REGENERATION OF NERVE 



773 



nerve is cut and then sutured, a certain amount of distortion of the 

 pattern is inevitable. The mechanical apposition of central and 

 peripheral stumps is, of course, much more nearly perfect in the 

 crushed nerve than in the cut nerve, however exact the suturing 

 may be (Osborne and 

 Kilvington). Yet, even 

 after crushing or liga- 

 tion of nerves, or after 

 section and suturing, 

 the regenerating fibres 

 do not pass straight 

 through the scar tissue 

 from the central to the 

 peripheral stump, but 

 cross and mingle, ap- 

 parently in the- most 

 inextricable confusion 

 (Feiss) (Fig. 272). This 

 is due to the prolifera- 

 tion of cells in the scar 

 which run in all direc- 

 tions, and show no 

 signs of following the 



Fig. 272. Regenerating Fibres crossing in the Scar 

 after Ligation of a Dog's Sciatic Nerve 165 Days 

 previously. Weigert-Pal stain. Drawn under oil- 

 immersion (Feiss). 



parallel arrangement of the nerve-sheaths in the central or the 

 distal segment. These being formed before the regenerating 

 nerve- fibres, the latter must necessarily grow also in all direc- 



EP- 



Ext: R> P i,teol' 



This, however, is a 

 local phenomenon. 

 Beyond the scar the 

 arrangement of the 

 regenerating axis- 

 cylinders recovers 

 its regularity, and 

 the amount of dis- 

 tortion of the nerve 

 pattern, as indicated 

 by histological ex- 

 a m ination and 

 functional tests, is 

 by no means so 

 great as the com- 

 plete effacement of the pattern in the scar might appear to promise. 

 That the degenerated peripheral stump directs the growth of 

 the axons from the central stump in some other than a merely 

 mechanical way is evident from the experiments of Langley on 



Fig. 273. Semidiagrammatic Representation of Longi- 

 tudinal Section through Neuroma or Scar produced by 

 ligating the Sciatic Nerve with Catgut, and crushing it 

 with a haemostat just above its Division into the Ex- 

 ternal and Internal Popliteal Nerves. Weigert-Pal 

 preparation (Feiss). 



