Untersuchungen chromosomaler Aberrationen an Blastozyten von superovulierten Kaninchen nach bis zu 5tägiger Lagerung des zur Besamung verwendeten Spermas bei verschiedenen Temperaturen

Cryosurvival of rabbit embryos obtained after superovulation with corifollitropin alfa with or without LH

The efficiency of an embryo bank depends on provision of optimal conditions for recovery, cryopreservation and transfer to a breed or strain. In this sense, increasing the number of embryos available using superovulation should improve the cryobank efficiency. However, vagueness of response to conventional protocols to control or increase ovarian response and the quality of oocytes and embryos and their cryotolerance remain a challenge. The aim of our study was to evaluate the effect of corifollitropin alpha (CTP) and a recombinant human FSH (rhFSH), alone or supplemented with rhLH, on embryo cryosurvival by in vitro development and OCT4 and NANOG mRNA abundance at blastocyst stage and offspring rate. In vitro development of vitrified embryos was not significantly affected by superstimulation with or without rhLH supplementation, resulting in similar development rates to those of the control groups (fresh and vitrified embryos from non-superstimulated donor does). Blastocysts developed from vitrified embryos showed higher levels of OCT4 transcript abundance than fresh control, while NANOG transcript abundance was only higher in the blastocysts developed from vitrified embryos after superstimulation treatment in comparison with control groups. The implantation and offspring rates at birth were negatively affected by supplementation with rhLH. Both rhFSH or CTP vitrified embryo groups showed an implantation rate similar to those of the control groups, but an offspring rate lower than control. In conclusion, embryos produced using corifollitropin alpha did not compromise the cryosurvival of vitrified embryos in the rabbit. In addition, this study points out the negative effect of rhLH supplementation in terms of offspring rate on embryo vitrification.

Effect of eCG dose and ovulation induction treatments on embryo recovery and in vitro development post-vitrification in two selected lines of rabbit does

The aim of this work was to evaluate the effect of different doses of eCG administered subcutaneously (0, 50 and 200 IU) and the hormonal induction of ovulation (GnRH or hCG) on embryo recovery and in vitro development of embryos post-vitrification in two selected lines of rabbit does. The two selected lines were line V (selected for the litter size at weaning) and line R (selected for growth rate). Administration of 200 IU of eCG significantly increased ovulation rate (19.2 +/- 1.2 versus 15.5 +/- 1.1 and 12.2 +/- 1.3, and the number of haemorrhagic follicles (13.8+/-1.6 versus 3.8+ /- 1.4 and 3.8 +/- 1.7), but significantly decreased recovery rate (28.8 +/- 6.3 versus 47.7 +/- 5.7 and 48.7 +/- 6.7, 200 IU versus 50 IU and 0 IU eCG, respectively), the number of normal embryos recovered per doe with at least one embryo (5.8 +/- 0.9 versus 8.2 +/- 0.9, 200 IU versus 50 IU eCG doses) and the in vitro development of embryos post-vitrification (51.9% versus 66.1%, 200 IU versus 50 IU eCG doses, respectively). Inducing ovulation with hCG significantly increased ovulation rate when compared with GnRH (17.3 +/- 0.8 versus 13.8+/-1.4), but no significant differences in embryo recovery and embryo development post-vitrification were observed between the two treatments. No significant differences were observed between the two selected lines in ovulation and recovery rates, the number of haemorrhagic follicles and the number of recovered embryos per doe. However, the post-vitrification in vitro rate of development was 59.7% for line R and 51.9% for line V (p < 0.05). It was concluded that the use of 50 IU of eCG subcutaneous with hCG or GnRH prior to embryo cryopreservation programmes in rabbits achieves the best results for embryo recovery, with the best development of recovered embryos post-vitrification.