Study of pufferfish (Takifugu niphobles) sperm: Development of methods for short-term storage, effects of different activation media and role of intracellular changes in Ca2Â + and K+ in the initiation of sperm motility

On the other hand, both the osmolality and the ion composition of the media are essential factors which can modulate the sperm motility parameters. The osmolality of the activating medium was the most important factor in triggering pufferfish sperm motility, and osmolalities of 750-825 mOsm/kg were necessary to initiate this process, demonstrating that it appears to be a dose-independent mechanism. Regarding the ion composition of the activation media, this study has shown that despite the spermatozoa being able to initiate movement without any ion in the activation medium, the absence of ions can negatively affect the kinetic parameters of the spermatozoa. Finally, in natural conditions (seawater), the activation of sperm motility generates intracellular increases in Ca2 + and K+, suggesting that these ions play an essential role in the activation mechanism of pufferfish sperm.