Objective To evaluate the safety and efficiency of an improved shape of opening for mechanical assisted hatching （AH） on the in virto development of mouse embryos. Methods A total of 622 KM BAI mouse embryos in 2-cell-4-cell stage were randomly divided into group A, group B and control group. A new mechanical AH method by improving the shape of opening in the ZP was used in group A, and a ＂-/ ＂-shaped opening was created. A ＂＋ ＂ -shaped opening was made in group B, while no opening was made in control group. Comparisons have been made among the three groups with regard to the duration of AH, the blastocyst formation and complete hatching rate, etc. Results The duration of AH in group A （43.25 ±3.46 s） was significantly shorter than that in group B （52.81 ±4.32 s, P 〈0.05）. The blastocyst formation rate on d 5 was not significantly different among the three groups （92.27%, 93.66% and 94.92% respectively, P 〉0.05）. The complete hatching rate of blastocysts on d 6 between group A and group B was no statistical difference （94.09% vs 92.71%, P 〉0.05）, but significantly higher than that in control group （43.32%, P 〈0.001）. No significant difference in the percentage of grade 1 blastocysts was found among the three groups on d 5 （85.22%, 82.81% and 86.63% respectively, P 〉0.05）. Conclusion R could enhance the process of embryo hatching and facilitate the hatching rate of blastocysts by using the improved mechanical AH method, which is of safety and efficiency to mouse embryo in the in vitro development.
Ai-jun ZHANG Yun FENG Xiao-yan HUANG Lan XLA Yi-juan SUN Yan LI
