Abstract
Bovine sperm motion in environments of various viscosities is studied. We used the semen of Japanese cattle and investigated the following parameters: the sperm velocity, the straight-line velocity, and the amplitude from the observed sperm trajectory. As the viscosity increased, the motility of the sperm decreased. On the other hand, the power expended by the sperm flagellum was of the same order of magnitude over the viscosity range of 0.0007-0.0226 Pa·s. Additionally, the increase in the viscosity brought about a change in the flagellum shape and an increase in the percentage of sperm with a nonrotating head. The existence of rotation caused a change in the sperm velocity, amplitude, and frequency of the flagellum. These results suggest that bovine sperm has evolved to swim effectively in the oviduct, which is a high-viscosity environment.
