Vitrification of Mouse Blastocyst

Lee, Yu Jin; Kim, Mi Young; Lee, Seok Won; Lee, Yu Il

Abstract

OBJECTIVE
The aim of this study was to compare the survival and developmental rate of two vitrification solutions for the vitrification of mouse expanded blastocysts.
METHODS
Mouse embryos were obtained at 2 cell stage and cultured to expanded blastocyst stage in Human Tubal Fluid (HTF) medium supplemented with 10% serum substitute supplement (SSS). The vitrification solutions used were EFS40 and VS. EFS40 consisted of 40% ethylene glycol, 18% ficoll, and 0.5 M sucrose while VS consisted of 20% ethylene glycol, 20% DMSO, and 10% 1,3-butanediol diluted in Dulbecco's phosphate-buffered saline (DPBS) medium supplemented with 10% calf serum (CS). Toxicity was tested by exposing expanded blastocysts to vitrification solution. The vitrification procedure used for EFS40 was performed in three steps, after which they were warmed in 5 steps with 0.5 M sucrose. VS was performed in two steps, after which they were warmed with 1.0 M trehalose. Recovery, survival and hatching rate per expanded blastocysts recovered were compared between two groups.
RESULTS
In toxicity test, survival and hatching rate of EFS40 group were 95% and 100%, respectively. In contrast, survival and hatching rate of VS group were 100% and 87.5%, respectively. After vitrification and warming in solution, recovery rate for EFS40 group was 73.7% whereas recovery rate for VS group was 66.5%. After 24 h culture, survival and hatching rate were 80.5% and 20.7% for EFS40 and 66% and 0% for VS group, respectively. After 48 h culture, survival and hatching rate were 69% and 33.3% for EFS40 and 58.3% and 1.9% for VS group, respectively. Survival and hatching rate in EFS40 group were significantly higher than those found in VS group.
CONCLUSION
The EFS40 solution was better than VS solution for vitrification of mouse expanded blastocysts.