Piezo-ICSI for Human Oocytes

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.