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Fig. 1
Quantitative live imaging analysis of cell movements during OP morphogenesis. Live imaging of OP morphogenesis was performed between the 12 somites (12 s) and 24 s stages. a, b Schematic views of the head regions of 12 s a and 24 s b embryos. For each stage, the right panel shows a lateral view (orientation of the microscope objective indicated with a grey arrow). The left panel represents the optical section indicated by double arrows in lateral views. b brain, is isthmus, mb midbrain, oc optic cup, op olfactory placode, t telencephalon. c Live imaging on a ngn1:gfp embryo between 12 and 24 s, showing the progressive coalescence of the two elongated GFP+ OP domains into compact and spherical clusters on each side of the brain (XY dorsal view of the head, maximum projection of a 92 µm Z-stack). Asterisks indicate GFP expression in the brain. d YZ sections corresponding to the images shown in c, with H2B-RFP-labelled nuclei (magenta), showing the shape of the brain and placode tissues along the DV axis. Scale bars: 50 µm. e Tracks of anterior, central and posterior placodal cells (as defined in Supplementary Fig. 4b), merged at their origin, and associated directions of movement (as defined in Supplementary Fig. 4c). All cells were tracked throughout the morphogenesis process, during a 500 min period of time. f Representative tracks of placodal cells from three different AP positions (magenta), overlying skin cells (green) and adjacent brain cells (blue). Skin cells are located above the brain and the placode. Dots represent initial positions. The dotted grey line indicates the brain surface at 12 s. Cells from placode extremities move parallel to the brain surface to converge towards the centre of the placode (convergence movements along the AP axis, full arrows), then move laterally, away from the brain (lateral movements along the ML axis, dotted arrows). Central cells undergo lateral movements only. g MSD plot and its log equivalent for placode, skin and brain cell trajectories. α is the slope of the log plot and is used an indicator of directional (>1) vs. diffusive (=1) movement