Stage-Dependent Viability of Mouse Preimplantation Embryos Vitrified with Sugar-containing Solutions.

The aim of the work is to determine the susceptibility of mouse preimplantation embryos to vitrification at different developmental stages. The experiment was carried out in embryos at 1-cell, morula and blastocyst stages. As a vitrification solution, a mixture of 2.5 M dimethylsulphoxide + 2.5 M propylene glycol (DP), DP + 1.0 M sucrose (DPS) or DP + 0.16 M raffinose (DPR), was used. The in vitro survival, evaluated by the development into a late blastocyst stage in vitro, of control and vitrified mouse embryos was examined. A high survival rate (80%) after vitrification was obtained for 1-cell embryos after a 15 sec-exposure to DPS. High survival rates for morulae (91-96%) and relatively low survival rates for blastocysts (30-55%) were observed after vitrification in either DPS or DPR after short exposures (within 30 sec). In vivo survival rate for each embryos vitrified in DPS by a short exposure (within 30 sec) at 1-cell, morula or blastocyst stage was 56, 53 or 40%. Though the rates for 1-cell and molura stages were comparable with those in control embryos (55 and 58%), the rate for blastocyst stage was significantly lower (P<0.05) than that in control embryos (56%). Thus, the proposed vitrification procedure can be useful in the cryopreservation of mouse preimplantation embryos at 1-cell and morula stages.