Competition for tubulin between growing neurites during development

Abstract At its tip—called growth cone—a neurite is elongated by the assembly of tubulin into microtubules. We present a model of elongation (extended from Van Veen and Van Pelt, Bull. Math. Biol. 56 (1994) 249–273) in which tubulin is produced in the soma and transported to the growth cone by diffusion and active transport. The model accounts for competition observed between growing neurites of the same neuron and for ‘dormant growth cones’, and shows that cessation of growth in one neurite—e.g., when it encounters a target—can trigger the growth of the other neurites. The model makes testable predictions for the time course of outgrowth and the concentration of tubulin during competition.