THE RECOVERY OF DIAMETER AND IMPULSE 



CONDUCTION IN REGENERATING 



NERVE FIBERS 



By Charles M. Berry and Joseph C. Hinsey 



Department oj Ayiatomy, Cornell University Medical College, New York, N. Y. 



The primary purpose of these experiments was to study those prop- 

 erties of regenerating fibers which could be observed oscillographically 

 and related to histological controls. Therefore, the contours of the 

 action potentials, the conduction velocities of the impulses, and fiber 

 diameters were followed in a series of cat nerves. The recovery of 

 these properties might be considered to be a process of reconstitution or 

 maturation, as opposed to the longitudinal outgrowth of the fibers, and 

 since these properties continued to change over long periods of regenera- 

 tion, measured in years, the experiments were spread over a wide range 

 of time, from a few days to more than three years. 



Having observed the effects of time (which is undoubtedly the most 

 important factor in the reconstitution of fibers distal to a suture) , we 

 extended the experiments to include the effects of crushing the nerves 

 compared to section and suture; the effects of delaying the suture after 

 transection; and the effects of cross-suturing nerves containing fibers 

 of different fiber diameters. The importance of these factors has been 

 reemphasized in recent publications. The growth of fiber diameters 

 in the distal stump over a one year period has been carefully plotted 

 by Gutmann and Sanders.^ Furthermore, they showed differences in 

 recovery between crushed and sutured nerves. The influences of phy- 

 sical stresses in the '''union" tissue described by Weiss- show the im- 

 portance of the type of junction between central and distal stumps. 

 The effects of delaying the suture after section of a peripheral nerve 

 were studied by Holmes and Young,^ and the effects of cross-suturing 

 visceral and somatic nerves were reported by Simpson and Young.* 

 Young and his co-workers have paid special attention to the connective 

 tissue sheath diameters in the distal stump. 



METHODS AND RESULTS 



Action Potentials from Regenerating Nerves 

 Cathode-ray oscillographs were taken from regenerating tibial, 

 peroneal, and saphenous nerves of 64 cats. The nerves were transected 



(559) 



