Reconstruction of sperm swimming paths in a chemical gradient. (A) Trajectory of the cell shown in Fig. 2 before and after the release of resact. (B) Numerical reconstruction of the swimming path using the time derivative dF_r/dt and the speed. The reconstructed path reproduces many of the essential features of the original path. (C) Experimental Ca²⁺ signal and speed of the sperm cell used for the reconstruction. The release of resact from the caged derivative occurs at t = 0 (dashed line).