Figure 2.

Flux during towed growth in vivo when adhesions are absent. Transport profiles are shown at 0 (A), 1 (B), and 5 (C) days of elongation. The rate of axonal elongation is set to $\alpha =$9.24 μm h⁻¹. Dimensionless values characterizing the rate of axonal elongation (A = 1.98) and the rate of mass addition along the axon (C = 1.00) are based on experimental data shown in Table 1. Solid lines denote the flux profile necessary to fulfill protein demand (Eq. 6). The position along the x axis where the stretch-transport (Eq. 7) and other-transport lines intersect is $x_{1/2}/L$. Stretching accounts for more than half of the anterograde transport in the region: $x_{1/2}/L<x\le 1$. As the axon elongates, this value increases toward 1. The size of the region is significant in the absence of adhesions.