Fig. 1.

a Schematic summary of solitary versus repetitive Ca²⁺ transients during fertilization across the animal kingdom. Examples of waves versus non-wavelike transients are listed for various animal groups, while also detailing models of Ca²⁺ transient initiation in each type of model (single versus multiple transients). b A representative recording of intracellular Ca²⁺ release patterns in a mouse oocyte undergoing in vitro fertilization (IVF) using a Ca²⁺-sensitive fluorescent dye (Rhod dextran in this case). The fluorescence is expressed as a ratio of the intensity divided by the starting fluorescence value. The arrow indicates time of sperm addition to oocytes. Figure adapted from Kashir et al. [46] and Kashir et al. [45] with permission