ABSTRACT
Since the first successful pregnancies achieved by intracytoplasmic sperm injection (ICSI) were reported, ICSI has become an essential technique in assisted reproductive technology (ART). ICSI uses micropipettes with a spiking tip to penetrate the zona pellucida and membrane. Then, the cytoplasm is usually aspirated into the micropipette for membrane breakage (conventional-ICSI). The survival and fertilization rates of mouse oocytes after conventional-ICSI were as low as 16% and 8%, respectively. Kimura and Yanagimachi applied a piezo drive unit, mercury, and a micropipette with a flat tip for mouse ICSI. The membrane breakage could be performed semi-automatically by combining these types of equipment without cytoplasmic aspiration into the micropipette (piezo-ICSI). These authors reported significantly higher survival and fertilization rates (80% and 78%) compared to those of conventional-ICSI (16% and 8%). Therefore, the piezo-ICSI may be effective not only for mouse oocytes but also for human oocyte ICSI. However, only five papers are available that assessed the effectiveness of piezo-ICSI compared to conventional-ICSI for human oocytes. All of these five papers reported significantly higher fertilization rates compared to those of conventional-ICSI. The goal of the piezo-ICSI protocol described here is to improve the clinical results of ICSI compared to the conventional-ICSI.