Figure 3.

[Ca2+]_i oscillations, measured as the ratio of Fura-2 fluorescence excited sequentially at 340 and 380 nm every 10 s. (A) maturing oocyte fertilised with ICSI. Due to technical reasons the first [Ca²⁺]_i spike was not recorded. (B) MII oocyte, which was fertilised by ICSI during maturation and was refertilised after completion of the maturation, (C) MII oocyte, which during maturation was subjected to sham microinjection and was fertilised after completion of the maturation, (D) MII oocyte, which matured in vitro, and was fertilised at the end of maturation.