Effects of Disruption of Microtubules on Translocation of Particles and Morphology in Tissue Cultured Neurites

The role of microtubules in axoplasmic transport was studied by using colchicine and vinblastine in tissue cultured dorsal root ganglion cells dissected from chick embryos. After 3-4 days in culture, the effects of the agents on particle movement were examined under Nomarski optics. The movements of the particles were analyzed with high-contrast video systems. The number of transported particles passing through one region decreased after exposure to colchicine or vinblastine in concentrations greater than 1 X 10(-7) M, but these agents did not affect the velocity of the transported particles. After treatment with the agents swelling occurred in regions where particles sometimes stopped or slowed down in normal conditions. The intervals between swollen regions were 5-25 micron and transported particles finally stopped in the swollen regions. After 1 h of treatment with 1 X 10(-5) M colchicine, electron micrographs showed many organelles but no microtubules in the swollen regions. It is thought from these results that the disruption of microtubules in neurites might occur at the ends of the microtubules, followed by swellings in the neurites and particle transport blockade, but the morphological change itself might not have an effect on the transport of particles.