TRANSPLANTATION OF TESTIS GERMINAL CELLS INTO MOUSE SEMINIFEROUS TUBULES

In the adult male, germ cell differentiation takes place in the semini ferous tubules of the testis by a complex, highly organized and very e fficient process. A population of diploid stem-cell spermatogonia that lie on the basement membrane of the tubule continuously undergoes sel f-renewal and produces progeny cells, which initiate the process of ce llular differentiation to generate mature spermatozoa. Each testis con tains many seminiferous tubules, which are connected at both ends to a collecting system called the rete testis. The mature spermatozoa pass from the tubules into the rete and are then carried through efferent ducts to the epididymis for final maturation before they are ready to fertilize an egg. In previous studies, we have demonstrated that donor testis cells collected from a fertile mouse are able to generate sper matogenesis when transplanted to the seminiferous tubules of an infert ile male. The spermatozoa produced by the recipient from the donor-der ived spermatogonial stem cells are able to fertilize eggs and produce progeny carrying the donor male haplotype, Furthermore, donor testis s tem cells from a rat will generate normal rat spermatozoa following tr ansplantation to a mouse testis. The spermatogonial transplantation te chnique is clearly valuable and applicable to many species, but it is difficult, Therefore, several procedures to introduce donor cells into the seminiferous tubules of a recipient have been developed using the mouse as a model, and they are described here in detail. The results indicate that microinjection of cell suspensions into the seminiferous tubules, efferent ducts or rete testis are equally effective in gener ating donor cell-derived spermatogenesis in recipients, Each approach is likely to be useful for different experimental purposes in a variet y of species.