Ho H C, Suarez S S
Department of Biomedical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA.
Reproduction. 2001 Oct;122(4):519-26. doi: 10.1530/rep.0.1220519.
Hyperactivation is a movement pattern observed in spermatozoa at the site and time of fertilization in mammals. It may be critical to the success of fertilization, because it enhances the ability of spermatozoa to detach from the wall of the oviduct, to move around in the labyrinthine lumen of the oviduct, to penetrate mucous substances and, finally, to penetrate the zona pellucida of the oocyte. The movement of hyperactivated spermatozoa appears different under different physical conditions and in different species, but basically it involves an increase in flagellar bend amplitude and beat asymmetry. Presumably, there is a signal or signals in the oviduct to initiate hyperactivation at the appropriate time; however, none has yet been identified. There is evidence that the source of the signal is follicular fluid, yet spermatozoa are known to hyperactivate before ovulation would release the fluid into the oviduct. Although the signal transduction cascade regulating hyperactivation remains to be described completely, it is clear that calcium ions interact with the axoneme of the flagellum to switch on hyperactivation. The process may also involve increases in intracellular cAMP, which at least is required to support motility in general. Although hyperactivation usually occurs during capacitation, the two events are regulated by different pathways.
超激活是在哺乳动物受精部位和时间观察到的精子运动模式。它可能对受精成功至关重要，因为它增强了精子从输卵管壁脱离的能力，在输卵管迷宫般的管腔中移动的能力，穿透黏液物质的能力，以及最终穿透卵母细胞透明带的能力。超激活精子的运动在不同的物理条件下和不同物种中看起来有所不同，但基本上它涉及鞭毛弯曲幅度的增加和摆动不对称性。据推测，输卵管中存在一个或多个信号，在适当的时候启动超激活；然而，尚未发现任何信号。有证据表明信号源是卵泡液，但已知精子在排卵将卵泡液释放到输卵管之前就会超激活。尽管调节超激活的信号转导级联反应仍有待完全描述，但很明显钙离子与鞭毛的轴丝相互作用以开启超激活。这个过程也可能涉及细胞内cAMP的增加，至少一般来说它是维持运动所必需的。尽管超激活通常发生在获能期间，但这两个事件由不同的途径调节。
