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

Objective: To evaluate the imaging of cytoplasmic movements in human oocytes as a potential method to monitor the pattern of Ca(2+) oscillations during activation.

Design: Test of a laboratory technique.

Setting: University 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 Ca(2+)-sensitive fluorescent dye.

Main Outcome Measure(s): Simultaneous detection of oocyte cytoplasmic movements using particle image velocimetry (PIV) and of Ca(2+) oscillations using a Ca(2+)-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 Ca(2+) oscillations. Each transient Ca(2+) 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 Ca(2+) 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 Ca(2+) oscillations in human zygotes.