Recipient preparation is critical for spermatogonial transplantation in the rat

Testis cell transplantation from mice or rats into recipient mouse seminife rous tubules results in donor cell-derived spermatogenesis in nearly all ho st testes. Normal spermatozoa are produced and, in the most successful mous e transplantations, the donor haplotype is transmitted to progeny of the re cipient. However, few studies have been performed in other species. In this report, we demonstrate that rat and mouse testis cells will generate donor cell-derived spermatogenesis in recipient rat seminiferous tubules. Deplet ion of endogenous spermatogenesis before donor cell transplantation was mor e difficult in rat than reported for mouse recipients. A protocol employing treatment of neonatal rats with busulfan was most effective in preparing r ecipients and allowed more than 90% of testes to be colonized by donor cell s. Transplantation of mouse testis cells into rat seminiferous tubules was most successful in recipients made cryptorchid and treated with busulfan. I n the best experiments, about 55% of rat testes were colonized by mouse cel ls. Both rat and mouse donor cell-derived spermatogenesis were improved by treatment of rat recipients with leuprolide, a gonadotropin-releasing hormo ne agonist. The studies indicated that recipient preparation for spermatogo nial stem cell transplantation was critical in the rat and differs from the mouse. However, modification of currently used techniques should allow mal e germ line stem cell transplantation in many species. (C) 1999 Harcourt Pu blishers Ltd.