Suprabasal cells converge and extend via cell intercalation.

<p><b>A.</b> Still from a confocal time-lapse video (<a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.1002405#pbio.1002405.s008" target="_blank">S4 Movie</a>) of a randomly GFP-labeled E12.5 tooth slice culture. <b>B,C.</b> Frames from the middle boxed region in (A) showing three individual cells rearranging themselves from an oblique to a vertical stack (see also <a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.1002405#pbio.1002405.s008" target="_blank">S4 Movie</a> inset). <b>D–I.</b> Three representative pairs of additional intercalating cells showing their initial (D,F,H) and final (E,G,I) positions at the indicated times (hours:minutes). Blue arrows between panels D–E, F–G, and H–I indicate paired stills. <b>J–Q.</b> A close-up of the left (J–M) and right (N–Q) boxed regions in panel A showing an example of a central delaminating cell (red arrowhead points at retracting basal contact (<a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.1002405#pbio.1002405.s010" target="_blank">S6 Movie</a>) and a lateral delaminating cell (marked with red asterisk) making contact (red arrowhead) with a suprabasal cell (see <a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.1002405#pbio.1002405.s010" target="_blank">S6 Movie</a> and text for details). <b>R.</b> Quantification of intercalation of cell pairs showing decrease in horizontal distance between their centroids during time-lapse period (t, shown in hours;minutes). Value below zero (yellow line) indicates a cell pair in which one cell moves right past another (corresponds to panels H,I). <i>n</i> = 8 from three separate explants.