Ovary cryopreservation and subsequent transplantation can enable researchers to preserve valuable transgenic animal strains. Some studies have indicated, however, that this process may impair ovary viability and recipient fertility. The authors investigated the effects of ovary vitrification followed by orthotopic transplantation in five strains of mice. They grafted fresh and frozen ovaries of 10-d-old mice into 4-week-old ovariectomized recipients. In addition to using wild-type strains (BALB/cAn and ICR/JCL), the authors used a transgene system that enabled them to identify whether offspring derived from the ovary of the recipient or that of the donor: they transplanted ovaries from one transgenic strain (LAP/rtTA) into wild-type C57BL/6J mice and into mice from a second transgenic strain (pTet/Cd226). The authors then determined the origin of the offspring born to these recipients using PCR. Ovary cryopreservation seemed to have no effect on the long-term fertility and reproductive characteristics of recipients and their offspring.