Changes in the rate of axonal flow of proteins through the branches of motor and sensory neurocytes during the period of intense growth of the sciatic nerve in rats

14C-glycin was microinjected into the ventral horns of the spinal cord or spinal ganglions. The rate of fast and slow axoplasmic transport of proteins in the axons of motor and sensory neurons was studied by liquid scintillation. Motor fibers of the sciatic nerve manifested a marked decrease (P less than 0.05) in the rate of slow axoplasmatic transport of the labeled protein from 5.25 +/- 0,31 in 2-week-old rats to 3.45 +/- +/- 0.23 mm/day in 4-week-old animals and a significant increase in the rate of fast axoplasmic transport (P less than 0.05) from 99 +/- 13.2 (2-week-old rats) up to 198 +/- 18.9 mm/day (in 4-week-old rats). The two-week-old rats had higher rates (4.5 +/- 0.3 mm/day) of slow axoplasmic transport of the labeled protein in the central and peripheral axons of sensory neurocytes and lower rates of fast axoplasmic transport (126 +/- 14.7 mm/day) as compared with 4-week-old animals (3.75--4.1 +/- 0.25 -- slow transport; 144 +/- 23.34 mm/day -- fast transport). However, the differences described are not significant.