Figure 2.

Ca^{2 +} responses evoked in human sperm by uncaging of Ca^{2 +} in the flagellum. Cells were labelled with fluo-4 and loaded with caged Ca^{2 +} (NP-EGTA), then stimulated by an uncaging flash (360 nm laser) at the central flagellum (shown by arrow) while collecting images at 33 Hz. Changes in fluorescence, assessed at each of the positions shown by coloured circles in panel ‘a’, are plotted (normalised to minimum and maximum) in panel ‘b’ using the same colour code. Green, neck; yellow-midpiece; red, proximal flagellum; light blue, mid-distal flagellum; dark blue, distal flagellum.