Sperm capacitation

A process that is used to retrieve the spermatozoa in a semen sample that sperm capacitation the greatest probability of fertilising. Sperm capacitation is a natural process that takes place in semen after it has been ejaculated and it is essential for fertilising the ovum.

Capacitation is a remarkable process whereby spermatozoa prepare themselves for engagement with the oocyte. Although the existence of this process has been appreciated as a biological phenomenon for more than half a century, its molecular underpinnings still await clarification. We know that some of the major changes involve sterol oxidation and efflux from the plasma membrane, the anterior movement of lipid rafts, changes in the surface expression of a variety of proteins including hyaluronidase and receptors for the zona pellucida, an increase in intracellular cyclic adenosine monophosphate cAMP , the induction of tyrosine phosphorylation and the expression of hyperactivated motility. These changes are dependent on the presence of bicarbonate, to facilitate cAMP generation, maintain an alkaline intracellular pH and support an optimal level of reactive oxygen species generation and are enhanced by the presence of albumin to provide antioxidant protection to the plasma membrane and promote cholesterol efflux. In vivo , the rate at which sperm cells capacitate is carefully controlled in order to ensure that the release of capacitated spermatozoa from a post-insemination reservoir in the isthmic region of the oviduct is synchronized with ovulation. The factors that control these critical events are now being resolved, aided by proteomic studies that are providing critical definitive information on the range of receptors that exist in the sperm plasma membrane and define the manner in which these exquisitely complex cells interact with their environment.

Sperm capacitation

Federal government websites often end in. The site is secure. In mammals, fertilization occurs via a comprehensive progression of events. Freshly ejaculated sperm have yet to acquire progressive motility or fertilization ability. They must first undergo a series of biochemical and physiological changes, collectively known as capacitation. Capacitation is a significant prerequisite to fertilization. During the process of capacitation, changes in membrane properties, intracellular ion concentration and the activities of enzymes, together with other protein modifications, induce multiple signaling events and pathways in defined media in vitro or in the female reproductive tract in vivo. These, in turn, stimulate the acrosome reaction and prepare spermatozoa for penetration of the egg zona pellucida prior to fertilization. In the present review, we conclude all mainstream factors and pathways regulate capacitation and highlight their crosstalk. We also summarize the relationship between capacitation and assisted reproductive technology or human disease.

Regulation of protein phosphorylation during sperm capacitation.

Federal government websites often end in. The site is secure. Mammalian sperm must undergo a series of biochemical and physiological modifications, collectively called capacitation, in the female reproductive tract prior to the acrosome reaction AR. In the present review, we summarize some of the signaling events that are involved in capacitation. The activation of PKA during capacitation depends mainly on cyclic adenosine monophosphate cAMP produced by the bicarbonate-dependent soluble adenylyl cyclase. This activation of PKA leads to an increase in actin polymerization, an essential process for the development of hyperactivated motility, which is necessary for successful fertilization. Actin polymerization is mediated by PIP 2 in two ways: first, PIP 2 acts as a cofactor for phospholipase D PLD activation, and second, as a molecule that binds and inhibits actin-severing proteins such as gelsolin.

Federal government websites often end in. The site is secure. Mammalian sperm must undergo a series of biochemical and physiological modifications, collectively called capacitation, in the female reproductive tract prior to the acrosome reaction AR. In the present review, we summarize some of the signaling events that are involved in capacitation. The activation of PKA during capacitation depends mainly on cyclic adenosine monophosphate cAMP produced by the bicarbonate-dependent soluble adenylyl cyclase. This activation of PKA leads to an increase in actin polymerization, an essential process for the development of hyperactivated motility, which is necessary for successful fertilization. Actin polymerization is mediated by PIP 2 in two ways: first, PIP 2 acts as a cofactor for phospholipase D PLD activation, and second, as a molecule that binds and inhibits actin-severing proteins such as gelsolin. Tyrosine phosphorylation of gelsolin during capacitation by Src family kinase SFK is also important for its inactivation.

Sperm capacitation

Sperm capacitation refers to the physiological changes spermatozoa must undergo in order to have the ability to penetrate and fertilize an egg. This term was first coined in by Colin Russell Austin based on independent studies conducted by Austin and Min Chueh Chang and published in Since the initial reports and emergence of the term, the details of the process have been elucidated due to technological advancements. Recognition of the phenomenon was quite important to early in vitro fertilization experiments as well as to the fields of embryology and reproductive biology. These initial studies involved introducing sperm into the fallopian tubes of females of various animal species both hours before and immediately after ovulation.

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This review is focused on the principal molecular mechanisms that govern human sperm capacitation with particular emphasis in comparing all the reported evidence with the mouse model. B Biochem. Biomed Res. He published seminal works on oocyte maturation and deliberated extensively on the endocrine control of follicular development Edwards, , PMID Unresolved questions concerning mammalian sperm acrosomal exocytosis. Funahashi H, Nagai T. Ng, K. Therefore, transit through the female tract affords sperm to be modified by changes in the ionic environment that are not available in in vitro models. Despite confusion and some discrepancy in the study of capacitation, the concept remains integral to the study of fertilization. J Zhejiang Univ Sci B. To summarize, the multiple fluorescent methods used in our study to monitor boar sperm capacitation proved to be able to detect the temporal changes of the capacitation process.

Capacitation is the penultimate [1] step in the maturation of mammalian spermatozoa and is required to render them competent to fertilize an oocyte. In vivo , capacitation occurs after ejaculation , when the spermatozoa leave the vagina and enter the upper female reproductive tract. The uterus aids in the steps of capacitation by secreting sterol-binding albumin , lipoproteins , and proteolytic and glycosidasic enzymes such as heparin.

Bio Reprod. ROS and its dose-dependent mechanism in capacitation Many research have indicated that the production of reactive oxygen species ROS are expressed in the early period of capacitation. This suggests that bad sperm quality may arouse FOAD. Based on evidence available at the time, the conclusion was that the events of capacitation consisted of the unmasking of receptors on the sperm itself, rendering it capable of reacting to the environment of the female genital tract. Physiol Rev. Hyper-activated motility in sperm capacitation is mediated by phospholipase D-dependent actin polymerization. For its part, peroxynitrite is known to both inhibit tyrosine phosphatases and activate tyrosine kinases of the Src family Minetti et al. Conclusions Our study compared four largely used methods used to characterize capacitation process, highlighted their differences and showed that all are able to detect capacitation progress, CTC and ACR. Because PKA has multiple targets, phosphorylation of a given substrate may occur without affecting others by the action of A-kinase-anchoring proteins AKAPs Carnegie et al. Correlation between the capacitation state and protein tyrosine phosphorylation. Mechanism of sperm capacitation and the acrosome reaction: role of protein kinases. Andrology 5, — J Zhejiang Univ Sci B. Involvement of protein kinase A and A kinase anchoring protein in the progesterone-initiated human sperm acrosome reaction.