Clinical importance of zona pellucida-induced acrosome reaction and its predictive value for IVF

Human sperm acrosome function assays are predictive of fertilization rate in vitro: a retrospective cohort study and meta-analysis

OBJECTIVE

To determine whether acrosome function scoring-including acrosomal enzyme (AE) levels and acrosome reaction (AR) results-can predict fertilization rate in vitro.

METHODS

We examined the predictive value of acrosomal enzymes (AE) determined by spectrophotometry/N-α-benzoyl-DL-arginine-p-nitroanilide for fertilization rate (FR) in vitro in a retrospective cohort study of 737 infertile couples undergoing IVF therapy. Additionally, a meta-analysis was done for prospective cohort or case-control studies; the following summary measures were reported to expand upon the findings: pooled spearman correlation coefficient (Rs), standardized mean difference (SMD), sensitivity (SEN), specificity (SPE), positive likelihood ratio (PLR), negative likelihood ratio (NLR), diagnostic score (DS), diagnostic odds ratio (DOR), and area under the summary receiver operating characteristic curve (AUC).

RESULTS

Lower AE levels determined by spectrophotometry with a cut-off value of <25μIU/10⁶ spermatozoa were predictive of total fertilization failure (TFF) with moderate SEN (88.23%) and low SPE (16.50%). On meta-analysis, a total of 44 unique articles were selected, but given the multiple techniques described there was a total of 67 total datasets extracted from these 44 articles, comprising 5356 infertile couples undergoing IVF therapy. The AE levels or induced AR% was positively correlated with FR (Rs = 0.38, SMD = 0.79; Rs = 0.40, SMD = 0.86, respectively). Lower AE levels or induced AR% was predictive of lower fertilization rate with moderate accuracy (AUC = 0.78, AUC = 0.84, respectively); this was accompanied by low SEN/moderate SPE (0.57/0.85), moderate SEN/moderate SPE (0.79/0.87), respectively. For AE assay, the diagnostic performance in Asia (Rs = 0.24, SMD = 0.50) was inferior to that in North America (Rs = 0.54, SMD = 0.81) and Europe (Rs = 0.46, SMD = 0.92). Cryopreserved spermatozoa (SMD = 0.20, P = 0.204) were inferior to fresh spermatozoa (SMD = 0.89, P <  0.001). Sperm preparation yielded inferior results as compared to no preparation; spermatozoa after swim up were weak relevant (Rs = 0.27, P = 0.044); and there was no correlation for spermatozoa after a discontinuous gradient (SMD = 1.07, P >  0.05). Lower AE levels determined by fluorometry or substrate assay were used for predicting lower FR with low sensitivity and high specificity; the spectrophotometry assay had an uncertain predictive value. For induced AR assay, the diagnostic performance in the other areas was inferior to that in Africa (Rs = 0.65, SMD = 1.86). No preparation or double preparation yielded inferior results as compared to one preparation (Rs = 0.41); discontinuous gradient (Rs = 0.17, SMD = 0.47) was inferior to swim up (Rs =0.65, SMD = 1.51). Nonphysiological triggers (SMD = 0.81) did not differ from physiological triggers (SMD = 0.95) in general; ZP (Rs = 0.63) or mannose (Rs = 0.59) was superior to other physiological or nonphysiological triggers; and there was no correlation for human follicle fluid, progesterone, cyclic adenosine 3'-5'-phosphate analogue and phorbol ester-BSA-GlcNAc Neoglycoproteins with N-acetylglucosamine residues. Lower induced AR% determined by indirect immunofluorescence, direct immunofluorescence with lection, or triple stain was used for predicting lower FR, with moderate sensitivity/high specificity, moderate sensitivity/high specificity, or high sensitivity/low specificity.

CONCLUSIONS

Although the correlation between acrosome function scoring and FR was significant, the assays were neither highly sensitive nor specific. Additionally, the diagnostic performance showed regional effects as well as an effect of the sperm preparation or assay method. More studies of multicenter, large-scale, careful design and synthesizing multiple sperm functional assays and oocyte quality assays are still needed in clinical settings to better predict fertilization outcome in IVF.

How accurate is sperm morphology as an indicator of sperm function?

Sperm morphology has been consistently correlated with fertilisation success or failure. The clinical relevance of the percentage normal spermatozoa has been a widely discussed topic amongst infertility specialists and scientists. This study aimed to evaluate the role of sperm morphology as an indicator of additional sperm functions among 114 andrology referrals. The sperm functions that were investigated included chromatin packaging quality (CMA3 test (n = 109), zona-induced acrosome reaction (ZIAR test; n = 36), hemizona assay (HZI; n = 36) and progressive motility (n = 47). Chromatin packaging quality had a negative and significant (P = 0.0001, r = -0.74) correlation with the percentage normal spermatozoa, while progressive motility had a significant and positive correlation (P = 0.0001, 0.59). Accurate sperm morphology scoring as described by the WHO 2010 manual can therefore be used as an indicator of specific sperm functions.

The molecular chaperone HSPA2 plays a key role in regulating the expression of sperm surface receptors that mediate sperm-egg recognition

A common defect encountered in the spermatozoa of male infertility patients is an idiopathic failure of sperm–egg recognition. In order to resolve the molecular basis of this condition we have compared the proteomic profiles of spermatozoa exhibiting an impaired capacity for sperm-egg recognition with normal cells using label free mass spectrometry (MS)-based quantification. This analysis indicated that impaired sperm–zona binding was associated with reduced expression of the molecular chaperone, heat shock 70 kDa protein 2 (HSPA2), from the sperm proteome. Western blot analysis confirmed this observation in independent patients and demonstrated that the defect did not extend to other members of the HSP70 family. HSPA2 was present in the acrosomal domain of human spermatozoa as a major component of 5 large molecular mass complexes, the most dominant of which was found to contain HSPA2 in close association with just two other proteins, sperm adhesion molecule 1 (SPAM1) and arylsulfatase A (ARSA), both of which that have previously been implicated in sperm-egg interaction. The interaction between SPAM1, ARSA and HSPA2 in a multimeric complex mediating sperm-egg interaction, coupled with the complete failure of this process when HSPA2 is depleted in infertile patients, provides new insights into the mechanisms by which sperm function is impaired in cases of male infertility.

Zona pellucida-induced acrosome reaction in human spermatozoa is potentiated by glycodelin-A via down-regulation of extracellular signal-regulated kinases and up-regulation of zona pellucida-induced calcium influx

BACKGROUND

Glycodelin-A interacts with spermatozoa before fertilization, but its role in modulating sperm functions is not known. Zona pellucida-induced acrosome reaction is crucial to fertilization and its dysfunction is a cause of male infertility. We hypothesized that glycodelin-A, a glycoprotein found in the female reproductive tract, potentiates human spermatozoa for zona pellucida-induced acrosome reaction.

METHODS

Glycodelin isoforms were immunoaffinity purified. The sperm intracellular cAMP concentration, protein kinase-A (PKA) and extracellular signal-regulated kinase (ERK) activities, and intracellular calcium were measured by ELISA, kinase activity assay kits and Fluo-4AM technique, respectively. The phosphorylation of inositol 1,4,5-trisphosphate type-1 receptor (IP3R1) mediated by ERK was determined by western blotting. Zona pellucida-induced acrosome reaction was detected by Pisum sativum staining.

RESULTS

Pretreatment of spermatozoa with glycodelin-A significantly up-regulated adenylyl cyclase/PKA activity and down-regulated the activity of ERK and its phosphorylation of IP3R1, thereby enhancing zona pellucida-induced calcium influx and zona pellucida-induced acrosome reaction. Glycodelin-F or deglycosylated glycodelin-A did not have these actions. Treatment of spermatozoa with a protein kinase inhibitor abolished the priming activity of glycodelin-A, whilst ERK pathway inhibitors mimic the stimulatory effect of glycodelin-A on zona pellucida-induced acrosome reaction.

CONCLUSIONS

Glycodelin-A in the female reproductive tract sensitizes spermatozoa for zona pellucida-induced acrosome reaction in a glycosylation-specific manner through activation of the adenylyl cyclase/PKA pathway, suppression of extracellular signal-regulated kinase activation and up-regulation of zona pellucida-induced calcium influx. The action of glycodelin-A may be important in vivo to ensure full responsiveness of human spermatozoa to the zona pellucida.

New insights into the mechanisms of fertilization: comparison of the fertilization steps, composition, and structure of the zona pellucida between horses and pigs

The mechanism of fertilization remains largely enigmatic in mammals. Most studies exploring the molecular mechanism underlying fertilization have been restricted to a single species, generally the mouse, without a comparative approach. However, the identification of divergences between species could allow us to highlight key components in the mechanism of fertilization. In the pig, in vitro fertilization (IVF) and polyspermy rates are high, and spermatozoa penetrate easily through the zona pellucida (ZP). In contrast, IVF rates are low in the horse, and polyspermy is scarce. Our objective was to develop a comparative strategy between these two divergent models. First, we compared the role of equine and porcine gametes in the following five functions using intraspecific and interspecific IVF: ZP binding, acrosome reaction, penetration through the ZP, gamete fusion, and pronucleus formation. Under in vitro conditions, we showed that the ZP is a determining element in sperm-ZP attachment and penetration, whereas the capacity of the spermatozoa is of less importance. In contrast, the capacity of the spermatozoa is a key component of the acrosome reaction step. Second, we compared the composition and structure of the equine and porcine ZP. We observed differences in the number and localization of the ZP glycoproteins and in the mesh-like structure of the ZP between equine and porcine species. These differences might correlate with the differences in spermatozoal attachment and penetration rates. In conclusion, our comparative approach allows us to identify determining elements in the mechanism of fertilization.

Relationship between seminal plasma zinc concentration and spermatozoa-zona pellucida binding and the ZP-induced acrosome reaction in subfertile men

The aim of this study was to determine the relationship between seminal zinc concentration and spermatozoa-zona pellucida (ZP) binding and the ZP-induced acrosome reaction (ZPIAR) in subfertile men. Semen analyses and seminal zinc concentration assessments were carried out according to the World Health Organization manual for 458 subfertile men. A spermatozoa-ZP interaction test was carried out by incubating 2 x 10(6) motile spermatozoa with a group of four unfertilized oocytes obtained from a clinical in vitro fertilization programme. After 2 h of incubation, the number of spermatozoa bound per ZP and the ZPIAR of ZP-bound spermatozoa were examined. The effect of adding 0.5 mmol L(-1) zinc to the media on the ZPIAR of spermatozoa from normozoospermic men was also tested in vitro. Seminal zinc concentration positively correlated with sperm count and duration of abstinence, but negatively correlated with semen volume. On analysis of data from all participants, both spermatozoa-ZP binding and the ZPIAR were significantly correlated with sperm motility and normal morphology, but not with seminal zinc concentration. However, in men with normozoospermic semen, the seminal zinc concentration was significantly higher in men with defective ZPIAR (< 16%) than in those with normal ZPIAR (>or= 16%) (P < 0.01). The addition of 0.5 mmol L(-1) zinc to the culture media had no effect on spermatozoa-ZP binding, but significantly reduced the ZPIAR in vitro (P < 0.001). In conclusion, seminal zinc concentration is correlated with sperm count and the duration of abstinence in subfertile men. In men with normozoospermic semen, high seminal zinc concentration may have an adverse effect on the ZPIAR.

The influence of homogenous zona pellucida on human spermatozoa hyperactivation, acrosome reaction and zona binding

The study aimed to evaluate the changes in sperm motion characteristics and the occurrence of hyperactivation among sperm populations after exposure to human zona pellucida. Motile spermatozoa samples were used to evaluate the sperm-zona binding capacity, zona-induced acrosome reaction and changes in sperm motion characteristics. Sperm motion characteristic changes studied included straight line velocity, curvilinear velocity, amplitude of lateral head displacement, straightness and beat cross frequency. Recordings were performed on semen immediately after liquefaction, 3 h capacitation and after exposure to solubilised human zona pellucida. The semen samples were divided into morphology categories, namely six (16 +/- 1.4% normal forms, normal patterns), 31 (8 +/- 1.7% normal forms, G-pattern) and 27 (3 +/- 1.3% normal forms, P-pattern). The Hemizona Indices for the three morphology groups namely normal, G-patterns and P-patterns, were 77 +/- 6%, 61 +/- 5% and 41 +/- 5% respectively (P <or= 0.05). The zona-induced acrosome reaction for the three groups were 25.0 +/- 2% (normal group), 18.0 +/- 2% (G-patterns) and 14.1 +/- 0.6% (P-pattern) (P <or= 0.05). The number of hyperactivated sperm showed an increase in the ejaculates (1%), after capacitation (2%) and exposure to zona pellucida (5%) (P <or= 0.05). When divided into the three morphology groups, the number of spermatozoa with hyperactivated motility was more profound in men with normal morphology compared with G- and P-pattern men. Human zona pellucida is a strong inducer of hyperactivated motility among spermatozoa and the effect is more profound among sperm populations with normal morphology.

Biological Effects of Recombinant Human Zona Pellucida Proteins on Sperm Function1

The initial interaction between gametes takes place at the level of the sperm surface and the zona pellucida (ZP), the extracellular matrix of the egg in mammals. Successful fertilization requires the proper molecular recognition of the ZP by the sperm. Recently, human ZP was demonstrated to be composed of four proteins: ZP1, ZP2, ZP3, and ZP4. The goals of this study were to determine the effects of recombinant human ZP2, ZP3, and ZP4 on human sperm acrosomal exocytosis and sperm motility. Exposure of sperm to ZP proteins, alone or in combination, promoted acrosomal exocytosis in a time-dependent manner. This effect occurred in parallel with a considerable decrease in progressive motility, coincident with an increase in nonprogressive sperm motility. An analysis of kinetic parameters of ZP-treated sperm demonstrated that a characteristic motility pattern could be defined by values of curvilinear velocity > 63.9 mum/s and linearity <or= 15.5%. A strong correlation between curvilinear velocity and the amplitude of lateral head displacement was also observed. The incidence of sperm having these particular kinetic parameters increased after exposure to ZP proteins. These studies of two processes involved in sperm penetration through the ZP confirm that zona glycoproteins promote acrosomal exocytosis and now establish an additional role for these components as modifiers of sperm motility.

Predictive value of selected sperm parameters for classical in vitro fertilization procedure of oocyte fertilization

A proportion of fertilized oocytes during classical in vitro fertilization (IVF) procedure was analysed depending on the following factors: number of mature oocytes, seminological criteria such as sperm morphology in raw semen and after its selection in a density gradient (six structural defects of a male gamete were taken into consideration), sperm concentration, motility parameters according to World Health Organization criteria and the functional tests: hypo-osmotic swelling assay and acrosomal reaction induced by calcium ionophore. Evaluation of DNA content in sperm by image cytometry and determination of malonyldialdehydes in seminal plasma were also performed. Seventy-nine semen samples from patients undergoing IVF were assessed. Apart from significant correlations obtained for selected semen parameters and proportion of fertilized eggs, logistic regression analysis showed that the best predictive factors for oocyte fertilization were normal morphology of sperm before and after gradient selection, grade B and C of sperm movement in raw semen, and DNA content after density gradient centrifugation, which all accounted for 76.7% of fertilization predictive value.

Clinical application of sperm-oocyte interaction tests in in vitro fertilization--embryo transfer and intracytoplasmic sperm injection programs

OBJECTIVE

To review the clinical value of sperm-oocyte interaction tests for the diagnosis and management of infertility by standard IVF or intracytoplasmic sperm injection (ICSI).

DESIGN

Review of recent publications on relationships among sperm-oocyte interaction tests, sperm characteristics, and results of IVF and determination of frequency of defective sperm-oocyte interaction in infertile men.

MAIN OUTCOME MEASURE(S)

Fertilization rates with IVF, sperm characteristics, sperm-zona pellucida (ZP) binding, ZP-induced acrosome reaction (AR), and sperm-ZP penetration.

RESULT(S)

Sperm defects associated with low sperm-ZP binding or impaired ZP-induced AR and sperm-ZP penetration are the major causes of failure of fertilization when all or most oocytes from a couple do not fertilize in standard IVF. There is a high frequency of defective sperm-ZP interaction in men with oligozoospermia (<20 x 10(6)/mL) and severe teratozoospermia (strict normal sperm morphology < or =5%). Sperm morphology correlates with sperm-ZP binding, and sperm concentration correlates with ZP-induced AR in infertile men with sperm concentrations >20 x 10(6)/mL. Defective ZP-induced AR may cause infertility in up to 25% men with idiopathic infertility. These patients require ICSI despite the normal standard semen analyses.

CONCLUSION(S)

Sperm-oocyte interaction tests are useful for diagnosis of subtle sperm defects that cause infertility in men without severe abnormalities of semen analysis. Pre-IVF diagnosis of these sperm defects will assist in the clinical assignment of patients to treatment with either standard IVF or ICSI.

Present concept of unexplained infertility

Despite improvements in both diagnostic assessment and treatment of infertile couples, many couples still have no explanation for their infertility. Unexplained infertility (the failure to conceive of a couple in whom no definitive cause for infertility can be found) has an incidence of 10-20% in all infertile couples. The incidence varies with the population studied and with the criteria used. Unexplained infertility is not an absolute condition but rather a relative inability to conceive, and many of these couples may conceive without treatment. The treatment options for unexplained infertility are several and the treatment results are promising. Expectant management can be recommended if the woman is under 28-30 years of age and the infertility duration is less than 2-3 years. In vitro fertilization (IVF) has revolutionized the treatment of infertile couples, as well as profoundly increasing the basic understanding of human reproduction. IVF can be used as both a diagnostic and a therapeutic tool in couples with unexplained infertility. The pregnancy rates with IVF are good, at 40% per treatment cycle. In addition, the outcome of pregnancies among women with unexplained infertility is generally comparable to that of spontaneous and other pregnancies using assisted reproductive technologies.

Relationship between human sperm morphology and acrosomal function

PURPOSE

In this study, we investigated the relationship between functionality of the acrosome and sperm morphology.

METHODS

Acrosome reaction (AR) was separately determined in live and dead sperm and in those with normal, small, and large sized acrosomes by means of the triple stain. Morphology was analyzed according to strict criteria after Papanicolaou stain.

RESULTS

AR and morphology correlated regarding detection of large and small sized acrosomes, but not for normal sized acrosomes. Spontaneous AR was significantly influenced by acrosomal size. Sperm with large (11.4%) and normal (9.2%) acrosomes exhibited a significantly higher percentage of life spontaneously acrosome-reacted sperm than those with small acrosomes (4.5%). Sperm with small acrosomes were associated with a higher percentage of cell death.

CONCLUSION

The results indicate that sperm with small acrosomes are more susceptible to cell death and nonphysiological acrosomal loss. Acrosome size reflects the physiological capability of sperm function and therefore male fertility potential.

Normal range and variation of the zona pellucida-induced acrosome reaction in fertile men

OBJECTIVE

To investigate the normal range of the zona pellucida (ZP)-induced acrosome reaction (AR) in fertile men.

DESIGN

A study of normative data.

SETTING

Academic research and teaching tertiary hospital.None.Fertile men (n = 111) who had children or whose female partner was currently pregnant. MAIN OUTCOME MEASURE (S): Semen analysis, sperm-ZP binding, and the ZP-induced AR.

RESULT(S)

There was wide range for the ZP-induced AR: 20%-98% with a mean of 48%. The ZP-induced AR was significantly correlated with sperm concentration and normal morphology. The ZP-induced AR was significantly lower in men with sperm concentration <or=60 x 10(6)/mL than those with sperm concentration >60 x 10(6)/mL. Similarly, men with normal sperm morphology >or=15% had significantly higher ZP-induced AR than men with normal morphology <15%.

CONCLUSION(S)

There is a wide range of the ZP-induced AR in fertile men that is correlated with sperm concentration and normal morphology.

Failed fertilization: is it predictable?

PURPOSE OF REVIEW

The purpose of this review is to critically examine the ability of screening tests to predict fertilization failure.

RECENT FINDINGS

Failed fertilization occurs in 5-10% of in-vitro fertilization cycles and 2-3% of intracytoplasmic sperm injection cycles. Failed fertilization may result from impaired spermatozoa, oocyte deficiencies or defects in the in-vitro sperm/oocyte medium. In the in-vitro fertilization setting most cases are caused by male factor deficiencies, whereas failure of oocyte activation is the most common cause of failed fertilization after intracytoplasmic sperm injection. Although the standard semen analysis has limited ability to predict fertilization failure, strict sperm morphology criteria, sperm-zona binding ratios and zona pellucida induced acrosome reaction tests provide increased capacity to avoid this outcome. The quality of the semen sample on the day of oocyte retrieval and fertilization performance in previous in-vitro fertilization cycles may also guide the appropriate use of intracytoplasmic sperm injection. However, the routine use of the latter technique in cases of non-male factor infertility is contraindicated.

SUMMARY

The ever improving techniques highlighted in this analysis offer improved ability to predict failed fertilization.

Relationship between zona pellucida-induced acrosome reaction, sperm morphology, sperm-zona pellucida binding, and in vitro fertilization

OBJECTIVE

To evaluate the possible relationships between sperm morphology, acrosome responsiveness to solubilized human zona pellucida, and sperm-zona binding potential among [1] consecutive andrology referrals and [2] randomly selected in vitro fertilization (IVF) cases.

DESIGN

Prospective analytical study.

SETTING

Academic training hospital.Randomly selected couples consulting for infertility.

INTERVENTION(S)

Acrosome reaction response to solubilized human zona pellucida was recorded.

MAIN OUTCOME MEASURE(S)

We determined the difference in the percentage of sperm that acrosome reacted after exposure to solubilized zona pellucida and spontaneous acrosome reaction. The results were expressed as percentage zona induced acrosome reaction (ZIAR).

RESULT(S)

Data were analyzed using correlation coefficients (r) and receiver operator characteristics (ROC curve analyses). The ROC curve analyses indicated ZIAR to be a sensitive indicator for fertilization failure during IVF therapy, with sensitivity and specificity of 81% and 75%, respectively. For andrology referrals, a positive and statistically significant correlation existed between ZIAR data and sperm morphology (r = 0.65) and sperm-zona binding (r = 0.57).

CONCLUSION(S)

ZIAR results provide further information regarding dysfunctional sperm and can be used as an additional diagnostic test. Our results predicted fertilization failure during IVF treatment.

Disordered zona pellucida-induced acrosome reaction and failure of in vitro fertilization in patients with unexplained infertility

OBJECTIVE

To determine the relationship between the zona pellucida (ZP)-induced acrosome reaction (AR) and fertilization rate and pregnancy rate in standard IVF and the frequency of disordered ZP-induced AR (DZPIAR) in patients with unexplained infertility.

DESIGN

Prospective study.

SETTING

Academic research and teaching tertiary hospital.

PATIENTS

Patients with unexplained infertility with normal semen analysis.

INTERVENTION

None.

MAIN OUTCOME MEASURE

Semen analysis, the ZP-induced AR, and measurements of fertilization rate and pregnancy rate with in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI).

RESULT(S)

A statistically significant correlation was found for the ZP-induced AR and fertilization rate with standard IVF (n = 65). Patients with DZPIAR (ZP-induced AR of <or=16%) had an average fertilization rate of 23%, in contrast to patients with ZP-induced AR of >16%, who had an average fertilization rate of 61%. The sensitivity and specificity of DZPIAR for prediction of IVF rates <30% and >or=30% were 80% and 86%, respectively. Of 260 patients screened, the frequency of DZPIAR was 29%. Ten patients with DZPIAR had an average fertilization rate of 15% and no pregnancy with initial IVF cycles, and a fertilization rate of 61% (with three live-birth pregnancies) with subsequent ICSI cycles. Another 33 patients with DZPIAR were treated with ICSI alone, with an average fertilization rate of 71% and a live-birth pregnancy rate of 17% per embryo transfer. Sixteen of the patients had live-birth pregnancies (including one set of twins) after undergoing an average of 3.2 embryo transfers.

CONCLUSION(S)

Patients with DZPIAR have a low or zero fertilization rate with standard IVF but high fertilization and pregnancy rates with ICSI. Up to 29% of patients with unexplained infertility with normal semen analysis may have this condition, which should be diagnosed and treated with ICSI rather then standard IVF.

Physiological and proteomic approaches to studying prefertilization events in the human

This research aims firstly to understand, in cellular and molecular terms, how a mature human spermatozoon is prepared for fertilization, and secondly, to identify what factors are involved in the initial signalling interactions between the egg and spermatozoon. In order to achieve these objectives, a combination of approaches is being used, including single-cell imaging, patch clamping and proteomics. Single-cell imaging reveals hidden complexity and heterogeneity in signalling responses in spermatozoa. Characterization of cell physiology at the single-cell level must be a future aim, including the study of ion channel expression and function by patch clamping. Proteomic experiments are aimed at identifying defects in protein expression in specific subgroups of men, e.g. those with globozoospermia. A better understanding of prefertilization events will allow the development of non-assisted reproductive therapy, drug-based treatments for male infertility.

Pathophysiology of oligoasthenoteratozoo-spermia: are we improving in the diagnosis?

Male infertility is one of the most common identifiable causes of human reproductive failure. Although considerable progress has been made toward understanding sperm physiology and the biology of gamete interaction, still more work is needed to achieve objectivity and standardization of some of the andrological diagnostic methods used in the clinical setting. More information is needed to definitively establish which tests are more accurate predictors of sperm performance and how they correlate with pregnancy potential following in-vivo and in-vitro interventions. Infertile men can be successfully treated with defined urological and medical therapies or with assisted reproductive technologies. Among the latter, intracytoplasmic sperm injection (ICSI) has become a validated means to overcome multiple sperm deficiencies. However, male infertility remains idiopathic in a large proportion of cases. As a consequence, it is expected that simplified and more cost-efficient therapeutic modalities will be developed as additional basic (cellular-molecular) and pathophysiological/clinical knowledge is gained.

Zona pellucida induced acrosome reaction, sperm morphology, and sperm-zona binding assessments among subfertile men

PURPOSE

The study aimed to evaluate the relationship between the zona pellucida induced acrosome reaction (ZIAR) and (i) percentage normal spermatozoa as well as (ii) sperm-zona pellucida binding potential among men referred for a routine semen analysis.

METHODS

Semen samples of 164 consecutive men referred to the andrology laboratory for routine semen analysis were studied. Semen samples were analyzed using the new WHO standards (strict criteria). ZIAR was recorded with a lectin conjugated Pisum sativum agglutinin microassay, while sperm-zona binding was evaluated with a standard hemizona assay (HZA).

RESULTS

Andrology patients were divided according to the percentage normal spermatozoa in the ejaculate, namely <4% normal forms (n = 71), 5-14%, normal forms (n = 73), and >14% normal forms (n = 20). ZIAR data of the <4%, 5-14%, and >14% groups was (9.6 +/- 0.6)%, (13.9 +/- 0.5)%, and (15.0 +/- 1.1)%, respectively. The ZIAR data of fertile control men was (26.6 +/- 1.4)% which differed significantly from the three andrology referrals groups. Likewise significant differences were recorded during the hemizona assay namely, 38.0% (<4% normal forms), 54.5% (5-1% normal forms), and 62.6% (>14% normal forms). Among the group with >14% normal forms, five cases had impaired ZIAR outcome (<15%). Three of these men had normal morphology and HZAs.

CONCLUSIONS

ZIAR testing should become part of the second level of male fertility investigations, i.e., sperm functional testing, since 15% of andrology referrals revealed an impaired acrosome reaction response to solubilized zona pellucida.

Identification and localization of T-type voltage-operated calcium channel subunits in human male germ cells. Expression of multiple isoforms

Low voltage activated, voltage-operated Ca(2+) channels are expressed in rodent male germ cells and are believed to be pivotal in induction of the acrosome reaction in mouse spermatozoa. However, in humans, very little is known about expression of voltage-operated Ca(2+) channels in male germ cells or their function. We have used reverse transcription-polymerase chain reaction, in situ hybridization, and patch clamp recording to investigate the expression of low voltage activated voltage-operated Ca(2+) channels in human male germ cells. We report that full-length transcripts for both alpha(1G) and alpha(1H) low voltage activated channel subunits are expressed in human testis. Multiple isoforms of alpha(1G) are present in the testis and at least two isoforms of alpha(1H), including a splice variant not previously described in the human. Transcripts for all the isoforms of both alpha(1G) and alpha(1H) were detected by reverse transcription-polymerase chain reaction on mRNA isolated from human spermatogenic cells. In situ hybridization for alpha(1G) and alpha(1H) localized transcripts both in germ cells and in other cell types in the testis. Within the seminiferous tubules, alpha(1H) was detected primarily in germ cells. Using the whole cell patch clamp technique, we detected T-type voltage-operated Ca(2+) channel currents in isolated human male germ cells, although the current amplitude and frequency of occurrence were low in comparison to the occurrence of T-currents in murine male germ cells. We conclude that low voltage activated voltage-operated Ca(2+) channels are expressed in cells of the human male germ line.