DEV01862 Supplementary Material

Files in this Data Supplement:

• Movie 1 -

  Movie 1. Cell behavior during mhb formation. A spinning disc confocal time-lapse, showing the developing mhb region of a living zebrafish embryo that contains GFP-expressing cells. Shown is a dorsal view, anterior is towards the left. The movie starts at about the 10-somite stage and follows mhb development up to about 30 hours post fertilization. Elapsed time is indicated in hours. Red dots indicate future midbrain cells, yellow dots indicate future hindbrain cell, black arrowheads indicate the boundary. During the movie, the formation of the third ventricle is indicated by white dots. Broken black lines mark the mhb indentation at later stages. Two cell populations on either side of the mhb become separated by a gap of unlabeled cells. No mixing between the cell populations can be observed.

• Movie 2 -

  Movie 2. Data assembled from time-lapse three (Table 1), starting at the 10-somite stage and ending at the 24-somite stage. A stripe of nuclei directly at the boundary is marked by red (future Otx-positive) and yellow (future Otx-negative) dots. The nuclei are then followed throughout the whole sequence. Because the movie shows only one focal plane of the time-lapse, several nuclei move out (and sometimes back into) the focal plane. Nevertheless, the position of these nuclei was recorded throughout the whole time-lapse At the end of the movie, these nuclei are marked by translucent dots in their correct xy position. During embryonic development, initially neighboring nuclei become separated and move several cell rows away from each other. Despite this movement, nuclei remain within their respective groups and are separated by a clear boundary (gray line at the end of the movie). Many cells can be seen to divide at the midline. Two of these cells are marked by an arrow before and by arrowheads after division. The first division gives rise to daughter cells in both halves of the neural tube, the second division is oriented in an AP direction. Here, right after division, one daughter cell is located slightly within the Otx-positive domain, but reintegrates into the Otx-negative cell population. Gray broken lines mark the outline of the neural plate.