MALE GERM-CELL TRANSPLANTATION - PRESENT ACHIEVEMENTS AND FUTURE-PROSPECTS

Germ cells are unique, since their surviving descendants can undergo m eiosis and differentiate into gametes, which transmit genetic material from one generation to another. We now know that male germ cells, whe ther they be primordial germ cells in gonadal ridges, gonocytes, or st em spermatogonia, are transplantable. The donor cells can be transferr ed by direct microinjection into the seminiferous tubules, rete testis or efferent ducts, depending on the recipient species. Following tran splantation, the donor cells undergo spermatogenesis in the host's sem iniferous tubules in rats and mice, and have even sired offspring in m ice. Interspecific germ cell transfer is possible if the recipient's i mmune system is defective; nude or SCID mice can even produce rat sper matozoa. However, the major obstacle restricting widespread use of thi s new technology is its extremely low success rate. This article discu sses some ideas for improving the success rate of the transfer techniq ue, and considers several potential applications.