Ca2+ influx-dependent refilling of intracellular Ca2+ stores determines the frequency of Ca2+ oscillations in fertilized mouse eggs

► Ca2+ influx and uptake during Ca2+ oscillations in mouse eggs are analyzed. ► Ca2+ influx is transiently activated after each Ca2+ release in the oscillations. ► Refilling rate of Ca2+ stores is dependent on Ca2+ influx rate. ► Oscillation frequency is determined by the rate of replenishing Ca2+ stores. ► STIM/Orai-mediated SOCE does not contribute for maintaining Ca2+ oscillations.