Fig. 4. Relationship between swimming velocity and beat frequency of glycerol-treated and intact sperm. Photographs were taken from 5 s after dilution to the end of sperm motility. Velocity and beat frequency of intact and glycerol-treated sperm were calculated from photographs. (A) Relationship between swimming velocity and beat frequency of glycerol-treated (open circles) and intact sperm (filled squares). The regressions are y=7.0x–11.1 for intact sperm (r²=0.8, P<0.0001, N=49) and y=2.2x+22.6 for glycerol-treated sperm (r²=0.6, P<0.0001, N=35). (B,C) Trajectories taken at 0.5 s exposures for intact (B) and glycerol-treated(C) sperm. Schema of the trajectory are represented below each photograph. Bars, 100 µm (N=3).