Axoplasmic Streaming and Proteins in the Retino-Tectal Neurons of the Pigeon

Time course studies based on the biochemical and autoradiographic detections of labelled proteins after intraocular injection of tritiated leucine have been made to analyse the origin and the fate of newly synthesized macromolecules in the retino-tectal neurons of the pigeon. Some of them migrated intra-axonally at a rate of 20–500 mm/day, and seemed to be largely destined to renew some synaptic materials, possible some components of vesicles and mitochondria. The largest portion of the migrating proteins moved at a rate of about 1 mm/day, and was found mainly in the soluble and microsomal fractions. It was probably destined to renew some elements of the axon; however it reached also the terminals. Some data suggested that the rapid phase of axoplasmic flow might be subdivided.