FIG. 3.

Time-lapse imaging of sprout pathfinding. (A) Representative phase contrast image of a misaligned sprout at 24 h in a matrix with collagen density=1.2 mg/mL and VEGF Profile 1. Inset shows the tip of the sprout at higher magnification. (B) Fluorescent micrograph of Cell Tracker labeled cells. After 48 h, the sprout in (A) has turned to align parallel to the VEGF gradient. (C) Schematic of sprout pathfinding image analysis: initiation (ϕ), starting elongation (θ₁), and final elongation (θ₂) angles relative to the VEGF gradient.