Fig. 1. Early labelling of PGCs in live embryos. (A) Schematic representation of the kop promoter region fused to EGFP-F-nos1-3'UTR that was used to generate transgenic fish. (B) Whole mount in situ hybridization of progeny of transgenic females showing the distribution of egfp RNA. The inset included in the image depicting a 22 hpf embryo shows a magnification of the region where the PGCs normally reside. (C) Specific expression of EGFP-F in the zebrafish germline starting at the earliest stages following its formation. No specific EGFP-F expression prior PGC specification (e.g. 2.75 hpf) can be detected.