xvi Journal of Comparative Neurology, 



The Initial Stages of the Degeneration of NerTC Fibres. ' 



The phenomena attendmg the degeneration of the nervous tissues 

 have long been matters of the highest interest to the pathologists, and 

 especially since the recent studies on the regeneration of nerve fibres 

 any facts bearing on the histological processes involved in degeneration 

 have an added interest. Numerous pathologists have described the 

 changes observed in the structure of the nerve fibre in the various cen- 

 tral and peripheral neuroses and now Dr. Klippel coordinates these 

 morbid processes and finds that they may be resolved into a single pro- 

 cess which is essentially the same in all cases. 



The first stage in the degeneration of the nerve fibre is apparently 

 a remarkable hypertrophy of the nerve tube. It is not, however, a true 

 hypertrophy, but a tumefaction, the first stage of a lesion essentially 

 destructive. The myelin becomes hyaline and loses in the axial por- 

 tion next to the axis cylinder the concentric appearance so characteris- 

 tic of the normal fibre. This portion also becomes granular and stains 

 more intensely than the normal myelin, though not so dark as the axis 

 cvlinder. The fact that this disintegration of the myelin begins ax- 

 ially and not peripherally indicates that the morbid process has its ori- 

 gin in the axis cylinder. And in fact simultaneously with the changes 

 just described the axis cylinder also exhibits hypertrophy with a pecu- 

 liar change of form. In transection it appears no longer as a circular 

 dot in the centre of the sheath but as a greatly enlarged and variously 

 shaped figure, a rod, a spiral, a circle or a sigmoid. In tracing a fibre 

 from section to section this alters in form showing that the contour is 

 flexuous and that the fibre is still in a state of degenerescence. Later, 

 in the penultimate stage of the process, granular fragmentation occurs 

 to be followed by the final complete resorption. 



The degenerative process of the nerve fibre may then be divided 

 into three stages, the swelling and deformation of the axis cylinder with 

 the figures just mentioned, the granular disintegration and fragmenta- 

 tion of the axis cylinder together with the liquefaction of the myelin 

 from the centre toward the periphery, and finally complete resorption. 



In diseases like general paralysis the cells of the cornua of the 

 cord are affected in a manner strictly analogous. The study of the 

 early stages of this process is of course attended with the difficulty aris- 

 ing from the scarcity of material for histological examination taken at 

 the proper stages of the disease, yet a goodly number of cases are on 



^ Klippei,, M. Comment debutent les degenerescences spinales. Arch, de 

 Neurologie, 2 Serie, I, i, Jan., 1896. 



