| Assisted hatching (AH) is one of efficient methods that promoting pre-implantation embryos hatching from zona pellucida. One of the problem in clinical practice is the low ratio of embryo implantation in in vitro fertilization-embryo transfer procedure. AH is widely employed for increase the ratio of blastocyst hatching and embryo implantation. To date, techniques of AH treatment include mechanical method, chemical drug treatment, laser or piezo penetration. For AH treatment, different protocols were used, including penetrating a hole through zona (zona-hole) or making zona thinner (zona-thin). However, regarding to these approaches, which one is more efficient and which stage embryo should be selected for treatment have not been fully investigated. Here, by employing method of piezo, different stages of mouse oocytes and embryos were employed for treatment with approaches of zone-hole and zona-thin. The ratio of embryo development as well as blastocyst hatch were calculated to figure out the most efficient AH protocols.Four kinds of piezo based AH methods were used in this study, including: (1) making small hole (OD=10 μm) on zona (small hole, SH); (2) making large hole (OD= 50 μm) on zona (large hole, LH); (3) making zona thinner in length of 50 μm (small length thinner, ST); (4) making zona thinner in length of 120 μm (large length thinner, LT). These four kinds of treatments were applied to oocytes of MⅡ stage, embryos of 2-cell,4-cell and morula stages after IVF.Our results indicated that SH treatment gave the highest ratio of blastocyst hatching, and most of embryos were in hatching but not hatched stage. Compared to SH, LT treatment gave the highest ratio of hatched blastocyst. We also found that embryos of morula is the best for AH treatment. In conclusion, methods of SH conducted on morula embryos will obtain the highest ratio of blastocyst hatching. This study provides the basic data for promoting the application of AH in human embryos. |
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