The hemizona assay: its role in identifying male factor infertility in assisted reproduction

Is it necessary to focus on morphologically normal acrosome of sperm during intracytoplasmic sperm injection?

Background & objectives:

The detailed assessment of sperm morphology is important in the semen of infertile men because there is a low proportion of normal spermatozoa. One of the parameters of such sperm morphology is the acrosome, and its effect on assisted reproductive outcomes is controversial. This study was undertaken to evaluate the association between different forms of acrosome on the chromatin status and the assisted reproductive outcomes.

Methods:

A total of 1587 unstained sperms from 514 infertile men were captured and analyzed for different acrosome forms (normal, large, small, skew, amorphous acrosome and without acrosome) in real time during intracytoplasmic sperm injection into oocytes. The association between the percentage of sperms with atypical acrosome and head shapes and the sperm chromatin status was studied. Fertilization, zygote and embryo quality and clinical pregnancy rates were calculated for different groups of sperms.

Results:

The highest frequency of irregular shapes of acrosomes, such as small, large and amorphous, was observed in abnormal ellipticity, anteroposterior symmetry and angularity parameters, respectively (P<0.05). The fertilization rate of injected sperms with large (P<0.01) and small (P=0.001) acrosomes and without acrosome (P=0.001) was significantly lower in comparison with normal acrosomes. The quality of zygotes (Z3, P=0.05), embryos (grade C, P<0.05) and the pregnancy rate (P=0.001) from injected sperms with large acrosomes were significantly lower compared with normal acrosomes.

Interpretation & conclusions:

Our findings showed that the different sperm acrosome morphologies (e.g., large, small, and without acrosome) might negatively relate with chromatin integrity and decrease the sperm's fertility potential and pregnancy rate during intracytoplasmic sperm injection (ICSI) cycles.

Selecting patients for embolization of varicoceles based on ultrasonography

Aim: The aim of the study was to assess patient selection for embolization of varicoceles based on ultrasonography. An additional objective of the work was to evaluate the results of endovascular treatment. Material and methods: From January 2015 till August 2017, 53 patients with varicoceles diagnosed in an ultrasound examination underwent endovascular treatment in the Department of Interventional Radiology and Neuroradiology in Lublin, Poland. Each ultrasound examination was performed using the Logiq 7 GE Medical System with a linear probe at 6–12 MHz using the B-mode and Doppler functions. The study was performed in both the supine and standing position of the patient. The morphological structures of the scrotum and the width of the pampiniform venous plexus were assessed. Based on clinical signs and symptoms as well as ultrasound findings, the patients were selected for endovascular treatment. This procedure involved the implantation of coils in the distal and proximal parts of the testicular vein and administration of a sclerosing agent between the coils. Results: Varicoceles were confirmed in all patients during a color Doppler scan. Diagnostic venography confirmed venous stasis or retrograde flow in the testicular vein and widened vessels of the pampiniform venous plexus over 2 mm in diameter in all patients undergoing endovascular treatment. The diagnostic efficacy of ultrasound was 100%. The technical success of the procedure was 89%. One patient had a recurrence of varicose veins (2.2%). There were no complications in any of the patients. Conclusions: Ultrasound is the preferred method in the diagnosis of varicoceles and selection for their treatment. Testicular vein embolization is a minimally invasive procedure characterized by high efficacy and safety.

Can Ultrasound Findings be a Good Predictor of Sperm Parameters in Patients With Varicocele? A Cross-Sectional Study

BACKGROUND

Varicocele, one of the most common causes of sperm abnormalities in men, is the dilation of the testicular vein (the pampiniform venous plexus) by more than 2 mm. Ultrasonography is the primary imaging procedure for varicocele diagnosis. The venous diameter is evaluated using B-mode sonography, and venous reflux is assessed using color Doppler sonography.

OBJECTIVES

In this study, we investigated the association of ultrasound findings with sperm parameters in patients with varicocele.

METHODS

Ninety-nine patients with clinically diagnosed varicocele were included in this study, which was performed at a university imaging center. Patients were evaluated for pampiniform venous plexus diameter, venous reflux, and testicular size on both sides. Semen analysis was performed for all patients. The ultrasonography parameters and semen analysis data were compared to assess the correlations between the results.

RESULTS

The semen analysis parameters, including semen volume and sperm morphology, count, and motility, significant correlations with the diameter of the varicocele vein but were not correlated with testes size. In addition, the patients with reflux of longer than 1 s and those with reflux of less than 1 s had significant differences in sperm parameters and varicocele size.

CONCLUSIONS

Our study showed that ultrasonography findings can be a good predictor of sperm parameters in patients with varicocele.

Assessing the reproductive health of men with occupational exposures

The earliest report linking environmental (occupational) exposure to adverse human male reproductive effects dates back to1775 when an English physician, Percival Pott, reported a high incidence of scrotal cancer in chimney sweeps. This observation led to safety regulations in the form of bathing requirements for these workers. The fact that male-mediated reproductive harm in humans may be a result of toxicant exposures did not become firmly established until relatively recently, when Lancranjan studied lead-exposed workers in Romania in 1975, and later in 1977, when Whorton examined the effects of dibromochloropropane (DBCP) on male workers in California. Since these discoveries, several additional human reproductive toxicants have been identified through the convergence of laboratory and observational findings. Many research gaps remain, as the pool of potential human exposures with undetermined effects on male reproduction is vast. This review provides an overview of methods used to study the effects of exposures on male reproduction and their reproductive health, with a primary emphasis on the implementation and interpretation of human studies. Emphasis will be on occupational exposures, although much of the information is also useful in assessing environmental studies, occupational exposures are usually much higher and better defined.

Hemizona assay and sperm penetration assay in the prediction of IVF outcome: a systematic review

The limited predictive value of semen analysis in achieving natural conception or in IVF outcome confirms the need for sperm function tests to determine optimal management. We reviewed HZA and SPA predictive power in IVF outcome, with statistical significance of diagnostic power of the assays. HZA was readily efficient in predicting IVF outcome, while evident inconsistency among the studies analysed framed the SPA's role in male fertility evaluation. Considerable variation was noted in the diagnostic accuracy values of SPA with wide sensitivity (52-100%), specificity (0-100%), and PPV (18-100%) and NPV (0-100%) together with fluctuation and notable differentiation in methodology and cutoff values employed by each group. HZA methodology was overall consistent with minor variation in cutoff values and oocyte source, while data analysis reported strong correlation between HZA results with IVF outcome, high sensitivity (75-100%), good specificity (57-100%), and high PPV (79-100%) and NPV (68-100%). HZA correlated well with IVF outcome and demonstrated better sensitivity/specificity and positive/negative predictive power. Males with normal or slightly abnormal semen profiles could benefit by this intervention and could be evaluated prior to referral to assisted reproduction. HZA should be used in a sequential fashion with semen analysis and potentially other bioassays in an IVF setting.

The pattern of tyrosine phosphorylation in human sperm in response to binding to zona pellucida or hyaluronic acid

In mammalian species, acquisition of sperm fertilization competence is dependent on the phenomenon of sperm capacitation. One of the key elements of capacitation is protein tyrosine phosphorylation (TP) in various sperm membrane regions. In previous studies performed, the pattern of TP was examined in human sperm bound to zona pellucida of oocytes. In the present comparative study, TP patterns upon sperm binding to the zona pellucida or hyaluronic acid (HA) were investigated in spermatozoa arising from the same semen samples. Tyrosine phosphorylation, visualized by immunofluorescence, was localized within the acrosomal cap, equatorial head region, neck, and the principal piece. Tyrosine phosphorylation has increased in a time-related manner as capacitation progressed, and the phosphorylation pattern was identical within the principal piece and neck, regardless of the sperm bound to the zona pellucida or HA. Thus, the data demonstrated that the patterns of sperm activation-related TP were similar regardless of the spermatozoa bound to zona pellucida or HA. Further, sperm with incomplete development, as detected by excess cytoplasmic retention, failed to exhibit TP.

In vitro competitive binding index using fluorochrome-labelled spermatozoa for predicting bull fertility

This work evaluated if an in vitro test, with the combined power of the statistical evaluation of spermatozoa and zona pellucida (ZP) competitive binding ability and a rapid method for accessory sperm counts, could predict the bull fertility. Ten Holstein Friesian bulls of known field fertility (five of high and five of low fertility) were selected. An in vitro heterospermic insemination approach, based on differential staining, was tested on 45 possible pairs of bulls (two batches per bull). Motility and quality (abnormalities and membrane status) seminal characteristics and estimated relative conception rates (ERCR) highlighted only one association between membrane integrity and ERCR (p = 0.007). Differences in ZP binding allowed us to rank bulls into two categories based on low and high binding ability. For eight bulls, this classification reflected the ERCR. Differences between batches were reported for two bulls, in which the effect of heterospermic insemination (the number of sperm binding to ZP from different bulls not in a 1:1 ratio) showed a significant bull-related effect (p < 0.001) in the first batch and no effect (p > 0.05) in the second batch for both bulls. Reduction of the number of oocytes per assay from 25 to 5 had no effect (p > 0.5) on the bulls’ ranking. Our results suggest that in vitro competitive binding is a promising approach for estimating bull fertility and support concepts for further implementation, e.g. drastic reduction of oocyte number in a single pair assay and larger scale testing for batches.

Bovine embryo development after IVF with spermatozoa having abnormal morphology

The study was conducted to evaluate the effects of scrotal insulation on semen samples collected from bulls on embryonic development after IVF. Semen samples were obtained and cryopreserved from four Holstein bulls before and after a scrotal insulation period of 48 h (Day 0). Three types of samples were used for IVF: (1) semen from the test bulls collected 5 d prior to scrotal insulation (pre-insult); (2) semen from Day 13 (2-week post-insult; 2-week PI); and (3) semen from Day 20 (3-week PI). After 18 h of sperm-oocyte co-incubation, the zygotes were cultured for 8 d when a developmental score (0=degenerate, 1=2-cell embryo through 5=blastocyst) was assigned to each embryo. The post-thaw morphological evaluation of sperm samples revealed a decrease (P<0.01) in the percentages of normal spermatozoa in the 3-week PI samples in comparison with the pre-insult samples for Bulls I and III (74-22.3% and 67.7-0.5 %, respectively). The percentage of vacuolated spermatozoa increased significantly for Bull II. The cleavage and blastocyst formation rates and embryo development scores were affected (P<0.01) by the interaction of bull by sample collection time. For Bulls I and III (severe responders) the scrotal insulation effects persisted from the time of cleavage through blastocyst formation. In contrast, the cleavage and blastocyst formation rates for Bulls II and IV were unaffected, despite high percentages of vacuolated spermatozoa present in the post-insult samples for Bull II. In conclusion, the use of scrotal insulation to elevate scrotal temperature was an effective method to obtain semen samples with high percentages of abnormal spermatozoa. The decrease in embryonic development after IVF when using spermatozoa with morphological abnormalities seemed to be multifaceted and related to changes in head morphology.

Sperm function and assisted reproduction technology

The evaluation of different functional sperm parameters has become a tool in andrological diagnosis. These assays determine the sperm's capability to fertilize an oocyte. It also appears that sperm functions and semen parameters are interrelated and interdependent. Therefore, the question arose whether a given laboratory test or a battery of tests can predict the outcome in in vitro fertilization (IVF). One-hundred and sixty-one patients who underwent an IVF treatment were selected from a database of 4178 patients who had been examined for male infertility 3 months before or after IVF. Sperm concentration, motility, acrosin activity, acrosome reaction, sperm morphology, maternal age, number of transferred embryos, embryo score, fertilization rate and pregnancy rate were determined. In addition, logistic regression models to describe fertilization rate and pregnancy were developed. All the parameters in the models were dichotomized and intra- and interindividual variability of the parameters were assessed. Although the sperm parameters showed good correlations with IVF when correlated separately, the only essential parameter in the multivariate model was morphology. The enormous intra- and interindividual variability of the values was striking. In conclusion, our data indicate that the andrological status at the end of the respective treatment does not necessarily represent the status at the time of IVF. Despite a relatively low correlation coefficient in the logistic regression model, it appears that among the parameters tested, the most reliable parameter to predict fertilization is normal sperm morphology. (Reprod Med Biol 2005; 4: 7-30).

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.

Zona-binding inhibitory factor-1 from human follicular fluid is an isoform of glycodelin

Zona-binding inhibitory factor-1 (ZIF-1), a glycoprotein in human follicular fluid, reduces the binding of spermatozoa to the zona pellucida. ZIF-1 has a number of properties similar to those of glycodelin-A from human follicular fluid. The objective of this study was to compare the biochemical characteristics of these two glycoproteins. N-terminal sequencing and protease-digested peptide mapping showed that ZIF-1 and glycodelin-A have the same protein core. However, these glycoproteins differ in their oligosaccharide chains, as demonstrated by fluorophore-assisted carbohydrate electrophoresis, lectin-binding ability, and isoelectric focusing. ZIF-1 inhibited spermatozoa-zona pellucida binding slightly more than did glycodelin-A and significantly suppressed progesterone-induced acrosome reaction of human spermatozoa. Indirect immunofluorescence staining revealed specific binding of glycodelin-A and ZIF-1 to the acrosome region of human spermatozoa, where ZIF-1 produced a stronger signal than did glycodelin-A at the same protein concentration. These data suggest that ZIF-1 is a differentially glycosylated isoform of glycodelin that potently inhibits human sperm-egg interaction. Future study on the function role of ZIF-1 would provide a better understanding of the regulation of fertilization in humans.

Localization of tyrosine phosphorylated proteins in human sperm and relation to capacitation and zona pellucida binding

Mammalian sperm must undergo a process known as capacitation before fertilization can take place. A key intracellular event that occurs during capacitation is protein tyrosine phosphorylation. The objective of this study was to investigate and visualize protein tyrosine phosphorylation patterns in human sperm during capacitation and interaction with the zona pellucida. The presence of specific patterns was also assessed in relation to the fertilizing capacity of the spermatozoa after in vitro fertilization. Protein tyrosine phosphorylation was investigated by immunofluorescence. Phosphorylation increased significantly with capacitation and was localized mainly to the principal piece of human sperm. Following binding to the zona pellucida, the percentage of sperm with phosphotyrosine residues localized to both the neck and the principal piece was significantly higher in bound sperm than in capacitated sperm in suspension. When the percentage of principal piece-positive sperm present after capacitation was <7%, fertilization rates after in vitro fertilization were reduced. Different compartments of human spermatozoa undergo a specific sequence of phosphorylation during both capacitation and upon binding to the zona pellucida. Tyrosine phosphorylation in the principal and neck piece may be considered a prerequisite for fertilization in humans.

Development of a new, highly sensitive zona pellucida binding assay using a bioluminescence-enhanced detection system

To date, two different zona binding assays have been described in the literature. Both assays, however, require a large quantity of human zonae which vary immensely in quality. Furthermore, an inverted microscope with micromanipulation equipment is necessary, which makes both assays relatively complicated and time-consuming, and requires skilled staff. Therefore, we developed a new, highly sensitive zona binding assay using a bioluminescence-enhanced system which employs a pool of solubilized zona pellucida and is easier for routine use. In the detection system, light emission by the luciferin-luciferase system is measured. Because of the limited availability of human zonae pellucidae, this new assay was first developed in the porcine system. The new bioluminogenic substrate D-luciferin-O-beta-galactopyranoside (Lu-Gal) was synthesized, purified and characterized. Synthesis of Lu-Gal resulted in purity better than 99.998%. Analytical data and spectra were appropriate. In terms of the kinetic data, Lu-Gal is a highly sensitive and specific substrate for beta-galactosidase. Using the given chemical conditions, nonlabelled zonae bound competitively to boar spermatozoa, which resulted in a high sensitivity and specificity. By the addition of 10 nonlabelled zonae, the binding of labelled zonae was almost completely inhibited. Corresponding results were obtained when the bioluminescent system was compared with the hemizona assay. On the other hand, spermatozoa of other species (bull, hamster and man) showed only low binding to the porcine zonae or none at all. Competitive displacement was not observed, indicating the inter-species specificity of the assay.

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

The study aimed to establish zona pellucida induced acrosome reaction response (ZIAR) among 35 couples with normal and G-pattern sperm morphology and repeated poor fertilization results during assisted reproduction treatment. ZIAR tests were performed using 0.25 zona pellucida/microliter co-incubated with spermatozoa for 60 min. Acrosome reactions were measured with FITC-PSA staining, and expressed as the difference between stimulated and unstimulated (spontaneous) sperm populations. Results were compared with IVF rates of metaphase II oocytes. Interactive dot diagrams divided the patients into two groups, i.e. ZIAR <15% and ZIAR > 15%, with mean fertilization rates of 49 and 79% respectively. The sensitivity and specificity for ZIAR results versus fertilization were 93 and 100% respectively. The area under the curve was 99% and the 95% confidence interval did not include 0.5 which implies that the ZIAR test is able to predict fertilization failure among IVF patients. In conclusion, the ZIAR test has diagnostic potential since it can assist the clinician to identify couples that will benefit from intracytoplasmic sperm injection therapy.

Can we use in vitro fertilization tests to predict semen fertility?

This presentation deals with assays based on in vitro fertilization (IVF) and related techniques such as zona pellucida (ZP) binding assays and oocyte penetration tests. These types of assays have been developed for several species of domestic animals. A description of the assays and how they have been performed in domestic animals, as well as data on the correlation between the results of assays and actual in vivo fertility are presented. Used either as single tests or in combination with other tests, this type of assay can provide valuable information about a semen donor, an insemination dose or a method of semen preservation.

Impact of fertilization history and semen parameters on ICSI outcome

PURPOSE

The objectives of this study were (1) to investigate intracytoplasmic sperm injection (ICSI) outcome according to its indications, i.e., a history of failed or poor fertilization and unsuitable sperm parameters for conventional IVF, and (2) to examine the impact of a female's age, sperm concentration, motility, morphology, presence of antisperm antibodies, and hemizona assay (HZA) results on overall outcome.

METHODS

Two hundred seventy-nine ICSI cycles performed in 207 couples were retrospectively evaluated.

RESULTS

Clinical pregnancy and delivery rates were 36.8 and 29.8% for patients with prior failed fertilization, 23.2 and 17.8% for patients who had prior poor fertilization, and 28.6 and 21.3% for patients with unsuitable sperm parameters. The differences among all groups were found to be insignificant. There was a significant, negative correlation between a female's age and pregnancy results. No difference was found in the three basic sperm parameters between those patients who produced and those who did not produce a pregnancy, but the fertilization rate was significantly higher in patients with more adequate sperm parameters. Although there was a trend toward a better fertilization rate in patients with a hemizona index (HZI) greater than 30 (indicative of a superior sperm-zona pellucida binding capacity) than in those with a HZI less than 30, the difference was not significant. There were no differences in fertilization rate according to the presence or absence of antisperm antibodies.

CONCLUSIONS

Fertilization history in a conventional IVF cycle has no effect on success rates following ICSI, and there is no correlation among the basic sperm parameters, the presence of antisperm antibodies, and pregnancy rates.

Relationship between sperm-zona pellucida binding assays and the 56-day nonreturn rate of cattle inseminated with frozen-thawed bull semen

Assays based on sperm-zona pellucida binding have been developed as diagnostic tests to predict the fertilizing potential of mammalian spermatozoa. Recently, we reported on the development of a sperm-zona pellucida binding assay (SZBA) for bull spermatozoa. The aim of the present study was to develop a hemi-zona assay (HZA) for bull spermatozoa and to investigate the relationship between SZBA and HZA outcomes and in vivo fertility. Frozenthawed semen samples from 8 fertile Swedish Red and White bulls (one ejaculate per bull) designated as the test semen samples and a single ejaculate from a fertile Holstein-Friesian bull designated as the control semen sample were used in this study. In the SZBA, 2 groups of 20 oocytes per semen test sample and in the HZA a minimum of 6 matching pairs of hemizonae were used for comparison of sperm binding with control semen. Sperm binding to matching hemi-zonae of individual semen samples was equal, and clearly demonstrated the feasibility of the HZA for cattle. A significant correlation was found between the SZBA and the HZA indices obtained from the different semen test samples (r = 0.42, P < 0.001; n = 67). There was no significant relation between the SZBA indices and the 56-d nonreturn rate of the test samples. However, the HZA indices of the semen test samples and the 56-d nonreturn rate were significantly correlated (r = 0.46, P < 0.0001; n = 67). It is concluded that HZA can be regarded as a potential assay for predicting the fertilizing ability of bovine semen samples. However, further studies using more semen samples are necessary to confirm this view.

Aging, hyaluronidase removal of the cumulus, and microinjection do not affect the sperm binding potential of human oocytes

PURPOSE

We studied the influence of aging, hyaluronidase removal of the cumulus, and microinjection on the sperm binding potential of human oocytes under intact zona assay conditions to determine the safe use of unstored aged unfertilized ICSI oocytes on zona binding tests. Results were also compared with those for aged IVF oocytes under the same conditions.

METHODS

To avoid the large variation in sperm binding scores, we compared the ratios of the number of sperm bound to nontreated versus to treated oocytes. Treated oocytes were those whose zonae were exposed to hyaluronidase, an agent that decreases sperm binding. Experimental groups were fresh oocytes, experimentally aged fresh oocytes, fresh oocytes whose cumulus was removed either mechanically or with hyaluronidase, aged ICSI oocytes, and aged IVF oocytes.

RESULTS

Statistical analysis within and between groups showed that aging, previous insemination, cumulus removal by hyaluronidase, and microinjection did not affect the sperm binding potential of human oocytes.

CONCLUSIONS

As the zona binding ability of fresh and unfertilized aged ICSI oocytes is similar, they can be used safely in zona assays.

Prognostic value of the strict criteria: an Argentinian experience

The prognostic value of normal sperm morphology, evaluated according to the strict criteria, was prospectively assessed. The study included 112 IVF cycles. The percentage normal sperm morphology of the semen samples used in each cycle was determined and assigned to one of three prognostic groups; P-pattern (< 4% normal forms), G-pattern (5-8% normal forms), and N-pattern (> 8% normal forms). The fertilization, grade 4 embryo attainment, and pregnancy rates were compared between the three groups. The fertilization rate of the N-pattern group (83.7%) was significantly higher than that of the G-pattern (59.65%) and the P-pattern (22.58%) groups. The grade 4 embryo attainment rate was only significantly different between the N-pattern (23.38%) and the P-pattern (4.76%) groups. No pregnancy was obtained in the P-pattern group compared to a pregnancy rate per transfer of 23.08% in the N-pattern group. This study reaffirms the interlaboratory reproducibility and the prognostic value of normal sperm morphology.

Review: in vitro spermicidal tests

This review analyzes in vitro spermicidal tests that have been used to evaluate the spermicidal activity of contraceptive products. Special requirements and processes in numerous technologies were also reviewed. Nonoxynol-9 (N-9) was used as an example of a vaginally delivered spermicidal agent, and its spermicidal potency was compared by various spermicidal tests, such as Sander-Cramer, computer-assisted semen analysis, hypoosmotic swelling test, cervical mucus penetration test, and flow cytometry, and advantages and disadvantages of each test were specified. This provides an insight into the different aspects of sperm functionality on which each spermicidal agent exerts its activity. A rationale of the best combination of in vitro spermicidal tests, with particular emphasis on a simple and efficient strategy that targets the complete fertility control, was explained.

In vitro fertilization failure: identification of gamete defects by investigation of sperm-zona pellucida binding capacity of unfertilized oocytes

The objective of the study was to determine whether fertilization failure was due to spermatozoal or oocyte factors. Twenty-five unfertilized oocytes from 12 IVF/GIFT couples showing total or partial fertilization failure were evaluated for sperm zona binding potential under hemizonaeassay (HZA) conditions. Hemizonae were separately incubated with a sperm sample from the husband and that of a fertile control. Tight sperm binding to hemizonae was assessed. First, among the 12 patients, results showed a possible zona defect thought to be the cause of fertilization failure in five cases. Second, in two cases, fertilization failure was possibly caused by poor sperm binding potential of spermatozoa. Third, in two cases, fertilization failure was possibly caused by an oocyte defect, and fourth, three cases showed a mixture of possible causes. The results stress the need to develop a sequential analytic programme for those couples with repeated total or partial fertilization failure.

Acrosomal morphology as a novel criterion for male fertility diagnosis: relation with acrosin activity, morphology (strict criteria), and fertilization in vitro

OBJECTIVE

To determine the relationships between sperm acrosin activity, sperm morphology evaluated according to strict criteria, visually observed acrosomal morphology, and IVF rates.

DESIGN

Prospective analytic study. Acrosin activity was determined on all semen samples together with a standard semen analysis. Emphasis was placed on sperm morphology and especially a novel criterion viz acrosome morphology (acrosome index) as recorded with bright field microscopy.

SETTING

University-based tertiary care center.

PATIENTS

Thirty-three couples undergoing IVF or GIFT with two or more metaphase II ova inseminated in vitro.

MAIN OUTCOME MEASURE

In vitro fertilization rates of inseminated ova.

RESULTS

Strong correlations were found between acrosome index, normal sperm morphology, and IVF rates. An acrosome index cutoff value could be established at > 10% normal acrosomes for IVF rates of > or = 50% (sensitivity and specificity = 100%) and an acrosin activity cutoff value at > 18 microIU/10(6) sperm. A multiple linear regression analysis showed that the acrosome index and acrosin activity added a significant contribution to the explanation of the variation in the fertilization rates.

CONCLUSIONS

A strong positive correlation was found between acrosome index and IVF rates. Although the numbers of the study are small, the results indicate that the acrosome index possibly may be regarded as an additional tool in the prediction of IVF outcome and especially may be of value in the group of men with severe teratozoospermia, i.e., < or = 4% morphologically normal spermatozoa.

Sperm binding to the human zona pellucida after migration through human cervical mucus

During lactational amenorrhea a special type of cervical mucus, similar to that found during the luteal phase, is produced. This mucus, however, is able to support sperm migration. In the study described, the ability of spermatozoa to bind to the human zona pellucida (hZP) after migration through periovulatory and post-partum mucus was studied. Mucus was obtained from exclusively breastfeeding women in amenorrhea at 30, 60, 120 and 180 days post-partum. Periovulatory mucus samples from normally cycling women were used as a control. Flat capillary tubes were filled with BWW culture medium at the top and cervical mucus at the bottom. The tubes were immersed in a semen reservoir and the spermatozoa allowed to migrate through the mucus for 3 h into the culture media. Then the spermatozoa were coincubated with 3-4 hZP for 30 min and the number of bound spermatozoa per zona was counted. Periovulatory cervical mucus had an average Insler score of 14 +/- 0.5 as compared to 4.6 +/- 0.4 for post-partum mucus. Spermatozoa recovered from periovulatory mucus were always able to bind to the hZP in only 68 +/- 7% of the cases. Moreover, spermatozoa recovered from post-partum mucus bound to the ZP in lower numbers than did spermatozoa recovered fro periovulatory mucus (p < 0.03). These results suggest a greater ability of sperm-hZP binding after migration through periovulatory mucus and they also indicate that sperm binding to the ZP is possible even after sperm migration through a low quality mucus.

Fluorescein isothiocyanate conjugate-wheat germ agglutinin staining of human spermatozoa and fertilization in vitro

OBJECTIVE

To determine the sensitivity and clinical significance of fluorescein isothiocyanate wheat germ agglutinin (FITC-WGA) staining of human spermatozoa.

DESIGN

Percentage FITC-WGA staining was assessed in the different morphological zones of human spermatozoa and compared with fertilization rates of metaphase II oocytes in vitro.

PATIENTS

Spermatozoa and oocytes were obtained from normospermic (n = 12) and male factor patients (n = 15) attending the Tygerberg Hospital's IVF clinic.

MAIN OUTCOME MEASURES

Aliquots of swim-up spermatozoa used in the IVF laboratory were examined for the presence and morphological localization of WGA receptors. Fertilization rates were expressed as the percentage of metaphase II oocytes with successful fertilization.

RESULTS

Human spermatozoa capacitated in vitro for use in an IVF program showed variations in the percent positive staining of the acrosomal region which correlated with IVF rates in both patient groups studied. Values of FITC-WGA acrosomal staining of < 35% corresponded with IVF rates of < 50% whereas > 35% WGA acrosomal staining corresponded with IVF rates > or = 50%. Significant differences between acrosomal and equatorial region staining from normozoospermic samples and male factor samples also were observed.

CONCLUSION

The results indicate the practical use of the WGA assay for molecular assessment of male fertilizing capacity in conjunction with an assisted reproductive program.

The effect of egg yolk on the binding capacity of human spermatozoa to zona pellucida

OBJECTIVE

To evaluate the effects of Tes and Tris (TEST)-yolk buffer (TYB) incubation on sperm function.

DESIGN

Sperm samples obtained from 61 patients attending the infertility clinic were incubated in TYB and control medium. Binding to the zona pellucida (ZP), evaluated by the hemizona assay, membrane functional integrity evaluated by the hypoosmotic swelling test, and acrosome reaction and penetration through cervical mucus were assessed to ascertain the effect of TYB treatment.

RESULTS

The only substantial effect of TYB treatment was enhanced sperm binding to the ZP. The mean number of sperm cells attached to the hemizonae with TYB or medium treatment, was 42 +/- 6.1 (+/- SE) and 31 +/- 5.8, respectively (n = 61). However, this improvement was most obvious in 12 patients whose sperm samples exhibited a marked increase in sperm binding capacity following TYB treatment compared to medium without TYB, 71 +/- 5.6 and 12 +/- 2.7, respectively. In the other sperm samples (n = 49), sperm binding capacity was similar following TYB and medium treatment (both 35 +/- 6.0).

CONCLUSIONS

A 2-hour incubation of sperm samples with TYB-containing medium (at room temperature) enhances the binding capacity of human spermatozoa in approximately 20% of patients considered to have male factor infertility. The basis of this selective effect has yet to be studied further.

Sperm-zona pellucida binding of human sperm is correlated with the immunocytochemical presence of proacrosin and acrosin in the sperm heads but not with the proteolytic activity of acrosin

OBJECTIVE

To determine whether the sperm-zona pellucida (ZP) binding is related to the presence of immunoreactivity for proacrosin and acrosin and/or to the proteolytic activity of acrosin.

SETTING

The Andrology Clinic, University of L'Aquila, Italy.

PATIENTS

Thirty-five infertile couples and 15 men of proven fertility.

INTERVENTIONS

Salt-stored unfertilized oocytes after IVF were inseminated with a mixture of equal numbers of test and fertile donor sperm after swim-up selection, respectively labeled with fluorescein or rhodamine. Total acrosin activity, the percent of sperm immunostained for proacrosin and acrosin, and the percent of sperm with oval heads were evaluated in fresh semen and after swim-up selection.

MAIN OUTCOME MEASURES

Three zonae were used for each patient and sperm-ZP binding ratio (ZP ratio) was calculated as the total number of test sperm bound to ZP divided by the total number of control sperm bound to ZP. The ZP ratio was compared with the percent of live sperm immunostained for proacrosin and acrosin, with total acrosin activity and with the percent of sperm with oval heads after swim-up selection.

RESULTS

The sperm-ZP binding ratio was correlated positively with the percent of sperm immunostained for proacrosin and acrosin and with the percent of sperm with oval heads, but not with acrosin activity. Ejaculates with immunostaining for proacrosin and acrosin > or = 55% of sperm (the mean value of infertile couples) and acrosin activity < 24 muIU/10(6) sperm (the mean value of infertile couples) (n = 8) had a ZP ratio > or = 0.5, whereas ejaculates with low immunostaining for proacrosin and low acrosin activity (n = 12) had a ZP ratio < 0.5. The difference between the ZP ratio of the two groups was highly significant.

CONCLUSIONS

The ZP binding is related to the immunocytochemical presence of proacrosin and acrosin but not to the proteolytic activity of acrosin in human sperm, suggesting that egg recognition and proteolytic activity are independent functions of proacrosin and acrosin.

The hemizona assay is of good prognostic value for the ability of sperm to fertilize oocytes in vitro

OBJECTIVES

To assess the prognostic value of hemizona assay (HZA) in predicting the success of IVF.

DESIGN

Samples from 133 patients, who were referred for semen evaluation, were tested by HZA. Thirty samples were tested twice to assess interassay variation. Seventy couples were also referred for IVF. Results of HZA were compared with standard parameters of sperm quality, fertilization rates, and pregnancies.

RESULTS

The intra-assay and interassay coefficient of variation were 8% and 14%, respectively. Hemizona assay results had the highest correlation with sperm morphology (r = 0.60). Of all parameters evaluated, fertilization rates were best predicted by hemizona index (HZI) (r = 0.75). The assay was found to have high sensitivity and specificity rates, at a threshold HZI of 23%.

CONCLUSIONS

The HZA is a valuable prognostic test for IVF. With a threshold HZI of 23%, it has a good predictive value for fertilization rates in IVF, and may thus be used for patient preselection before IVF.

Development of a predictive model for optimal zona pellucida binding using insemination volume and sperm concentration

OBJECTIVE

To develop a predictive model under hemizona assay (HZA) conditions for human spermatozoa concentrations and insemination volume for optimum zona pellucida (ZP) binding.

DESIGN

Analysis of 20 different insemination volumes for zona binding and sperm morphology under HZA conditions.

SETTING

Reproductive biology unit, tertiary medical center.

PATIENTS

Four proven fertile sperm donors.

MAIN OUTCOME MEASURES

5-, 20-, 50-, 80-, and 100-microL droplets were analyzed with four different concentrations of 0.5 x 10(6), 1.0 x 10(6), 2.0 x 10(6), and 4.0 x 10(6) cells/mL to determine the number of sperm bound to each hemizona. Fifteen hemizonae were used for each insemination volume or microdroplet. Response surface regression model with volume and concentration as the regressor variables has been used.

RESULTS

The response surface of binding for the factors concentration and volume showed nonlinear association. A formula, indicating the optimal sperm insemination volume for maximum sperm binding to the ZP, Vmax = -(b1 + b5c)/2b6c, is described. The transformed data indicated 60 microL containing 4 x 10(6) sperm/mL to be optimal. Although morphology of zona spermatozoa is superior compared with seminal and postswim-up samples, no difference among the percentage of the normal morphology in different microdroplets could be demonstrated.

CONCLUSION

Optimal volume for the obtained concentration of spermatozoa from a patient can be calculated and therapeutically used for cases of severe oligozoospermic patients by microvolume inseminations in IVF practice.

Sperm-oocyte interaction: studies on the kinetics of zona pellucida binding and acrosome reaction of human spermatozoa

Successful sperm-oocyte interaction depends, among other things, on sperm capacitation, which is defined by acrosomal and motility alterations. In the study described here the authors evaluated different aspects of this gamete interaction in humans. Specifically, the authors studied (1) the relationship between the number of spermatozoa bound to the zona pellucida and sperm concentration and incubation period, (2) the capacitation status and kinetics of acrosome reaction among the zona-bound spermatozoa, and (3) the effect of human follicular fluid on the zona-binding potential and acrosome status of spermatozoa from different men. The results indicated a concentration of 10(7) cells ml-1 after 15 min of coincubation to be the optimum for zona binding. The number of sperm bound after 0, 3 and 5 h of incubation was the same. In addition, spermatozoa incubated for 3 or 5 h underwent the acrosome reaction (range 9-43%) on the zona surface within 15 min of binding. The maximum percentage of acrosome-reacted spermatozoa was reached after 60 min of binding. Follicular fluid affected the sperm populations selectively, since it did not influence zona binding capacity in all cases. The data enhances the authors' understanding of critical events occurring before fertilization.