Fig. 2. Development and transfer of a donor germline into a hybrid host. (A,B) Parental strains used for the production of interspecific medaka hybrids. (A) A Kaga female. (B) A Hainan male. (C,D) A chimeric host embryo at 1 day (four-somite stage) (C) and 3 days (D) post-fertilization showing a successful transfer of donor PGCs (arrows). The somatic contribution of the donor cells to the anterior neuroectoderm lineage is also shown (^* in C). (E) A representative matured host female with a cluster of fertilized eggs (arrow). (F-H) Confirmation of a successful germline transfer by detection of the pigmentation marker gene, b. (F) F1-hybrid; B/B. (G) Donor; b/b. (H) Progeny of a transplanted hybrid host female; b/b. The embryos shown are at 2 days post-fertilization. (I-K) Cross sections of ovaries from a 4-week-old Kaga strain (H), non-transplanted hybrid (J) and transplanted F1-hybrid host (K). The transplanted hybrid ovary contains growing oocytes (arrows in K). (L) Confirmation of germline transfer by detection of strain-specific genetic markers. Two M-markers (Kimura et al., 2004) were amplified from genomic DNAs of Kaga, Hainan, F1-hybrid, donor and the progeny of the F1-hybrid transplanted with donor PGCs. Note that the patterns of marker amplification for the progeny are identical to those of the donor. Scale bars: 200 µm.