Contraction of Traumatized Nerve Cell Processes

Abstract

Studies were performed on living isolated mollusk (Lymnaea stagnalis) neurons. The aim was to investigate the contractile activity of traumatized neuron processes. Retraction of process in Ringer’s solution was seen in 90% of cases. The characteristic club-shaped formation, i.e., the retraction bulb, was a marker of contraction. The rate of process contraction ranged in different neurons from 0.03 to 9 μm/min. Increases in process diameter by an average of 35% occurred during normal linear contraction, while increases in cell body volume were by an average of 30%. Three forms of contractile activity were identified: linear contraction, isometric contraction (with decreases in process width with unaltered length), and mixed contraction. It is suggested that the mechanism of retraction is involved in the formation of diastases on nerve transection and in lesions to the conducting pathways of the brain. Nerve diastases formed not only as a result of the elastic properties of its connective tissue sheaths and glia, but also because of retraction of nerve fibers.