Fig. 2. Ectopic anterior PGCs migrate posteriorly towards the main clustering position in spt mutant embryos. (A-J) Fluorescent pictures of embryos injected with GFP-nos1-3'UTR. Dorsal views, anterior is upwards. (A) In wild-type embryos, most PGCs are located in two medial-to-lateral lines at the head-trunk border at the one-somite stage. (B-J) Time-lapse cinematography of a spt mutant embryo starting at early somitogenesis. During the 3.5 hours shown, the embryo was kept at 25°C, thus it developed to approximately the six-somite stage. On each side of the embryo, a pair of PGCs that were initially located close to each other in ectopic anterior regions is marked by arrowheads and arrows. Note that two of these cells end up in the ectopic anterior cluster (arrowheads), while the others migrate over a considerable distance posteriorly towards the main clustering position (arrows).
