THE EXTENT OF AXOPLASMIC TRANSPORT DURING DEVELOPMENT, DETERMINED BY MIGRATION OF VARIOUS RADIOACTIVELY-LABELLED MATERIALS

Abstract— Several isotopic precursors have been monocularly injected into chick embryos and into day-old or 15-day-old chicks. After various intervals, the incorporation of various isotopes into acid insoluble material within the retina of the injected eye and within the optic lobes, was determined. Radioactive proline and fucose were used as precursors of protein and glycoprotein respectively while uridine was used as an RNA precursor. The proportion of rapidly migrating proteins and glycoproteins was reduced during maturation. The extent of RNA migrating also appeared to decline during development. The proportion of synthesized protein that was transported was relatively constant and independent of the amino acid used. Around 30 per cent of retinally synthesized glycoprotein migrated distally and this migrating material appeared to contain very few sialic acid residues. A considerable amount of retinally synthesized gangliosides also appeared rapidly in the distal regions of the optic nerve.