Spermatogonial transplantation, developed in
the past decade by Brinster and colleagues, is a
fascinating and powerful technique utilized to
investigate male reproductive biology, mainly the
aspects related to spermatogenesis and the stem cell
biology. This technique also offers tremendous potential
for studies involving biotechnology, transgenic animals,
and the preservation of the genetic stock of valuable
animals or endangered species. Although germ cell
transplantation is well characterized for mammals, there
is no study utilizing this approach for fish. Due to its
fast growth, relative small size when it reaches sexual
maturity, good adaptability to different environmental
conditions and economical importance, the tilapia
(Oreochromis niloticus) is an excellent experimental
model. In the present study, we investigated the viability
of adult tilapias as a recipient model for germ cells
transplantation in fish. For this purpose, all approaches
utilized in the present study for spermatogonial
transplantation, such as endogenous spermatogenesis
depletion, obtention, selection and spermatonia labeling,
and the transplantation through the common urogenital
papilla, were standardized in our laboratory. The
preliminary results found for the recipient tilapia testes,
evaluated by light and fluorescence microscopy, showed
the presence of PKH26 labeled germ cells cysts in the
seminiferous tubules. These findings obtained, for the
first time in fish, suggest that spermatogonial germ cells
can be successfully transplanted directly into the testis
of this teleost. Therefore, tilapias might be utilized as an
experimental model to investigate the germ cell biology
and the testis function in teleosts. Moreover, this
technique could be also utilized as a potential approach
for fish bioengineering, preservation of genetic stock of
endangered fish species or fish strains carrying
commercially valuable traits.