Germ Cell Transplantation: A Potential Tool for Propagation of Endangered Fishes

Germ cell transplantation, a powerful assisted reproductive technology, is widely used to study the functional characterization of stem cells. The technology is also used for conservation and propagation of elite germlines. In teleost fish model, the technique has been successfully established to generate donor-derived gametes by transplanting primordial germ cells (PGC) or spermatogonial cells at various developmental stages such as embryonic, hatchling and adult stage. Various studies have confirmed, irrespective of developmental stages and methods of transplantation, the recipient fish have produced the surrogate gametes. The most potential application of this technique are 1) propagation of endangered and commercially important fish species those are difficult to breed in confinement, 2) control of invasive fish species, those pose threats to the native species and, 3) production of transgenic individual by transfecting the donor spermatogonial cells before transplantation. Very recently, the technique is also used to provide stem cell therapy to senile fishes those have lost their reproductive competence because of old age. The germ cell transplantation technique appears to be most valuable at the moment as other assisted reproductive technologies such as cryopreservation and in vitro gametogenesis fails to conserve or propagate the female gametes.