Figure 2. 4T1 breast cancer spheroids cause long distance radial orientation of surrounding collagen.

(a) DIC (top) and reflection microscopy (middle) images of collagen-embedded spheroid 48 hours post injection and corresponding collagen orientation detection (bottom; red, radially oriented collagen fibers; blue, tangential collagen fibers). Dashed lines note the indicated distances from tumor spheroid border. Note the dense red at distance 0–1 mm with gradually increasing randomness of colors at increasing distances. In i and ii zoom-ins of the indicated areas are shown. (b) Collagen orientation parameter calculated 48 hours after injection at the indicated distances from individual tumor spheroid borders for 29 4T1 injections (black circles) and 22 wells lacking tumor spheroids (gray squares) from 5 independent experimental replicas with standard deviations. The fit equation (black line) is shown.