Fig. 4.

Delaminating NBs directionally migrate towards a common coalescence region. (A) Two tracks (white lines) of delaminated NBs from lateral domains of the otic neurogenic region. (B) Two tracks (white lines) of delaminated NBs from medioventral domains of the otic neurogenic region. The otic vesicle contour is delineated with a white dashed line. See also Fig. S8 and associated Movies 9 and 10. (C) Summary tracks using DiPER normalized to the origin and directionality rose plots (cyan for lateral and green for medioventral) of delaminating NBs (Breau et al., 2017; Gorelik and Gautreau, 2014) showing that migration of NBs is directed. Ticks in axes represent 10 µm increases. (D) Graphs of quantified data of NB migratory properties. Black arrowheads depict maximum velocities. Individual data shown in dark orange dots. Horizontal line is the median. Light orange shadows represent the s.d. For a separate analysis of lateral and medial delaminating cells, see Fig. S8. (E) Top panels show an otic delaminating NB (outlined in white) migrating towards the aLL. Lower panels show an NB (outlined in white) migrating towards the SAG. (F) Tracking several NBs in the same embryo shows aggregation towards a common region (asterisk) irrespective of NB origin inside the otic neuroepithelia. White arrowhead indicates an otic NB attracted to the aLL. (G) Graphic summary of migratory paths undertaken by NBs. Lateral NB shown in blue, medial NB shown in green. Dotted lines represent the migratory paths. Black dotted line shows aLL NB migrating to the SAG. (H) Qualitative examples of non-collective and collective migration. Otic epithelium encircled with dashed line. Migrating NBs outlined with white line. (I) Plotting several cases summing the distance of one NB with respect to its neighbours across times shows a negative overall regression, which is indicative of distance shortening between cells, thus indicating aggregation. Otic vesicles are depicted inside white dashed lines. Images in A and H are from the same raw data as Movies 9 and 11, but with different contrast enhancements to the images to show tracking of individual or contiguous cells. Anterior is always to the left and posterior to the right. aLL, anterior Lateral Line. Scale bars: 20 µm.