Analysis of THN migratory movements. (A) Kymograph of a portion of Video 6 (229–390 min) showing the gradual movement of cell nuclei toward the MHB. Images have been rotated 45° and only the blue channel is shown in order to better visualize the nuclei. Each nucleus is labeled with a colored dot. Time between frames is 404.2 s. (B) Kymograph created from Video 8, showing two saltatory movements of the nucleus (asterisks) and the comparatively smooth forward migration of the centrosome during ventral migration. Images were rotated 45° and the time between frames is 522.6 s. The centrosome is ahead of the nucleus immediately before a nucleokinetic movement, but is overtaken when the nucleus jumps forward. (C) Graph of the cumulative migration distance (in any direction) for each nucleus in Video 6. Colors match the dots used for labeling nuclei in A. Tracking was done on 2D maximum projections with the Manual Tracking tool of ImageJ. The nuclei move at a gradual pace until they reach the MHB, at which point one nucleus undergoes a saltatory movement (red bar). The blue bar represents the region of the video shown in the kymograph in A. (D) Graph of the cumulative migration distance (in all directions) of the centrosome and nucleus in Video 8. During ventral migration, the cells undergo obvious nucleokinetic movements (red bars). The centrosome moves at a more consistent and gradual pace. (E) Pie chart showing the amount of time that the centrosome spends ahead of, lateral to, or behind the centroid of the nucleus (n = 4 cells, 3 embryos). (F) 3D graph showing the portion of time during which the centrosome and nucleus in Video 8 are each stationary, move in the direction of migration (forward), or move opposite to the direction of migration (backward). The movement of both organelles is predominantly in the direction of migration, but much of the forward centrosomal movement occurs while the nucleus is stationary.