Effects of Medium on Blastocyst Formation, Cell Number and Percentage of ICM in Mice / 대한불임학회지

ABSTRACT

OBJECTIVE: The aim of this study was to evaluate the influence of different media on blastulation, mean cell number, percentage of inner cell mass (ICM) of total cells and ICM trophectoderm (TE) ratio in mice. MATERIALS AND METHODS: A total 552 two cell embryos were retrieved from ICR female mice (4 weeks old) at 48 hr after hCG injection (mated just after hCG injection) and cultured in MEM (n=276) or TCM (n=276) supplemented with 20% hFF. The grading of blastocysts from zona-intact (ZiB) to -escape (hatching and hatched, ZeB) was performed at 72 hours after culture. Total, TE and ICM cell numbers were analyzed by differential staining of blastocyst. Statistical analysis was performed using t-test with SigmaPlot-2001. P-values<0.05 were accepted as statistically significant. RESULTS: The blastulation rate in MEM (64.9+/-4.95%) was significantly higher (p=0.0031) than that in TCM (57.2+/-5.22%). No differences were found in the number of ZiB and ZeB between MEM (31.9+/-2.62, 33.0+/-4.58%), and TCM (27.2+/-4.28, 30.1+/-4.58%). A total 314 blastocysts (MEM=166; TCM= 148) were stained differentially. Mean cell number of blastocysts was significantly higher (p=0.0002) in TCM (73.1+/-3.3) than in MEM (61.7+/-2.5). Differential staining was successfully performed in 155 blastocysts (MEM=77; TCM=78). The percentage of ICM was significantly higher in MEM than in TCM (20.9+/-1.3 vs. 17.1+/-1.2%, p=0.0281). The ICMTE ratio was higher in TCM than in MEM (1 4.85+/-0.68 vs. 1 3.78+/-0.78, NS). CONCLUSION: These results show that MEM increase the blastocyst formation and percentage of ICM of total cells comparing with TCM in mice.