Spermatogenesis and steroidogenesis in mouse, hamster and monkey testicular tissue after cryopreservation and heterotopic grafting to castrated hosts.

Retrieval, extracorporal storage and autotransplantation of testicular tissue could become an important strategy for preserving male gonadal function. The present study used syngeneic and immunodeficient nude mice as hosts, and immature and adult mice, neonatal and adult photoregressed Djungarian hamsters and neonatal marmosets to identify the potential of testicular tissue grafting to maintain the morphological and functional integrity of the testis. Testicular tissue was grafted s.c. either as fresh tissue or after cryopreservation into adult, orchidectomized hosts. The mice that received rodent testis tissue were autopsied 50 days later, and blood samples were collected. Sixty-five per cent of mouse isografts contained morphologically normal testicular tissue and seminiferous tubules with some degree of spermatogenic recovery. Mature spermatozoa were recovered after enzymatic disaggregation. Although the recovery of spermatogenesis was limited in adult mouse and hamster tissue, complete spermatogenesis was observed in grafts from immature rodents. Testicular tissue from neonatal marmosets developed up to the stage of spermatocytes at day 135 after xenografting. Androgen concentrations were comparable in intact control mice and in mice receiving fresh mouse and hamster grafts, slightly lower in mice receiving cryopreserved grafts and adult photoregressed hamster tissue, and low in castrated control mice and in mice receiving marmoset tissue. These results show that isografts and xenografts of immature and adult testicular tissue become functionally active as a s.c. graft in the mouse and that this approach might be useful in combination with cryopreservation as a tool for storage and activation of the male germ line and androgen replacement therapy in patients.