Embryo cryopreservation and transfer in Mustelidae: Approaches to ex situ conservation of the endangered European mink

Successful cryopreservation of Mustelidae embryos was proved by development of frozen–thawed farmed European polecat (model species) embryos both in vitro and in vivo. Intra- and interspecies embryo transfer was performed between the endangered European mink (Mustela lutreola) and related Mustelidae species: European polecats (Mustela putorius) and domestic ferrets (Mustela putorius furo). Intraspecies embryo transfer was successful if more than two embryos were transferred. However, straightforward interspecies embryo transfers between different Mustelidae species have not resulted in term kits. Nonetheless, this paper demonstrates the possibility to overcome interspecies pregnancy failure by using European polecat/European mink hybrid females (called honoriks or nohoriks) as recipients for European mink embryos. Integrated package of reproductive technologies, i.e. production of polecat/mink hybrids, cryopreservation and subsequent transfer of European mink embryos into uterine horns of hybrid females is recommended as an option for ex situ conservation of the European mink.