Video 6. PGCs extend filopodia towards the chemokine source, prior to their morphological polarization and directed migration towards cells producing the attractant.
Cells from 4 hpf medNY054 homozygous embryos, in which Cxcr7b expression was inhibited and which express mCherry-F' (red) and either control RNA (part control transplant) or express cxcl12a RNA (part Cxcl12a transplant) were transplanted into 6 hpf host medNY054 homozygous embryos. The PGCs in the host embryos were labelled with EGFP-F' and their reaction to the transplant was monitored on a Zeiss AxioImager.M1 microscope equipped with a dual view filter (MAG Biosystems), Photometrics camera (Cascade II) and VS-Laser Control. Acquisition of the 28 min time-lapse video started immediately following the transplantation using a 40× objective. Z-stacks were captured with 24 planes per time point, at focal planes 4 µm apart, 15 s interval, 300 ms exposure time with binning one. Green arrowheads mark the position of filopodia, red asterisks mark the position of the golgi, blue dots indicate no migration and blue arrows indicate morphological PGC polarization and movement. Time in minutes and scale bar represents 10 µm.