Since most of the POU5F1 expressing gonocytes/spermatogonia showed affinity for lectin-DBA, the testes of the recipient mice were examined for the presence of buffalo gonocytes/spermatogonia using DBA staining. Lectin DBA is a specific marker of buffalo spermatogonia and shows no affinity for mouse testicular cells. Using testis transplantation assay, we found that gonocytes/spermatogonia from the testis of prepubertal buffalo could colonize recipient testes. One month after transplantation, DBA-positive germ cells were detected in the testes of the recipient mice located in the area of the seminiferous tubule, consistent with the stem cell niche. The buffalo gonocytes/spermatogonia could not only colonize the recipient mice testis but also showed lateral expansion in the seminiferous tubules of mice. The chain of cells connected by intercellular bridges represents proliferating germ cells in the testes of the xenotransplanted recipient mice. In the present study, enrichment of gonocyte/ spermatogonia population was not done. This explains the small number of seminiferous tubules colonized with buffalo gonocytes/ spermatogonia in xenotransplanted mice testis. Proliferation and differentiation of xenogenic germ cells depends on the microenvironment of the seminiferous tubule and interactions between germ cells and somatic cells. It is likely that the microenvironment in the mice testis supports proliferation of buffalo gonocyte/spermatogonia. Similarly, spermatogonia from large domestic animals such as boars, bulls, and stallions in the prepubertal stage, have shown colonization and proliferative ability in recipient mice testis. In the transplanted testis, occasionally, a few DBA-positive cells were present in the lumen of seminiferous tubules. This raises the possibility that not all gonocytes/spermatogonia were able to migrate to the basement membrane of the seminiferous tubule, the area consistent with the stem cell niche, to colonize the recipient testis due to lack of stem cell potential. This is in agreement with the finding in the present study where a few DBA-positive cells showed weak or no POU5F1 expression in double immunoflouroscence analysis of isolated testicular cells from prepubertal buffaloes. These findings suggest that non-colonized DBA-positive cells represent gonocytes/ spermatogonia that have weak or no expression of POU5F1. This, however, could not be confirmed in xenotransplanted testis as mice spermatogonia express Pou5f1. Alternatively, early collection of recipient testis may not have given sufficient time for gonocyte/spermatogonia to colonize the recipient testis.