What controls polyspermy in mammals, the oviduct or the oocyte?

Coy, Pilar; Sánchez, Manuel A. Bueno

doi:10.1111/j.1469-185x.2009.00117.x

Cited by 83 publications

(54 citation statements)

References 158 publications

(226 reference statements)

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“…After the secretion of the cortical content into the perivitelline space, this will lead to modifications of the zona pellucida structure [20][21][22][23]. In some species, this has been characterized as "zona hardening" defined as resistence to proteolytic digestion resulting in a zona pellucida that cannot be penetrated by acrosome-reacted sperm, and also cannot be recognized by acrosome-intact sperm [24][25][26]. Therefore, successful fertilization of an oocyte depends on three independent and quite differently organized membrane fusion events.…”

Section: Introductionmentioning

confidence: 99%

Membrane Fusions During Mammalian Fertilization

Gadella

Evans

2011

Advances in Experimental Medicine and Biology

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Successful completion of fertilization in mammals requires three different types of membrane fusion events. Firstly, the sperm cell will need to secrete its acrosome contents (acrosome exocytosis; also known as the acrosome reaction); this allows the sperm to penetrate the extracellular matrix of the oocyte (zona pellucida) and to reach the oocyte plasma membrane, the site of fertilization. Next the sperm cell will bind and fuse with the oocyte plasma membrane (also known as the oolemma), which is a different type of fusion in which two different cells fuse together. Finally, the fertilized oocyte needs to prevent polyspermic fertilization, or fertilization by more than one sperm. To this end, the oocyte secretes the contents of cortical granules by exocytotic fusions of these vesicles with the oocyte plasma membrane over the entire oocyte cell surface (also known as the cortical reaction or cortical granule exocytosis). The secreted cortical contents modify the zona pellucida, converting it to a state that is unreceptive to sperm, constituting a block to polyspermy. In addition, there is a block at the level of the oolemma (also known as the membrane block to polyspermy). IntroductionFertilization of the oocyte involves three membrane fusion events [1] namely, (1) a preparative series of secretion membrane fusions at the apical sperm surface known as acrosome exocytosis [2]. The membrane fusions are induced when the sperm cell binds to specific zona binding proteins at the sperm surface [3][4][5][6][7]. The acrosome exocytosis is a multipoint membrane fusion event between the sperm plasma membrane and the outer acrosomal membrane (see Fig. 5.1 [8,9]) and the exposed acrosomal content is required for sperm to penetrate the zona pellucida [10][11][12]. This so-called zona drilling effectively takes place because the sperm at this stage also has acquired hyperactivated motility [13]. (2) After zona penetration the sperm enters the perivitelline space where it can bind and fuse with the oocyte plasma membrane [14,15]. This is the actual fertilization fusion in which the contents of the sperm are delivered into the oocyte cytoplasm. The plasma membrane of the equatorial segment (see Fig. 5.1) is the site where proteins are located that orchestrate sperm-oocyte binding and fusion [16]. (3) In order to prevent polyspermy the oocyte has to activate defense systems to block redundant sperm-oocyte fusion [17]. To this end the first fertilizing sperm delivers activation factors

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Section: Introductionmentioning

confidence: 99%

Membrane Fusions During Mammalian Fertilization

Gadella

Evans

2011

Advances in Experimental Medicine and Biology

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“…[16][17][18][19] In addition, heparin and heparin-like molecules, for example, glycosamineglycan-sulphates (GAGs), were able to induce decondensation of intact spermatozoan nuclei and regulate polyspermy in vitro. 20,34,35 Heparin binding-site density might be related to the ability of human spermatozoa to successfully undergo the acrosome reaction. 36 Heparin has also been hypothesized to stabilize the zona pellucida system (tesistance to pronase) through binding to oviduct-specific glycoprotein.…”

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confidence: 99%

Rat recombinant β-defensin 22 is a heparin-binding protein with antimicrobial activity

Diao¹,

Yu²,

Sun³

et al. 2010

Asian J Androl

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Approximately 40-50 b-defensins are predominantly expressed in the male reproductive system of mammals. This selective expression raises the question as to the roles of these molecules in innate immunity and fertility in the male reproductive tract. Rat b-defensin 22 is an epididymis-specific b-defensin expressed in segments 12-14 of the epididymis. This protein contains both b-defensin and lectin signature sequences, yet its antimicrobial activity and carbohydrate-binding ability have not been shown. We herein demonstrated the antimicrobial activity of recombinant rat b-defensin 22 against Escherichia coli and Candida albicans. Its lectin-like activity was also investigated by demonstrating its binding ability with heparin beads. This heparin-binding activity implies some potential roles for this defensin in determining the fertilisation capabilities of sperm.

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“…Although there is much information in the literature on the genetics and biochemistry of the outer layers, in particular the zona pellucida [4,38,42,57,79,106], we know little about their topographical constitution and if indeed sperm entry is piloted to a specific site. Recently chemical modulation of the zona by oviductal-specific glycoproteins before the oocyte encounters the spermatozoon has been described and this may also be involved in the fine tuning of sperm-oocyte interactions in mammals [14,15]. Finally, although the plasma membrane of the human metaphase ll oocyte appears at the scanning electron microscope to be unpolarized, a study with surface lectins may be instrumental in showing whether or not spermatozoa may fuse at any site around the plasma membrane [87].…”

Section: Sperm-oocyte Interaction In Mammalsmentioning

confidence: 99%

“…In eukaryotes, if more than one sperm nucleus interacts with the female nucleus abnormal cleavage will occur and death of the embryo ensues. Laboratory images of oocytes with many spermatozoa attached to their surface have led to the idea that following interaction with the successful spermatozoon mechanisms located in the oocyte membrane are activated that repel supernumerary spermatozoa (see reviews [14,39,45,75,81]). The purpose of this paper is to review what is known about the kinetics of sperm oocyte interaction in these two animal groups under natural conditions and to summarize those activation events reported to be polyspermy preventing mechanisms.…”

Section: Introductionmentioning

confidence: 99%

Polyspermy prevention: facts and artifacts?

Dale¹,

DeFelice

2010

J Assist Reprod Genet

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The purpose of this review is to open a debate as to whether or not oocytes actively repel supernumerary sperm or in nature final sperm : oocyte ratios are so low that polyspermy preventing mechanisms are not necessary. Before encountering the oocyte, spermatozoa need to be primed, either by environmental factors as in animals exhibiting external fertilization, or by factors from the female reproductive tract, as in mammals. The spermatozoon must then recognize and interact with the outer layers of the oocyte and progression of the fertilizing spermatozoon through these layers is further controlled and modulated by a precise sequence of signals in situ. Removal of these outer coats may not inhibit fertilization, however does interfere with the dynamics of sperm-oocyte interaction. We propose that monospermy in mammals and sea urchins, under natural conditions, is ensured by the controlled and gradual encounter of a minimum number of spermatozoa with the oocyte and that fine tuning is ensured by the structural and molecular organization of the oocyte and its surrounding coats. We suggest that laboratory experiments using oocytes deprived of their investments and exposed to unnaturally high concentrations of spermatozoa are artifactual and argue that the conclusions leading to the hypothesis of a fast electrical block to polyspermy are unfounded. Under laboratory conditions the majority of spermatozoa, although motile and capable of attaching to the oocyte surface, are either physiologically incompetent or attach to areas of the oocyte surface that do not support entry.

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What controls polyspermy in mammals, the oviduct or the oocyte?

Cited by 83 publications

References 158 publications

Membrane Fusions During Mammalian Fertilization

Membrane Fusions During Mammalian Fertilization

Rat recombinant β-defensin 22 is a heparin-binding protein with antimicrobial activity

Polyspermy prevention: facts and artifacts?

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