A comparison of in vitro culture systems for cat embryos

The aim of this study was to compare several culture systems for cat embryos. Domestic cat oocytes were matured in vitro (IVM), fertilized (IVF), and cultured individually or in groups in drops under oil (20 μL or 50 μL) and in 16 microwell dishes (Primo Vision®). Moreover, the effects of co-culture with a) uncleaved oocytes, b) homospecific and c) heterospecific co-culture with cat and sheep companion embryos were investigated using a time-lapse system. A higher proportion of blastocysts and hatching blastocysts was observed after culture in Primo Vision® dishes compared with the classical individual (p < 0.001) and group (p < 0.05) culture systems. Culture of presumptive zygotes 16 hpi and the presence of uncleaved oocytes did not reduce blastocyst development compared with culture of embryos 24 hpi without uncleaved oocytes. Co-culture with later-stage companion cator sheep embryos accelerated development of catembryos. The highest percentage of blastocysts was obtained in the group co-cultured with sheep embryos (54%). Moreover, the blastocyst cavity formed on average 10 h faster in this group than for the control group and for embryos co-cultured with cat embryos. The proportion of hatching blastocysts was similar in the co-cultures with cat and with sheep embryos (20% vs. 22%) and significantly (p < 0.05) than in the control group (12%).