Phospholipase C-ζ-induced Ca2+ oscillations cause coincident cytoplasmic movements in human oocytes that failed to fertilize after intracytoplasmic sperm injection

ObjectiveTo evaluate the imaging of cytoplasmic movements in human oocytes as a potential method to monitor the pattern of Ca2+ oscillations during activation.DesignTest of a laboratory technique.SettingUniversity medical school research laboratory.Patient(s)Donated unfertilized human oocytes from intracytoplasmic sperm injection (ICSI) cycles.Intervention(s)Microinjection of oocytes with phospholipase C (PLC) zeta (ζ) cRNA and a Ca2+-sensitive fluorescent dye.Main Outcome Measure(s)Simultaneous detection of oocyte cytoplasmic movements using particle image velocimetry (PIV) and of Ca2+ oscillations using a Ca2+-sensitive fluorescent dye.Result(s)Microinjection of PLCζ cRNA into human oocytes that had failed to fertilize after ICSI resulted in the appearance of prolonged Ca2+ oscillations. Each transient Ca2+ concentration change was accompanied by a small coordinated movement of the cytoplasm that could be detected using PIV analysis.Conclusion(s)The occurrence and frequency of cytoplasmic Ca2+ oscillations, a critical parameter in activating human zygotes, can be monitored by PIV analysis of cytoplasmic movements. This simple method provides a novel, noninvasive approach to determine in real time the occurrence and frequency of Ca2+ oscillations in human zygotes.