The neurotubular system of the axon and the origin of granulated and non-granulated vesicles in regenerating nerves

Summary Electronmicroscope observations have been made on compressed sciatic nerves and preganglionic afferents to the superior cervical ganglia of rats. After 6 hours, the proximal regenerating stumps of both myelinated and unmyelinated axons become filled with enlarged neurotubules and vesicles. Granulated vesicles of 750–900 Å, having a dense core become abundant in all types of regenerating axons and they increase in number after 24 hours. The vesicular material is formed by dilatation and pinching off from neurotubules. The existence of a neurotubular system within the axon, connected with the Golgi complex at the perikaryon and involved in the formation of vesicles, is postulated. The presence of granulated vesicles in all types of regenerating axons and nerve terminals is discussed in relation with their possible functional significance. The distal stumps of compressed sciatic nerves show, after 6 hours, a considerable increase in membranous material within the axoplasm mainly represented by multivesicular and lamellar bodies. This reaction, which is interpreted as being autolytic, is compared with the regenerative reaction of the proximal stump.This paper was supported by Grants of the Consejo Nacional de Investigaciones Cientificas y Técnicas and U.S. Air Force (AF-AFOSR 963—67).