Syngenic grafting of a whole juvenile male gonadal tissue into the adult testes confers successful spermatogenesis in mice

ObjectiveTo examine whether functional spermatozoa can be obtained when a whole male gonadal tissue (testes, epididymides, and fat) isolated from neonatal mice is grafted underneath adult mouse testes.MethodsNeonatal (1-day-old) male gonadal tissue, isolated from enhanced green fluorescent protein (EGFP)-transgenic (Tg) mice (C57BL/6-Tg(ACTB-EGFP)1Osb/J), was inserted deep in the testis of a non-Tg recipient mouse through a tunica albuginea incision. Two months after transplantation, the fluorescent grafted tissues were retrieved from recipient mice.ResultsHistological analysis demonstrated that epididymal architecture was well developed and that spermatogenesis in the testis occurred in 30–60% of each seminiferous tubule of all the grafted tissues examined. Interestingly, motile spermatozoa could be successfully retrieved from the portion corresponding to the cauda epididymis in 1 of the 7 transplants obtained. These obtained spermatozoa had transgenes and could support embryonic development when intracytoplasmic sperm injection was performed using frozen-thawed spermatozoa.ConclusionThis present technique will be useful for study in various biological fields including the rescue of Tg lines with lethal postnatal phenotypes and cloned animals that die immediately after birth.