Fig. 5

Calcium signaling at the site of sperm incorporation. The progression of calcium release at the micropyle was followed by using a suction pipette to position an oocyte such that the micropyle was visible. Calcium green dextran was then injected from the left and after a 10-min recovery period, images from transmitted light (upper panels) and calcium green fluorescence (lower panels) were recorded at 15 sec intervals. Unfertilized oocyte (A), 0.5 mpi (B), 1.0 mpi (C), 1.5 mpi (D) and 2.0 mpi (E). The position of the depression in the oocyte cortex caused by the micropyle is indicated by the white arrow. The fertilization cone is indicated by the black arrow. The clear cytoplasm at the animal pole which became apparent at 2.0 mpi is indicated by (*).The initial calcium release at the site of sperm fusion is barely recognizable in (B), but obvious in (C). It is also apparent that the initial calcium response at the site of sperm-egg interaction is strongly amplified once it reached the animal pole. Magnification is indicated by the bar, which represents 25 μm.