Sperm thermotaxis, the active orientation of sperm swimming according to a
temperature gradient has been suggested to act as a long-range guidance mechanism in
the oviduct during fertilization, between the cooler sperm storage site and the warmer
fertilization site. In this process capacitated spermatozoa can sense even very shallow
temperature gradients. They respond to the changing temperature by modulating their
flagellar beating. The outcome is a higher frequency of turns and hyperactivation
events when the temperature drops, and a rather linear swimming when they sense a
temperature increase. In this way they are guided towards the warmer temperature.
Keywords: Flagellar shape, Hyperactivation, Sperm guidance, Sperm velocity.
