Figure 3.

Quantitative analyses of ephrin-dependent axonal growth, branching, and degeneration. Neurons were cocultured with ligand-expressing or control cells for 24, 48, and 96 hr and then fixed and stained with anti-tau antibody. Eight to 10 randomly selected neurons were quantitated for each parameter. (a) Total length of each axon. The measurements include both unfragmented and fragmented stretches of axons and are the sum of the length of axons and all branches. The total axonal length increased over time, primarily because of the increase in the number of branches. (b) Length of the region of each axon without fragmentation. Axonal fragmentation usually starts at the growth cones and progresses toward the cell somas. The segments of axons closest to the somas and without fragmentation were measured. (c) Number of total branches of each axon. (d) Number of branches without fragmentation. Data analyzed with two-factor ANOVA (substrate condition and time in culture). Bars = SEM. ∗, +, and #, Significant differences compared with the control, 24-hr, or 48-hr time points, respectively (P < 0.05; Scheffe’s test).