Fig. 1. Temporal patterns of Ca²⁺ changes in the cytoplasm and nucleus in normally fertilized oocytes. To monitor the Ca²⁺ changes, 10 kDa CGD (A) or 70 kDa CGD (B) was injected into the cytoplasm, or 70 kDa CGD was injected into the nucleus (C). The relative fluorescence levels of CGD (F/F₀ values) were calculated in the cytoplasmic and nuclear regions separately. The steep increases in F/F₀ (arrowheads in B and C) indicate the leakage of 70 kDa CGD through the nuclear envelope. A pair of right panels shows fluorescence images before (top) and after (bottom) each fluorescence measurement. All of the oocytes underwent GVBD on schedule (at 10 minutes) and then developed to early trochophores.