The domestic ferret (Mustela putorius furos) has become an excellent model for biomedical studies in areas such as infectious diseases, neurological disorders and reproductive biology. Other studies have revealed that ferrets have marked similarities to humans in airway structure and cell biology (Plopper et al., 1980; Leigh et al., 1986; Curtis et al., 1987; Sehgal et al., 1996; Duan et al., 1998). Furthermore, ferrets are a useful model for the study of lung infections caused by viruses such as influenza (Husseini et al., 1983; Durchfeld et al., 1991; Jakeman et al., 1991; Leigh et al., 1995; Fenton et al., 1999). These studies indicate that ferrets may serve as an excellent animal model for the study of airway diseases in humans. Ongoing research in our laboratory has the eventual goal of generating a ferret model for the study of cystic fibrosis, an inherited disorder affecting about 1 in every 3000 newborns among the Caucasian population. The present study describes embryo manipulation in ferrets, as a prelude to initiating genetic modelling approaches in this species.

Natural ovulation in ferrets is induced by mating and occurs 24–36 h thereafter (Robinson, 1918; Hammond and Marshall, 1934). In the absence of any hormonal treatment, a virgin female in oestrus generally ovulates six to ten oocytes after mating with a male (Chang, 1965; Mead et al., 1988). To date, only a few studies have investigated the effects of hormonal treatment on ovulation in ferrets, and none of these has achieved very high ovulation rates (Chang, 1965; Mead et al., 1988; Amstislavskii et al., 1997). Therefore, a more detailed investigation using different combinations of gonadotrophins is required to maximize the number of oocytes and embryos that can be retrieved from individual female ferrets. The first successful embryo transfer was performed in rabbits (Heape, 1890), and has since been applied to a variety of domestic and wild animals (Day, 1979; Kreamer et al., 1979; Dickman, 1982; Moor, 1982; Newcomb, 1982; Nicholas, 1993), including ferrets (Chang, 1968; Kidder et al., 1999b). However, there are no reports of embryo transfer in ferrets using embryos developed in vitro. The ability to culture ferret embryos in vitro and to produce live offspring by embryo transfer is critical for genetic manipulation of this species and the subsequent development of new animal models for human diseases.