Initiation of sperm motility in teleosts.

In salmonid fish (rainbow trout and chum salmon) or freshwater cyprinid fish (goldfish), change of potassium concentration or osmolality of the environment surrounding the spermatozoa at spawning in fresh water directly affect the flagellum and regulate the initiation of sperm motility. A change in these external factors induces intraflagellar cAMP through some changes of plasma membrane in flagellum and cAMP triggers the initiation of axonemal movement through activation of cAMP-phosphorylation system in initiation of sperm motility in teleosts.