tube", a term coined by Edward Sharpey- Schafef B. Changes in The proximal part 1. The same degenerative changes are seen m The proximal stump, but only upto The node of Ranvier nearest to The injury 2 The cell soma also shows changes ll shows chromatolysis (degeneration of The Nissl granules) and some swelling. REGENERATION OF A DEGENERATED NERVE Provided there is a neunlemmal sheath, a degenerated nerve may regenerate In a case of satisfactory regeneration, the steps are as follows : 1 The axis cylinder from the proximal stump, grows and sprouts out from the cut end The emerging sprout may be branched [N B (a) In place, where the neunlemma is absent, there can be no regeneration Nerve fibers of The CNS therefore, once degenerated, never regenerate as these nerves hava no neurilemma (b) When a peripheral nerve fiber is inured regeneration occurs following The degeneration no doubt, but if the nerve cell body (soma) dies, no regeneration is possible (c) If an axon of the brain degenerates, there will be no regeneration, as staled above But in addrtion, retrograde degeneration occurs severely, ultimately causing the dealh of the soma As mentioned earlier, (chap l. sec.XA), owing to The absence of minosish such dead soma cannol be replaced by fresh nerve cells). 2 Provided the distance bet ween the proximal and the distal portions are not great h the sprout or a branch of The sprout, enters the 'ghost tube' and keeps on enlarging, at a rate little over 1 mm/day, tilt it reaches The terminal end and establishes connection with The motor end plate The cells of Schwann cause myelimation the axis cylinder. The growth of the axis cylinder 15 due to vigoros protein synthesis by The nerve cell body (soma). The newly synthesized protein travels into The axon APPLIED PHYSIOLOGY 1 If the gap between the cut ends of The nerve, that is. The distance beiween the proximal and peripheral slumps is great, eiceedrng 3 mm, regeneration r. difficull. because bridging of The gap by neuntemma becomes difficult Regeneration in such cases may be helped by surgical procedure (sutunngthe cut ends of the nerve). Such surgical procedures should be taken up quickly, otherwise the motor end plate may alrophy 2, The sprout emerging out of the proximal stump, in some cases,