Figure 4.

Simulation of InsP₃ induced Ca²⁺ release in eggs. Images are shown for a 2-dimensional simulation of the propagation of a Ca²⁺ wave in a mouse egg using a mechanism based upon Ca²⁺ induced InsP₃ formation. Images for each time series is shown in each of the rows. For the first row the only source of PIP₂ for making InsP₃ is at the boundary (the plasma membrane) and this does not cause a wave at all. The times for each image (in seconds) in the top row is indicated by numbers above each image. In the next three rows the source of Ca²⁺ induced InsP₃ formation is spaced at different distances. The time intervals for each image is indicated in the second row and it is then the same for each image going down in each column. In the first row the distance for the PIP₂ is 4 μm, and again no Ca²⁺ wave can be generated. With a PIP₂ source spaced at 3 or 2 μm we found that a Ca²⁺ wave can be generated. With a 2 μm separation a wave occurs that crosses the “egg” in ~1 s.