Piezo-ICSI

Abstract

The Piezo-ICSI could perform the membrane breakage by applying a Piezo pulse which produced ultra-fast submicron forward momentum using flat-tipped micropipettes with no bevel or spike. Before performing the Piezo-ICSI, operation liquid was placed in the middle of the micropipette about 10-15 mm. Then the micropipette was inserted and clamped into the micropipette holder. The Piezo-micromanipulator drive unit was attached to the micropipette holder. After operation liquid was pushed to the tip of the micropipette, 7% PVP was aspirated into the micropipette. The sperm was then immobilized by applying a few Piezo pulses during the sperm’s tail was attached to the edge of the micropipette and aspirated into the micropipette. Without oocyte deformation, the micropipette was gently placed against the zona pellucida while Piezo pulses were applied, to allow the pipette to break through the zona pellucida and not the membrane. The sperm was advanced until the sperm head was near the tip of the micropipette, and the micropipette was advanced forward (to ∼60 % of the oocyte diameter) to stretch the membrane. The breakage of the membrane was performed by applying one Piezo pulse without aspirating the cytoplasm into the micropipette, and the sperm was injected into the oocyte. In our previous analysis, the calculated mean volume of cytoplasm aspirated into the micropipette with Conventional-ICSI (2746 ± 940 μm3) was significantly higher than with Piezo-ICSI (0 ± 0 μm3) (P < 0.05). In addition, significantly higher rates for survival (99% vs. 90%), fertilization (89% vs. 68%), good quality Day-3 embryo (55% vs. 37%), pregnancy (31% vs. 19%), implantation (31% vs. 19%), and live births (25% vs. 15%) were obtained when using the Piezo-ICSI than with the Conventional-ICSI (P < 0.05) (Hiraoka et al. JARG 2015). Moreover, the fertilization rate for Conventional-ICSI performed by our three embryologists was 66%, whereas the fertilization rate with Piezo-ICSI significantly improved to 82% (P < 0.05). The fertilization rates for Conventional-ICSI performed by our three embryologists I, II, and III were 60%, 74%, and 64%, respectively. The fertilization rates for Piezo-ICSI performed by our three embryologists I, II, and III were 80%, 83%, and 83%, respectively. The fertilization rates in case of each our embryologist using Piezo-ICSI was significantly higher than that for Conventional-ICSI (P < 0.05). After 20 procedures, the fertilization rates from our embryologists using Piezo-ICSI reached ≥80% per 20 oocytes. Our results indicate that Piezo-ICSI significantly improved the fertilization rates for the procedures performed by our three embryologists from 66% to 82%, and they became proficient in performing Piezo-ICSI after 20 procedures.