Movie 2

The IK remains an integral part of the growing tooth bud as shown in Fucci cell cycle reporter E12.0+12 h molars by confocal live tissue imaging
Fluorescence confocal microscopy time-lapse of a Fucci cell cycle indicator E12.0 whole-mount mandible explant imaged for 12h. Image stacks were taken at 20min intervals, and the playback speed here is five frames per second. The tracking of individual cell fates during the early bud invagination, is shown as a surface rendering: G1/G0 phase cells are shown in red hues and S/G2/M cells in green. Individual cell divisions of mother cells and their daughters are color coded in blue, green and yellow shades, respectively. IK cells remained in G1/G0 phase and remained an integral part of the growing tooth. S/G2/M phase cells and cell divisions in both basal and suprabasal populations contributed to invagination and growth throughout the bud.

The initiation knot is a signaling center required for molar tooth development

Isabel Mogollón, Jacqueline E. Moustakas-Verho, Minna Niittykoski, and Laura Ahtiainen

Development 2021. 148:None-None; doi: 10.1242/dev.194597