Ectopic autografting of testis tissue is a promising approach for studying 
testicular development, male germline preservation and restoration of male 
fertility. In this study, we examined the fate of various testicular cells in 
adult mouse testes following ectopic autografting at 1, 2, 4 and 8 weeks post 
grafting. Histological examination showed no evidence of re-establishment of 
spermatogenesis in autografts, and progressive degeneration of seminiferous 
tubules was detected. Expression of germ cell-specific proteins such as POU5F1, 
DAZL, TNP1, TNP2, PRM1 and PRM2 revealed that, although proliferating and 
differentiating spermatogenic germ cells such as spermatogonia, spermatocytes 
and spermatids could survive in autografts until 4 weeks, only terminally 
differentiated germ cells such as sperm persisted in autografts until 8 weeks. 
The presence of Sertoli and peritubular myoid cells, as indicated by expression 
of WT1 and ACTA2 proteins, respectively, was evident in the autografts until 8 
weeks. Interestingly, seminal vesicle weight and serum testosterone level were 
restored in autografted mice by 8 weeks post grafting. The expression of Leydig 
cell-specific proteins such as CYP11A1, HSD3B2 and LHCGR showed revival of 
Leydig cell (LC) populations in autografts over time since grafting. Elevated 
expression of PDGFRA, LIF, DHH and NEFH in autografts indicated de novo 
regeneration of LC populations. Autografted adult testis can be used as a model 
for investigating Leydig cell regeneration, steroidogenesis and regulation of 
the intrinsic factors involved in Leydig cell development. The success of this 
rodent model can have therapeutic applications for adult human males undergoing 
sterilizing cancer therapy.