ALTERATIONS IN THE SPINAL GANGLION CELLS 

 FOLLOWING NEUROTOMY. 



Bt 



?!. WALTER RANSOX. 



From the Anatomical Lahoratonj of the Unlccrsity of Chicago. 



With Six Fioures. 



Introductiox. 



The work of Nissl, Liigaro, and a considerable nnmber of other 

 investigators has priced iis in possession of the essential facts con- 

 cerning the iiner strnctnre of the spinal ganglion cells both nnder 

 normal and pathological conditions. It is not the purpose of this 

 paper to supplement in any way the excellent cytological studies 

 of these ear'ier investigators, but rather to answer certain questions 

 suggested by an investigation recently published from this laboratory 

 under the title of "Retrograde Degeneration in the Spinal Nerves" 

 (Ranson'06). 



It was shown that two months after the section of the second 

 cervical nerve in young rats 52 per cent of the nerve cells had dis- 

 appeared from the corresponding ganglion. The average loss was 

 4412 nerve cells, the average normal ganglion containing 8451 such 

 cells. Since there w^ere only 1500 medullated fibers in the nerve 

 at the time of the operation on 12-day-old rats, it is remarkable 

 that its division should have caused the destruction of so large a 

 number of cells. 



Still more difficult to explain is the fact that the degeneration 

 of 52 per cent of the ganglion cells was accompanied by a loss of 

 only 17 per cent of the dorsal root fibers. In the hope of finding 

 an explanation for these results, the literature dealing with the 

 architectural relations of the afferent elements entering into the 

 formation of the spinal nerves, has been carefully reviewed in another 

 paper (Ranson '08). 



From a study of the literature, it is evident that the cells of the 



The Journal of Compakative XEUitoiAXiY and Psychology. — Vol. XIX, No. 1. 



