Axon swellings produced in vivo in isolated segments of nerves

Abstract

Within 3–5 hrs after cutting rat and cat sciatic nerves into segments which had no connection with the cell body, club-shaped axon swellings were observed at both ends of the segments. The swollen portion of these axons showed increased histochemical reactions for DPN-diaphorase, lactic dehydrogenase, malic dehydrogenase, succinic dehydrogenase, and protein; the increase lasted for 24–48 hrs after the nerve was cut. The swollen axons were morphologically and histochemically similar to, but never as markedly changed, as those observed in the proximal stumps of severed nerves. The development of axon swellings was prevented by depolarization of the entire segment with KCl; however, if KCl was applied selectively to the stumps of the segment, it appeared to intensify rather than prevent the swelling. It was also noted that the extent of axon swelling was inversely proportional to the length of the segment. These observations suggested that the development and extent of axon swelling was related to the intensity of local injury currents in the tissue. Innerhalb von 3–5 Std nach Zerschneidung des Nervus ischiadicus von Ratten und Katzen in Segmente, die keine Verbindung mit dem Zellkörper besitzen, sind zylinderförmige Axonschwellungen an beiden Enden der Segmente zu beobachten. Der angeschwollene Teil dieser Axone zeigt verstärkte histochemische Reaktionen auf DPN-Diaphorase, Milchsäure-Dehydrogenase, Apfelsäure-Dehydrogenase, Bernsteinsäure-Dehydrogenase und Protein; dieser Anstieg hält 24–48 Std nach der Durchtrennung des Nervs an. Die Axonschwellungen sind sowohl morphologisch als auch histochemisch ähnlich — jedoch niemals in gleich starker Ausprägung — jenen, die in den proximalen Stümpfen von verletzten Nerven beobachtet werden.