Survival of Two-step Open-pulled Straw Vitrification of Mouse Eight-cell Embryos

Objective To establish potentially an effective and easy method for the vitrification of embryos from laboratory animals, domestic animals and human . Methods The experiments were conducted at 37℃ hot plate and 25℃ room temperature to cryopreserve mouse eight-cell embryos with EDFS30 (an ethylene glycol-based vitrification solution) in Open-pulled Straw (OPS). In the two-step OPS method, the superovulated embryos were first pretreated with 10% EG+10% DMSO for 30s, then exposed to EDFS30 for 15s, 25s, 35s, 45s or 60s and then immersed in liquid nitrogen. After warming, the survival of embryos was assessed by their development to blastocysts or to term after transfer. Results The higher blastocyst rates of vitrified embryos were 95.6%, which were similar (P0.05) to that (93.0%) of control. The embryos derived from the best vitrified group or fresh eight-cell embryos (used as control) after culture for 1 to 3h were transferred to 63 to 67h pseudo-pregnant female mice. Twenty-three fetuses were obtained from 4 of 11 recipients which had received 165 vitrified-warmed embryos. In the pregnant recipients, the percentage of transferred embryos developed to young in the treated group (38.3%) and control (37.9%) showed no significant difference (P0.05). Conclusion The mouse eight-cell embryos could survive cryopreservation by vitrification with EDFS30 in OPS.