Snapshot images of 3D time-lapse videos of developing hair follicles from eGFP-Col4a2; mem-tdTomato mice. (A and B) Snapshot single z-plane images of cells and BMs tracking at 30-min intervals from 0 to 9 h 30 min. Cells and the BMs in the lower (A) and upper stalk regions (B) were tracked. The BM was re-photobleached several times to maintain a clear photobleached edge. The lower photobleached edge of the BM (indicated by white arrowheads) and epithelial basal progenitors initially located at this photobleached edge (indicated by yellow dots) were tracked. A white dot marks the other daughter cell following the division of the cell marked with a yellow dot. Scale bar: 20 μm.