Control of hyperactivation in sperm.
نویسنده
چکیده
BACKGROUND Sperm hyperactivation is critical to fertilization, because it is required for penetration of the zona pellucida. Hyperactivation may also facilitate release of sperm from the oviductal storage reservoir and may propel sperm through mucus in the oviductal lumen and the matrix of the cumulus oophorus. Hyperactivation is characterized by high amplitude, asymmetrical flagellar bending. METHODS This is a review of the original literature on the mechanisms that regulate hyperactivation, including physiological factors and signaling pathways. RESULTS Computer-assisted semen analysis systems can be used to identify hyperactivated sperm by setting minimum thresholds for curvilinear velocity (VSL) and lateral head movement and a maximum threshold for path linearity. Hyperactivation is triggered by a rise in flagellar Ca(2+) resulting from influx primarily through plasma membrane CatSper channels and possibly also by release of Ca(2+) from a store in the redundant nuclear envelope. It requires increased pH and ATP production. The physiological signals that trigger the rise in Ca(2+) remain elusive, but there is evidence that the increased Ca(2+) acts through a calmodulin/calmodulin kinase pathway. Hyperactivation is considered part of the capacitation process; however, the regulatory pathway that triggers hyperactivation can operate independently from that which prepares sperm to undergo the acrosome reaction. Hyperactivation may be modulated by chemotactic signals to turn sperm toward the oocyte. CONCLUSIONS Little is known about exactly what triggers hyperactivation in human sperm. This information could enable clinicians to develop reliable fertility assays to assess normal hyperactivation in human sperm samples.
منابع مشابه
Changes in Motility Parameters of Mouse Spermatozoa in Response to Different Doses of Progesterone during Course of Hyperactivation
The aim of this study was to evaluate changes that occur in motility parameters of progesterone treated mouse spermatozoa during course of hyperactivation. Mouse spermatozoa treated with different doses of progesterone were videotaped after 10 min and 90 min of incubation. For each sperm, one second of movement of the head-midpiece junction was traced from the videotape and for each tracing sev...
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Background: Mammalian sperm are not ready to fertilize oocyte immediately after ejaculation. Sperm achieve this ability after undergoing the processes of capacitation and hyperactivation. Hyperactivation refers to a change in the motility pattern of the sperm. Pharmacological reagents and physical-mechanical forces have been used in sperm from a variety of species. Hydrostatic pressure is a cru...
متن کاملEffects of Different Doses of Progesterone on Motion Parameters of Mouse Spermatozoa During the Course of Hyperactivation
Purpose: To evaluate the changes that occur in the motility parameters of progesterone treated sperms during the course of hyperactivation. Materials and Methods: Spermatozoa treated with different doses of progesterone were videotaped after 10 min and 90 min. For each sperm, 1 sec. of movement of the head-midpiece junction was traced from the videotape. For each tracing, seven motility parame...
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ورودعنوان ژورنال:
- Human reproduction update
دوره 14 6 شماره
صفحات -
تاریخ انتشار 2008