Axonal delivery of neuroplasmic components to muscle cells.

Substances labeled with phosphate-32 and carbon-14 and applied to hypoglossal nuclei in rabbits traveled down the hypoglossal nerves and after several days began entering only the muscle cells of the tongue. Prevention of axonal delivery on one side caused unilateral labeling of the tongue. Labeled substances delivered by extracellular fluids labeled all cells indiscriminately. The axonal conveyance of neuroplasmic components to peripheral cells may provide a basis for trophic influences of neurons on other cells.