EXPERIMENTAL STUDY ON INTRATESTICULAR ALLO-IMPLANTATION OF TESTIS TISSUE

Abstract

Intratesticular allo-implantation of testis tissue of either rats or nude mice was carried out with various combination of ages between donors and recipients. Some of the recipients were administered either immunosuppressants or hCG after the implantation. The viability and spermatogenic function of the grafted tissue were evaluated independently according to the criteria defined on the basis of findings pbtained in the present experiments.
The order of the viable rate of implanted tissues was as follows; between nude mice, between immature rats, and then from immature to mature rats. In the last group, the younger the donor, the better the viable rate. In contrast, no grafted tissues were viable when they were implanted from the mature to another mature rat. The viable rate of tissues grafted from immature to mature rats was improved by administration of immunosuppressants (azathioprine and/or prednisolone) except for the group administered azathioprine alone. No marked changes were observed in the viable rate of grafted tissues between mature rats after administration of hCG to the recipient, which should increase intratesticular concentration of testosterone.
Inhibition and delayed induction of spermatogenesis were observed in the grafts implanted into nude mouse testes. The younger donor resulted in the better induction of spermatogenesis in the grafted tissues of rats. The induced spermatogenesis, however, was impaired in the grafts survived for 182 dyas when compared with those which survived for either 70 or 77 days. Grafted immature testis tissues in immature rat recipients showed promoted induction of spermatogenesis in comparison with that of intact testes at the equivalent age. Administration of immunosuppressants revealed an inhibition of spermatogenesis of testis grafts.
The above results indicate that ageing of grafted tissues including decreased viability against ischernia and manifestation of antigenicity with maturation of germ cells is an important factor affecting their acceptance and spermatogenesis. Endocrine milieu in testes of the recipient was also found to influence the spermatogenic induction in the accepted grafts.