Appendix A.2 Single cell seeking behaviour at spheroid leading edge

Time-lapse animation of bright-field images show invasion of WK1 spheroids into undiluted Matrigel™ matrix over 72 hours. Single cells at the leading edge of the invading spheroid exhibit cyclical "seeking" behaviour, detaching from collective front, then reattaching to "pull" remaining cell forward. Animated gif is 20 frames per second, time interval between frames is 20 minutes. Scale bar indicates 200µm.明场图像的延时动画展示了WK1细胞球在72小时内侵入未稀释的Matrigel™（基质胶）基质的全过程。侵入性细胞球前沿的单个细胞表现出周期性的「探寻」行为：从细胞集体前沿脱离，随后重新附着以「牵拉」剩余细胞向前移动。该动态GIF的帧率为每秒20帧，帧间时间间隔为20分钟。标尺（scale bar）标注的长度为200微米。