ABSTRACT
Animals generated by transplantation of homospecifi c Primordial Germ Cells (PGCs) or Spermatogonial Germ Cells (SGCs) are called allogenics and those by the transplantation to surrogate heterologous species are called xenogenics. During the 1990s allo-androgenic technique was employed to conserve fi sh species; progenies of the desired species were generated using a relatively simple technique involving preserved sperm and genomeinactivated (by UV-irradiation) eggs of a compatible surrogate species (Pandian and Kirankumar, 2003). From the beginning of this millennium, Primordial Germ Cells (PGCs) and Spermatogonial Stem Cells (SSCs) have been successfully used to generate allogenics and xenogenics. Some publications in this area have shown that sexual bipotency is retained by the PGCs (e.g. Takeuchi et al., 2003; Yamaha et al., 2003) and SSCs (Okutsu et al., 2006b, 2007), especially the SSCs retain the bisexual potency even after males have attained sexual maturity. The presence of PGCs has been observed from differentiated ovaries, testes and ovotestes of Liza auratus, Serranus hepatus, Coris julis (Brusle, 1988) and Xiphophrus sp (Flores and Burns, 1993); however, it is not known whether these fi shes have retained the bisexual potency even after sexual maturity. In view of its revolutionary importance to sex determination, aquaculture and conservation of fi shes, information on this frontier area of research on allogenics and xenogenics is rather elaborately described.
