Axoplasmic transport in the crayfish nerve cord.

Axoplasmic proteins in the crayfish nerve cord were labeled by the incorporation of high specific activity (3)H-leucine that was injected into one of the abdominal ganglia. The labeled proteins moved caudad as a sharply defined peak at 1.1 mm/day. The level of radioactivity in the cord decreased slowly as the peak approached the tail. From the sharpness of the peak and the low decrement of label with distance it is deduced that the axoplasm is probably a gel, and some of it is not consumed as it is transported along the axon but reaches the terminal and, perhaps, the synaptic regions.