Hypothetical roles of viscosity in axonal elongation. A. Microtubules with docked mitochondria are shown interacting through cross linkers. B. The presence of additional or different types of cross-linkers could increase axonal viscosity in adult axons. C. Microtubule polymerization coupled with microtubule sliding. D. A reduction in the concentration of tubulin could limit axonal growth. E. The relative absence of neurofilament polymers in embryonic axons could reduce axonal viscosity as compared to F. adult axons.
Lamoureux et al. BMC Neuroscience 2010 11:140 doi:10.1186/1471-2202-11-140