Low proportions of sperm can bind to the zona pellucida of human oocytes

Liu, D.Y.; Garrett, Claire; Baker, H. W. G.

doi:10.1093/humrep/deg456

Cited by 62 publications

(51 citation statements)

References 30 publications

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“…For example, Jouannet et al [22] did not use that classification 'strict criteria' at all. Liu et al [26] also fall into the same group, and they wrote that 'Normal sperm morphology (zona pellucida-bound, %)' was the same in the fertile and infertile groups (60% vs. 54%; not significantly different). Menkveld et al [24] came to the following conclusion: 'For sperm morphology evaluated according to WHO criteria (1992-traditional method), the best cut-off point to identify the males with a possible subfertility problem based on the results of the fertile and subfertile populations investigated in this study was ≤ 30% morphologically normal spermatozoa with a sensitivity and specificity of 74.5% and 76.6%, respectively.…”

Section: Morphology Of Spermatozoamentioning

confidence: 97%

“…These facts ought to be viewed in the light of the claims that the 'Tygerberg strict criteria' are supported by a 'myriad of publications' (e.g., [20]). Section 2.13.2 of the new WHO manual [6] states, 'By the strict application of certain criteria of sperm morphology, relationships between the percentage of normal forms and various fertility endpoints (TTP, pregnancy rates in vivo and in vitro) have been established (Eggert-Kruse et al [21]; Jouannet et al [22]; Coetzee et al [18]; Toner et al [23]; Menkveld et al [24]; Van Waart et al [19]; Garrett et al [25]; Liu et al [26]) that may be useful for the prognosis of fertility'. Hopefully these authors used 'strict application of (their own) criteria', but that is not to be confused with the application of 'strict criteria'.…”

Section: Morphology Of Spermatozoamentioning

confidence: 99%

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Semen analysis with regard to sperm number, sperm morphology and functional aspects

Eliasson¹

2010

Asian J Androl

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The new World Health Organization (WHO) Manual for Semen Analysis contains several improvements. One is that the 20 million spermatozoa per mL paradigm has been ousted in favour of proper calculations of lower reference limits for semen from men, whose partners had a time-to-pregnancy of 12 months or less. The recommendation to grade the progressive motility as described in the third and fourth editions of the WHO manual was not evidence-based, and WHO was therefore motivated to abandon it. However, the new recommendation is not evidence-based either, and it is difficult to understand the rational for the new assessment. It may have been a compromise to avoid returning to the rather robust system recommended in the first edition (1980). The unconditional recommendation of the 'Tygerberg strict criteria' is not evidence-based, and seems to be the result of an unfortunate bias in the composition of the Committee in favour of individuals known to support the 'strict criteria' method. This recommendation will have negative effects on the development of andrology as a scientific field. Given the importance of the WHO manual, it is unfortunate that the recommendations for such important variables, as motility and morphology, lack evidence-based support.

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Section: Morphology Of Spermatozoamentioning

confidence: 97%

Section: Morphology Of Spermatozoamentioning

confidence: 99%

Semen analysis with regard to sperm number, sperm morphology and functional aspects

Eliasson¹

2010

Asian J Androl

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“…[10][11][12][13] For conventional IVF, it is adequate to inseminate oocytes using motile sperm selected by these methods since the sperm which fertilizes will be further selected through the biological process of spermoocyte interaction, especially sperm-ZP binding. [14][15][16][17] In contrast with conventional ICSI, this additional selection does not occur. The embryologists subjectively select a sperm based only on motility and gross morphology and it is very difficult to select a most competent sperm for injection of an oocyte, in particular for samples with high proportion of DNA damaged sperm.…”

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confidence: 99%

“…20 In human ejaculate from fertile men, although an average ejaculate contains 100-200 million motile sperm, only about 14% motile sperm are capable of binding to the human ZP in vitro. 16 Therefore, there is a very small proportion of motile sperm in human ejaculate that has the capacity of binding to the ZP. Clearly, only those sperm bound to the ZP have a chance to penetrate the ZP and then fertilize the oocyte either in vivo or IVF conditions.…”

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confidence: 99%

“…Although the ability of sperm binding to the ZP is not necessary and likely only a viable sperm with normal DNA is needed for fertilization with ICSI, many previous studies showed clearly that the human ZP selectively binds sperm with normal morphology. [14][15][16][17] The majority of sperm (average .92%) bound to the ZP have normal nuclear chromatin DNA. 17 These results suggest that the human ZP possesses the capacity to select normal functioning sperm and therefore, the ZP-bound sperm should have a superior quality compared to the general population of motile sperm in medium or scientist subjectively selected motile sperm during conventional ICSI.…”

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confidence: 99%

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Could using the zona pellucida bound sperm for intracytoplasmic sperm injection (ICSI) enhance the outcome of ICSI?

Liu¹

2011

Asian J Androl

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I n the recent literature, several interesting articles have been published using the zona pellucdia (ZP)-bound sperm for intracytoplasmic sperm injection (ICSI) to enhance embryo quality, implantation and clinical pregnancy rates. [1][2][3] The three studies were performed independently in different ART clinics. In the test group, patients' sibling immature (either germinal vesicle (GV) or metaphase I) oocytes were used to harvest the ZP-bound sperm, which were used for injection of mature oocytes. In the control group, ICSI patients with similar female age and sperm profiles had ICSI with standard sperm selection by the embryologist subjectively choosing the sperm. 2,3 The results showed that the proportion of high-quality embryos (grades 1 and 2) and implantation rates were higher with ICSI using ZP-bound sperm than with conventional sperm selection. More pregnancies were achieved in the ZP-bound sperm group although clinical (fetal heart detected) pregnancy rates did not reach statistical significance between the two groups, likely due to small sample sizes. These preliminary reports suggest that ZPselected sperm appear to be superior to subjectively selected sperm for ICSI. If this finding can be further verified by a large clinical study, the use of the ZP-bound sperm for ICSI could be applied more widely in ICSI to enhance pregnancy outcome.In the literature, some studies have been reported that in vitro fertilization (IVF) embryos produced relatively higher implantation and clinical pregnancy rates compared to ICSI embryos. 4,5 It is possible that some ICSI patients with low implantation or pregnancy may result from injection of inadequate or poor-quality sperm, for example, with abnormal morphological or DNA damaged sperm. [6][7][8][9] As the majority of ICSI patients are male factor infertility and they have variable abnormal ejaculated sperm, particularly those with high proportion of DNA damaged sperm, subjective manual method is inconsistent or unable to select a most competent sperm for ICSI. Thus it is necessary to develop an objective and efficient method for selection of the most competent sperm for ICSI.Over the many years since ICSI was first introduced in 1992, ICSI has been using the same sperm preparation methods as conventional IVF, such as swim-up or discontinuous density gradients centrifugation. These classic methods are predominately designed to harvest large numbers of motile sperm and to eliminate non-sperm cells and debris. However, these sperm preparation methods are less or not effective in the selection of sperm with normal morphology and normal DNA. [10][11][12][13] For conventional IVF, it is adequate to inseminate oocytes using motile sperm selected by these methods since the sperm which fertilizes will be further selected through the biological process of spermoocyte interaction, especially sperm-ZP binding. [14][15][16][17] In contrast with conventional ICSI, this additional selection does not occur. The embryologists subjectively select a sperm based only on motility and gr...

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Relevance of glycosylation of human zona pellucida glycoproteins for their binding to capacitated human spermatozoa and subsequent induction of acrosomal exocytosis

Chakravarty

Kadunganattil

Bansal

et al. 2007

Molecular Reproduction Devel

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To delineate the functional aspects of zona pellucida (ZP) glycoproteins during fertilization in human, in the present study, fluorochrome-conjugated Escherichia coli (E. coli)- and baculovirus-expressed recombinant human ZP glycoprotein-2 (ZP2), -3 (ZP3), and -4 (ZP4) were employed. In an immunofluorescence assay, capacitated human sperm exhibited binding of the baculovirus-expressed recombinant ZP3 as well as ZP4 to either acrosomal cap or equatorial region whereas acrosome-reacted sperm failed to show any binding to the acrosomal cap. Using double labeling experiments, simultaneous binding of ZP3 and ZP4 to the acrosomal cap was observed suggesting the possibility of different binding sites of these proteins on the sperm surface. No binding of ZP2 was observed to the capacitated sperm. However, acrosome-reacted sperm (20.00 +/- 1.93%) showed binding of ZP2 that was restricted to only equatorial region. Interestingly, E. coli-expressed recombinant human zona proteins also showed very similar binding profiles. Competitive inhibition studies with unlabeled recombinant human zona proteins revealed the specificity of the above binding characteristics. Binding characteristics have been further validated by an indirect immunofluorescence assay using native human heat solubilized isolated zona pellucida. Employing baculovirus-expressed recombinant ZP3 and ZP4 with reduced N-linked glycosylation and respective E. coli-expressed recombinant proteins, it was observed that glycosylation is required for induction of acrosomal exocytosis but its absence may not compromise on their binding ability. These studies have revealed the binding profile of individual human zona protein to spermatozoa and further strengthened the importance of glycosylation of zona proteins for acrosomal exocytosis in spermatozoa.

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Low proportions of sperm can bind to the zona pellucida of human oocytes

Abstract: More than 75% of motile sperm from fertile men have no ability to bind to the ZP. This finding has important implications for improvement of semen analysis.

Cited by 62 publications

References 30 publications

Semen analysis with regard to sperm number, sperm morphology and functional aspects

Semen analysis with regard to sperm number, sperm morphology and functional aspects

Could using the zona pellucida bound sperm for intracytoplasmic sperm injection (ICSI) enhance the outcome of ICSI?

Relevance of glycosylation of human zona pellucida glycoproteins for their binding to capacitated human spermatozoa and subsequent induction of acrosomal exocytosis

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