Figure 1. 4T1 breast cancer spheroid expansion and collagen network organization.

(a,b) 4T1 tumor spheroid at the day of injection (a) and 48 hours after injection (b). (c) Spheroid mask covering core spheroid and migrating cells at 48 hours, which was used as boundary for collagen organization calculations (red dashed circle). (d) Inverted reflection microscopy image with tumor border (red dashed circle) showing radial orientation of surrounding collagen.