Nucleic Acid and Protein Metabolism of the Axon

Abstract

Several factors have contributed to the generally held notion that the axon depends wholly upon its cell body for all of its soluble and structural proteins. Historically, the nineteenth century experiments of Waller and Türck, demonstrating the importance of continuity between axon and cell body for preserving structural integrity of the axon, were perhaps most compelling in structuring subsequent thinking about the axon’s dependency. A second factor was the concept of axoplasmic flow, a proposed mechanism whereby the perikaryon supplies the axon with its metabolic needs. This was a logical hypothesis that followed directly from the studies involving axonal degeneration. Indeed, Barker states in his textbook published in 1899,⁽³⁾: “To explain the influence of the cell body upon the fibre, Goldscheider has advanced a very ingenious hypothesis. He suggests that it is most probable that there is an actual transport of a material, perhaps a fermentlike substance, from the cell along the whole course of the axone to its extremity, and first through the influence of this chemical body the axone is enabled to make use for its nutrition of the material placed at its disposal in its anatomical course.” The phenomenon of axoplasmic flow is now well established, owing to the classic experiments of Weiss and co-workers that stimulated the large number of studies that followed subsequently (see Chapter 18, Vol. II of this Handbook).However, in view of the paucity of information at that time and the lapse of more than 40 years before the phenomenon was finally demonstrated, Goldscheider may be credited with having had profound intuitive insight.