Fig. 3. Sperm flagellar waveform analysis. (A) The initial six video frames in a time series of images (48 x 48 µm) of a sperm collected at 30 Hz. (B) The flagellar beat envelope was visualized from a composite of all 30 images collected in the complete 1 second series. The flagellar beat amplitude is indicated by the orthogonal arrow placed 25 µm along the midline of the flagellar beat axis. (C) The flagellar waveform in each image in A was fitted with a sine function. The original, superimposed grayscale images were overlaid with the (colored) best-fit curves. (D) Regression analysis of the phase lags of the fitted sine functions in a longer segment of this series yields the flagellar beat frequency. The slope of the regression line (39.8 rad second^-1) corresponds to a beat frequency of 6.34 Hz.

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