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

Baibakov, Boris; Gauthier, Lyn; Talbot, Prue; Rankin, Tracy L.; Dean, Jurrien

doi:10.1242/dev.02752

Cited by 102 publications

(104 citation statements)

References 78 publications

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“…From our perspective, any model for acrosomal exocytosis must take into account the microenvironment at the site of spermzona pellucida interaction as well as the nature of the acrosomal matrix. For example, several studies have noted that GFP loss from the acrosomes of transgenic sperm on the zona is slow and interpret this to mean that acrosomal exocytosis has not occurred (Baibakov et al, 2007, Nakanishi et al, 1999. However, we have demonstrated an intermediate of mouse acrosomal exocytosis in which GFP-transgenic mouse sperm have exposed acrosomal matrix material (as demonstrated by the binding of beads coated with anti-sp56 antibodies) but still retain GFP in their acrosomes (Kim and Gerton, 2003).…”

Section: Role Of Zp In Acrosome Interactionsmentioning

confidence: 69%

“…A recent paper published by Baibakov et al (2007) challenges some aspects of the current model for events at the interface of the sperm and the zona pellucida. They showed that transgenic mouse sperm adhering to the zona of mouse eggs retained green fluorescent protein (GFP) for an extended period of time and proposed that sperm binding is not sufficient to induce acrosome exocytosis.…”

Section: Role Of Zp In Acrosome Interactionsmentioning

confidence: 99%

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The role of the acrosomal matrix in fertilization

Buffone

Foster²,

Gerton³

2008

Int. J. Dev. Biol.

112

107

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Mammalian sperm must have properly formed acrosomes to be fully functional in the process of binding and penetrating the zona pellucida (ZP), the extracellular matrix surrounding the egg. There is much evidence to raise doubts about the old "bag of enzymes" paradigm of acrosomal function, although this is the model that seems to prevail. We concur with other scientists that acrosomal exocytosis is not an all or none event where the acrosome is either "intact" or "reacted". As determined by transmission electron microscopy of human sperm undergoing acrosomal exocytosis, six stages can be identified, with the intermediate ones involving loss of acrosomal matrix material. In the mouse, there is a temporal relationship among four stages of acrosomal exocytosis. Numerous evidences suggest a more complex role for the acrosome in fertilization in which the acrosomal matrix is a scaffold for sperm-ZP interactions that self-regulates by a controlled disassembly mechanism.

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Section: Role Of Zp In Acrosome Interactionsmentioning

confidence: 69%

Section: Role Of Zp In Acrosome Interactionsmentioning

confidence: 99%

The role of the acrosomal matrix in fertilization

Buffone

Foster²,

Gerton³

2008

Int. J. Dev. Biol.

112

107

View full text Add to dashboard Cite

show abstract

“…Despite the widely accepted idea that sperm binding to zona induces acrosome reaction, zona-binding spermatozoa had intact acrosome and did not acrosome react by binding to zona [4,41]. This was reinforced by a recent study observing the fertilization process in vitro using spermatozoa having acrosomal GFP.…”

Section: Zona-induced Acrosome Reaction Must Be Reconsideredmentioning

confidence: 99%

Mechanism of Fertilization: A Modern View

Okabe

2014

Exp. Anim.

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Despite numerous studies on mammalian fertilization, the mechanisms of fertilizationincluding the timing of acrosome reaction-remain largely unknown; more accurately described, the classical theory built upon years of layered experimental data is being challenged by recent conflicting evidence provided by gene-manipulated animals. Although in vitro fertilization remains our central research tool, the classical theory's decline reminds us of the importance of in vivo observations. Here, I describe the essential roles of gene-manipulated animals in elucidating the mechanism of fertilization and the pitfalls of in vitro fertilization studies trapping many researchers.

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“…A primary functional assay is the human zona-binding test. Whilst the paradigm of sperm binding and subsequent acrosome reaction may be questioned in mice, 24 consistently, robust clinical data demonstrates its usefulness for ART success. A large range of patients have been identified with poor or adequate binding but minimal induction of the acrosome reaction in response to the zona.…”

Section: Sperm Dysfunction-old Tests Lying Dormant?mentioning

confidence: 99%

Diagnostic tools in male infertility—the question of sperm dysfunction

Barratt¹,

Mansell²,

Beaton³

et al. 2010

Asian J Androl

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Sperm dysfunction is the single most common cause of infertility, yet what is remarkable is that, there is no drug a man can take or add to his spermatozoa in vitro to improve fertility. One reason for the lack of progress in this area is that our understanding of the cellular and molecular workings of the mature spermatazoon is limited. However, over the last few years there has been considerable progress in our knowledge base and in addressing new methods to diagnose sperm dysfunction. We review the current state of the field and provide insights for further development. We conclude that: (i) there is little to be gained from more studies identifying/categorizing various populations of men using a basic semen assessment, where an effort is required in making sure the analysis is performed in an appropriate high quality way; (ii) technological development is likely to bring the reality of sperm function testing closer to implementation into the clinical pathways. In doing this, these assays must be robust, cheap (or more appropriately termed cost effective), easy to use and clinically useful; and (iii) clinical necessity, e.g., the need to identify the highest quality spermatozoon for injection is driving basic research forward. This is an exciting time to be an andrologist and, likely, a fruitful one. Keywords: gamete biomarker; male fertility; sperm biomarker; sperm dysfunction INTRODUCTION Infertility is a significant global problem affecting approximately 80 million (1:7) couples worldwide. 1 In a landmark study by Mike Hull and colleagues, in which a representative British population was studied, sperm dysfunction (lacking 'normal' function) was identified as the single most common cause of infertility. 2 Subsequent studies have confirmed these observations 3 and highlighted dysfunctional cells in men with 'normal' semen parameters and conversely normal sperm function in oligozoospermic men. 4 What is remarkable is that, for this group, there is no drug a man can take or add to his spermatozoa in vitro to improve fertility. The only option is assisted reproductive technology (ART) which usually consists of a graduation of treatment depending on severity, i.e., intrauterine insemination for mild, in vitro fertilisation (IVF) for moderate and intracytoplasmic sperm injection (ICSI) for men with severe sperm dysfunction. One reason for the lack of progress in this area is that our understanding of the cellular and molecular workings of the mature spermatazoon is limited. However, over the last few years there has been considerable progress in our knowledge base and in addressing new methods to diagnose sperm dysfunction. The purpose of this paper is to review the current state of the field and provide insights for further development. The initial focus is on the value of semen analysis as a clinical tool with the discussion progressing to examining sperm dysfunction in detail.

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

Cited by 102 publications

References 78 publications

The role of the acrosomal matrix in fertilization

The role of the acrosomal matrix in fertilization

Mechanism of Fertilization: A Modern View

Diagnostic tools in male infertility—the question of sperm dysfunction

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