TRPV1: a channel for mammalian sperm thermotaxis?
A number of studies have proposed that mammalian spermatozoa are guided within the oviduct towards the fertilization site by thermotaxis. Thermotaxis relies on a temperature gradient within the oviduct originated by a drop of temperature occurring at the utero-tubal junction during ovulation (1,2). This temperature gradient allows capacitated rabbit, bull, mouse and human spermatozoa to orientate their swim away from the utero-tubal junction, towards the warmer temperature, where the oocyte awaits (3-5). Based on empirical proofs, Bahat et al. (2012) (6) determined that spermatozoa can sense temperature changes as little as 0.0006ºC and change the direction of swimming towards the warmer temperature. This discovery leads to the intriguing questions of what is the cellular machinery conferring such extraordinary sensitivity to the spermatozoa.