Most fertilization failures after ICSI are caused by failure of oocyte activation defects. But, to date, there is no effective method to overcome this obstacle. To investigate the effect of mechanical stimulation on fertilization failures, investigators plan to recruit women undergoing ICSI treatment cycles. The retrieved sibling oocytes from the patients were randomly divided into two groups. The control group conducted the standard ICSI procedure, while the experimental group conducted the modified ICSI procedure.Consequently, the fertilization rate, 2PN (two pronuclei) rate, 1PN rate, oocyte degradation rate,and exploitable embryos on D3 were recorded to evaluate ICSI cycle outcomes.

Normal fertilization is the critical for the success of ICSI. To investigate the effect of mechanical stimulation on fertilization, investigators plan to recruit women undergoing ICSI treatment cycles. Exclusion criteria: Patients older than 40 years, the maturation oocytes less than 6. The retrieved sibling oocytes from the patient were randomly divided into two groups. The control group conducted the standard ICSI procedure, while the experimental group conducted the modified ICSI procedure. The modified ICSI procedure involved a micromanipulation mechanical stimulation between insertion of the microinjection needle into the oocyte and expulsion of the spermatozoon from the needle to the ooplasm, without additional reagents treatment. Consequently, the fertilization rate, 2PN rate, 1PN rate, oocyte degradation rate, and exploitable embryos on D3 were recorded. The investigators aim to evaluate whether the mechanical stimulation can be used to improve the normal fertilization and embryo quality in ICSI cycles.

Inclusion Criteria:

• oocytes number ≥ 8;
• women undergoing intracytoplasmic sperm injection cycle.

Exclusion Criteria:

• maturation oocytes number less than 6.