RETROGRADE DEGENERATION IN THE SPINAL 



NERVES. 



S. WALTER RANSON. 



(From the Neurological Laboratory of the University of Chicago and the Anatomical Laboratory of 



the St. Louis University.)^ 



I. Summary of the Literature. 



Retrograde degeneration, sometimes also spoken of as "ascend- 

 ing degeneration" (Fleming '97) and " indirect Wallerian degenera- 

 tion" (van Gehuchten '03), is a process resulting in the de- 

 struction of that portion of a divided fiber which is still connected 

 with its cell of origin. Such cellulipetal changes are not in accord 

 with the law of Waller, which requires that of a divided nerve 

 fiber only the portion severed from its trophic center should dis- 

 integrate, while all the rest of the neurone remains intact; never- 

 theless, this retrograde degeneration has been observed by a large 

 number of investigators; it has been found in the cerebral as well 

 as in the spinal nerves and occurs under certain conditions in 

 various fiber tracts of the central system. 



The investigations, which lead to the discovery of this form of 

 degeneration, were carried out in the first instance upon the nerves 

 in the central stumps of amputated limbs and upon the associated 

 segments of the spinal cord. Experimental amputation and nerve 

 resection in animals have served to confirm the observations made 

 on human material and to eliminate complications introduced by 

 the cause of the amputation or by the terminal disease. Since 

 the cellulipetal changes resulting from the section of the spinal 

 nerves are typical of retrograde degeneration, it has not seemed 

 desirable to complicate matters by a review of the literature on 

 similar changes in the cerebral nerves, nor in the fiber tracts of the 

 central system. The observations along these lines have been 



iWhile at the St. Louis University the writer received very valuable assistance, both in the 

 operations and the enumerations, from Dr. Fred. B. VVhittiker, to whom he is especially indebted. 



