Fig 1: Detection of germ line markers in cells migrating through the dorsal mesentery and colonizing the genital ridge. (A) OCT4- and (B) VASA-expressing migratory-PGCs in the developing hindgut endoderm in embryos with 8–12 pairs of somites; (C) FRAGILIS, (D) STELLA, (E) SOX2 and (F) SOX17 were not detectable at this stage. (G) OCT4-, (H) VASA- and (J) STELLA-expressing migratory-PGCs in the mesentery in embryos with 25–30 pairs of somites; red arrows indicate mitotic dividing migratory-PGCs (I) FRAGILIS, (K) SOX2 and (L) SOX17 were not detected at this stage. (M) OCT4, (N) VASA, (O) FRAGILIS and (P) STELLA positive migratory-PGCs in the mesentery in embryos with 35–40 pairs of somites; (Q) SOX2 and (R) SOX17 were not detected at this stage. (S) OCT4-, (T) VASA-, (U) FRAGILIS-, (V) STELLA- and (X) SOX17-positive migratory-PGCs colonizing the genital ridge in embryos with >50 pairs of somites; (W) SOX2 was not detected at this stage. HE column: general view of embryo sagittal sections showing the area detailed in the corresponding lines (blue dotted circles). Green arrows indicate immune-positive cells. Scale bar: 20 µm (HE column); 40 µm (A–C,E,F,K–Q,S); 1,000 µm (D,G–J,R,T–X).