Membrane Fusion Events in Fertilization

Austin, C. R.

doi:10.1530/jrf.0.0440155

Cited by 118 publications

(36 citation statements)

References 42 publications

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“…It has been reported that only acrosome-intact mouse sperm penetrate the cumulus oophorus (a hyaluronic acid matrix with interspersed somatic cells) surrounding ovulated eggs and bind to the zona pellucida, an extracellular matrix that encircles the egg (Storey et al, 1984;Cherr et al, 1986). However, only acrosome-reacted sperm are present in the perivitelline space (between the plasma membrane of the egg and the inner aspect of the zona pellucida), and only acrosome-reacted sperm fuse with the plasma membrane of the egg to effect fertilization (Austin, 1975;Saling et al, 1979). The presence of residual acrosomal shrouds on the zona pellucida (Yanagimachi and Phillips, 1984;Cherr et al, 1986;VandeVoort et al, 1997) suggests that induction of acrosome exocytosis (acrosome reaction) occurs on the surface of the zona matrix.…”

Section: Introductionmentioning

confidence: 99%

“…Whether physiologic mobilization is initiated by G i -protein mediated ligand-receptor interactions (Ward et al, 1994), extracellular Ca 2+ influxes (Jungnickel et al, 2001), activation of internal inositol 1,4,5-triphosphate receptors (Herrick et al, 2005) or other mechanisms remains unclear. Although multiple agonists induce the acrosome reaction two-to threefold over background in vitro (Florman and Storey, 1982;Bleil and Wassarman, 1983;Meizel, 1985;Roldan et al, 1994;Shi and Roldan, 1995;Murase and Roldan, 1995;Sato et al, 2000;Son and Meizel, 2003), only binding or penetration of the zona pellucida during fertilization is 100% effective in triggering acrosome exocytosis (Austin, 1975;Saling et al, 1979;Yanagimachi, 1994).…”

Section: Introductionmentioning

confidence: 99%

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Sperm binding to the zona pellucida is not sufficient to induce acrosome exocytosis

et al. 2007

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At fertilization, spermatozoa bind to the zona pellucida (ZP1, ZP2, ZP3) surrounding ovulated mouse eggs, undergo acrosome exocytosis and penetrate the zona matrix before gamete fusion. Following fertilization, ZP2 is proteolytically cleaved and sperm no longer bind to embryos. We assessed Acr3-EGFP sperm binding to wild-type and huZP2 rescue eggs in which human ZP2 replaces mouse ZP2 but remains uncleaved after fertilization. The observed de novo binding of Acr3-EGFP sperm to embryos derived from huZP2 rescue mice supports a 'zona scaffold' model of sperm-egg recognition in which intact ZP2 dictates a three-dimensional structure supportive of sperm binding, independent of fertilization and cortical granule exocytosis. Surprisingly, the acrosomes of the bound sperm remain intact for at least 24 hours in the presence of uncleaved human ZP2 regardless of whether sperm are added before or after fertilization. The persistence of intact acrosomes indicates that sperm binding to the zona pellucida is not sufficient to induce acrosome exocytosis. A filter penetration assay suggests an alternative mechanism in which penetration into the zona matrix initiates a mechanosensory signal transduction necessary to trigger the acrosome reaction.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Sperm binding to the zona pellucida is not sufficient to induce acrosome exocytosis

et al. 2007

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“…Acrosome changes occurred rapidly and consisted of vesiculation, swelling and dispersion of the contents. These changes are similar to those taking place during the acrosome reaction, a process occurring before the fertilization of the ovum (Barros, Bedford, Franklin & Austin, 1967;Austin, 1975). The acrosome reaction involves sperm survival but similar alterations also develop in the acrosome after spermatozoa are exposed to various noxious agents (Austin, 1975).…”

Section: Discussionmentioning

confidence: 60%

“…These changes are similar to those taking place during the acrosome reaction, a process occurring before the fertilization of the ovum (Barros, Bedford, Franklin & Austin, 1967;Austin, 1975). The acrosome reaction involves sperm survival but similar alterations also develop in the acrosome after spermatozoa are exposed to various noxious agents (Austin, 1975). It is probable that the 'acrosomal reaction' observed after spermiophagy is a non-specific response to injury, presumably caused by the macrophage's lysosomal enzymes and oxidative killing mechanisms (Babior, 1978;Weiss & LoBuglio, 1982).…”

Section: Discussionmentioning

confidence: 91%

Further observations on spermiophagy by murine peritoneal macrophages in vitro

Ball¹,

Scott²,

Mitchinson³

1984

Reproduction

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Summary. Resident mouse peritoneal macrophages when maintained in cell culture phagocytosed and degraded homologous epididymal spermatozoa. The acrosome and its associated antigens were readily degraded, showing degenerative changes within minutes of spermiophagy and being completely destroyed by 1 h. Other components of the spermatozoon were more resistant and fragments of nuclear material and tail axial filaments could still be recognized within some macrophages up to 7 days after phagocytosis. The findings may be relevant to the disposal of spermatozoa in the genital tract in vivo.

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“…Immature Orgebin-Crist, 1975). It has been repeatedly suggested that changes in the macromolecular organization of the gamete membranes must precede this process of fertilization (for review, see Austin, 1975 ;Johnson, 1975).…”

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confidence: 99%