Spermatogonial Transplantation in Fish: Production of Trout Offspring from Salmon Parents

Many salmonid species have recently become at risk of extinction. For fish species where eggs cannot be cryopreserved, establishment of techniques to preserve genetic resources other than egg and embryo cryopreservation is imperative. In the present study, spermatogonia from male trout were transplanted into the peritoneal cavity of newly hatched sterile triploid salmon. Transplanted trout spermatogonia colonized the gonads of sterile salmon recipients. In male recipients, transplanted spermatogonia underwent spermatogenesis. Further, in female recipients, transplanted spermatogonia underwent oogenesis. At 2 years after transplantation, sterile salmon recipients only produced donor-derived trout sperm and eggs. Fertilization with the sperm and eggs obtained from the triploid salmon recipients, only the donor-derived trout offspring was successfully produced. Combined with cryopreservation of spermatogonia, the present technique would make it possible to preserve fish genetic resources and to revive extinct species when necessary.