Irradiated Mouse Testes Efficiently Support Donor Spermatogenesis from Mice and Rats

Testicular cell transplantation has been widely used to investigate the biology of spermatogonial stem cells, production of transgenic animals, and restoration of fertility in rodent models. One critical step in successful transplantation is the preparation of the recipient testes. Busulfan has been widely used, but irradiation has been often suggested as an alternative. There have only been limited reports of the use of irradiated animals as recipients for studying differentiation of transplanted cells and there has been no direct comparison of irradiation and busulfan as preparation methods. Mouse testes, given local 1.5 + 12-Gy fractioned irradiation, were compared to busulfan-treated testes as recipients using mouse-to-mouse and rat-to-mouse germ cell transplantation. The fractioned irradiation schedule resulted in depletion of endogenous spermatogenesis similar to that produced by busulfan doses of 50-55 mg/kg. When immature mouse or rat testicular germ cells were transplanted into the irradiated testes, donor cells derived from either rat or mouse spermatogonial stem cells were able to form colonies of differentiated spermatogenic cells 10-13 weeks after transplantation with similar efficiencies as in busulfantreated testes. Locally irradiated testes could be considered as an alternative to busulfan for recipients of germ cell transplantation in animals that cannot endure the systemic toxicity of busulfan. 5