Fig. 1

vasa is required for PGC migration. MOvas was zygotically injected at 1.5 ng per NgVg transgenic embryo. Embryogenesis was regularly monitored and PGCs (green) were visualized by fluorescent microscopy. Three phenotype classes are shown at critical stages at 19, 22 and 34. (A–C′) Control morpholino MOvc-injected embryos showing normal development. A similar number of PGCs is seen in control and vasa-depleted embryos. An ectopic PGC is indicated by an arrow in (C). (D–F′) Class I morphant. Gastrulation and somatic development are normal as evidenced by major organ systems including somites (so), eye, ear and pigment cells (pc) that are black in the eye and yellow autofluorescent in the trunk. Specifically, defects in PGCs are clearly seen. By stage 22 when PGCs are normally in two bilaterally aligned clusters dorsal to the somites (B and B′) PGCs in all of MOvas-depleted embryos also form two bilateral clusters but exhibit slightly wider distribution relative to the embryonic axis (broken line) (E and E′). Subsequently, when PGCs are normally seen in the gonad (gd), many PGCs distributes to ectopic sites outside the gonad (F and F′). (G–I′) Class II morphant. Gastrulation with slight defects leads to a smaller axis with visible somites (H). Bilateral distribution is maintained at stage 22 but further widened (H′). At stage 34, the majority of PGCs reside in ectopic sites (I and I′). This class forms major organs and often exhibits the accumulation of blood cells (bc, red). (J–L′) Class III morphant. Gastrulation is arrested at 50% epiboly (J). PGCs are seen in disorganized cell mass that do not form the axis and organs. Red fluorescent micrographs show relative doses by a co-injected tracing dye (A, D, G and J). (M–P) Dorsal views of a MOvas-injected whole embryo at stage 34 showing somatic development and PGC distribution. (M and N) Focus on the head. (O and P) Focus on the trunk and PGCs. Bright field micrographs show gross morphology (B–C, E–F, H–I, K, M and O). Fluorescent optics shows GFP-positive PGCs (B′–L′, N and P). (Q) Phenotype classes. Coinjection of vasa RNA increases class I and decreases class II and III embryos. (R–T) PGC development. (R) PGC number at stage 22. MOvas with increasing doses slightly decreases the PGC number. The differences are not statistically significant. (S) Number of embryos with at least four ectopic PGCs. (T) Number of ectopic PGCs per embryos. Co-injected vasa RNA counteracts the effect of MOvas on PGCs. Numericals in or above columns indicate total numbers of embryos (Q–S) and PGCs (T) examined. Data are in means ± SD (error bars). ^∗p < 0.05; ^∗∗p < 0.01.