THE NON-CENTRIFUGAL DEGENERATION OF SEVERED PERIPHERAL NERVE

Abstract

The cut left sciatic nerves of leopard frogs kept at 18-20[degree]C lost the capacity to transmit impulses to their attached gastrocnemii 13-14 days after the operation. This loss, measured by muscle twitches, occurred simultaneously throughout the length of the peripheral stump. In frogs kept at 12-15[degree]C, the physiological degeneration did not occur until the 17th day after the cut. The action potentials from these nerves declined and disappeared simultaneously throughout the length of the nerve. The progressive increase of threshold with time, which occurs in the severed nerve, also appears simultaneously throughout its length. Examination of the degenerating nerves with a modified Sudan III-haematoxylin stain showed the myelin degeneration was not progressive from the cut end. Discrepancies between these findings and previous ones are attributed to use of adequate stimuli (in view of branches, and irregular motor fiber distribution in the frog sciatic) and to elimination of the area of traumatic degeneration at the cut end of the nerve. These results were confirmed in rats (with an accelerated time scale), and agree with the results of others on various nerves in cats and monkeys (using both histo-iogical and action potential studies).