In vitro techniques in fox reproduction

Abstract The domestic blue fox ( Alopex lagopus ) is extensively farmed in Scandinavia, and represents a genetic reserve, as well as a model for basic reproductive studies for the wild arctic fox, which is a canid species threatened by extinction. The development of in vitro techniques may be a way to preserve genetic material from the wild fox population. The scope of this paper was to review the authors' first experiments with maturation and fertilization in vitro (IVM, IVF) of fox oocytes. IVF was attempted after collection of in vivo matured oocytes 2 days after maximum vaginal electrical resistance, from 6 farmed blue fox females in natural oestrus. IVM was carried out in oocytes collected from ovaries of 29 vixens in pro-oestrus, i.e. prior to the preovulatory LH peak. The oocytes for IVM were cultured in bovine IVM media (M199, 10% FCS, w/wo FSH), but without LH. In the IVF experiment, 2 of 36 inseminated ova developed beyond the 4-cell stage. One embryo developed to a morula 144 h after insemination. In the IVM experiment 325 oocytes were evaluated, 91% (w/FSH) vs 78% showed germinal vesicle breakdown. GVBD was observed after 24 h in culture (19% w/FSH vs 27%), MI was reached at 48 h (70% vs 40%), MII at 48–72 h (48% vs 22%), but the majority of MII were seen at 96 h after insemination (73% vs 66%). Duration of IVM (96 h) was somewhat longer than observed in vivo (72 h). Although dissociation of cumulus cells was observed, corona radiata cells were tightly connected with the oocytes, suggesting incomplete cytoplasmatic maturation.