Transplantation of stem cells into the testis of recipient males leads to establishment of donor-derived spermatogenesis.This system provides a model for the study of spermatogenesis, manipulation of stem cell sources and evaluation of their potential capability to evolve into a germinal line. The aim of this study was to develop a surgical technique for cell transplantation into ram testis;to test a method to deplete endogenous germ cells;to inject Mesenchimal Stem Cells(MSC)into ram testis and test their capability to diffuse and colonise the epithelium of seminiferous tubules. In Exp.1, Mitotracker green was injected into the extra-testicular rete testis of 5 Sarda rams and the diffusion of the dye into the testes was evaluated.InExp.2, 10 Sarda lambs were divided into 2 groups; group1(n=5) was injected with anti-GnRH Vaccine and group2 (n=5) was the control. InExp.3: MSC were injected into the testis of 2 rams.The animals were then castrated after 7(n=1)and 21(n=1)days after injection and the diffusion and potential colonisation of MSC was histologically evaluated. The results showed that the surgical access to seminiferous tubules into the extra-testicular rete didn’t cause testicular damage and the animals resumed normal sexual activity.The anti-GnRH vaccine inhibited the production of testosterone and reversibly depleted the germ cell line.The evaluation of the distribution and colonization of MSC wasn’t possible due to ischemic necrosis observed in the injected testes.