Correlation of human in vitro fertilization with the hamster egg bioassay

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 progressive simplification of the infertility evaluation

OBJECTIVE

With the advent of evidence-based medicine, much of the complex testing that infertile couples used to undergo is no longer recommended as part of the routine evaluation. Examples of tests no longer implemented include the postcoital test, Rubin test of tubal patency, endometrial biopsy, sperm antibody testing, and the zona-free hamster test. The role of routine diagnostic laparoscopy and hysteroscopy is also reviewed.

CONCLUSIONS

In 2010, the simplicity of the current evaluation of couples presenting with infertility is essential information for patients to know at the initial visit. Ideally, it can help alleviate anxiety and provide patients with a road-map during a visit that is often associated with stress and high emotions.

TARGET AUDIENCE

Obstetricians & Gynecologists, Family Physicians.

LEARNING OBJECTIVES

After completion of this educational activity, the obstetrician/gynecologist should be better able to assess the current recommendations for evaluating infertile couples; examine the various ways to assess ovarian reserve, the uterine cavity, and fallopian patency; and appraise the controversy surrounding diagnostic surgery.

Diagnostic significance of sperm-zona pellucida interaction

Spermatozoa binding to the zona pellucida is an early, critical event leading to fertilization and early pre-embryo development. Fertilization involves a complex and orderly sequence of events that is completed at syngamy, which is defined as the union of the two sets of haploid chromosomes to form a new diploid fertilized ovum (zygote). In order to be able to fertilize an oocyte, spermatozoa need to undergo a process called ‘capacitation’, which is usually defined as a series of changes that renders the sperm cells capable of undergoing the acrosome reaction. This process that naturally occurs within the female genital tract is possible under in vitro conditions. However, capacitation is not the only process spermatozoa must undergo to fertilize the oocytes successfully. To fertilize an oocyte, spermatozoa must also be at least highly motile, as well as being capable of undergoing the acrosome reaction timely, penetrating through the oocyte investments and fusing with the oocyte plasma membrane properly.

The association between polypronucleate zygote formation with certain motion characteristics of sperm and IVF outcome

PURPOSE

To determine the efficiency of sperm motion characteristics as predictors for normal (2PN) and polypronulceate (PPN) zygotes in IVF.

METHODS

A retrospective cohort analysis for a total of 230 couples undergoing IVF treatment in a single infertility center.

RESULT(S)

Subsequent to semen analysis and hemizona assay, unexpected fertilization failure would appear to have occurred only extremely rarely (1/236, 0.4%). The rate of PPN, however, did arise and appeared to be related to certain sperm motion characteristics, such as lateral head displacement and concentration of progressive motile sperm. Interestingly, the patients featuring a high PPN rate (>20%) was associated with a greater pregnancy rate than those featuring a low PPN rate (<20%).

CONCLUSION

The sperm motion characteristics examined herein could be utilized to predict the rate of PPN in IVF. In order to enhance the rate of 2PN and maintain the relative high rate of clinical pregnancy, an efficient method needs further investigation and development.

Sperm protamine 1/protamine 2 ratios are related to in vitro fertilization pregnancy rates and predictive of fertilization ability

OBJECTIVE

To evaluate whether aberrant sperm P1/P2 ratios are predictive of abnormal fertilizing ability and are related to in vitro fertilization (IVF) outcome.

DESIGN

Prospective case-control study.

SETTING

University-based infertility and IVF clinic.

PATIENT(S)

Forty-three male infertility patients with an abnormally reduced P1/P2 ratio, 251 patients with a normal P1/P2 ratio, and 121 patients with an abnormally elevated P1/P2 ratio.

INTERVENTION(S)

Human IVF, the sperm penetration assay (SPA), and sperm protamine quantification via nuclear protein extraction, gel electrophoresis, and densitometry analysis.

MAIN OUTCOME MEASURE(S)

Sperm P1/P2 ratios; P1 and P2 quantities; SPA scores; and IVF-fertilization, embryo-quality, pregnancy, delivery, and spontaneous-abortion rates.

RESULT(S)

Standard IVF fertilization rates and SPA scores were significantly reduced in patients with abnormally low and high P1/P2 ratios. In vitro fertilization embryo quality was comparable between these groups, but pregnancy rates were significantly reduced in patients with abnormally reduced P1/P2 ratios.

CONCLUSION(S)

The P1/P2 ratio has a significant relationship to sperm fertilization ability. The relationship between protamines and fertilization ability is not understood but may be either a reflection of generalized abnormalities during spermiogenesis or an indication of protamine deficiency acting as a regulator or checkpoint of spermatogenesis.

Simple histochemical stain for acrosomes on sperm from several species

The acrosome reaction is an exocytotic process that enables a sperm to penetrate the zona pellucida and fertilize an egg. The process involves the fenestration and vesiculation of the sperm plasma membrane and outer acrosomal membrane releasing the acro somal contents. Many different methods have been devel oped to detect the acrosomal status of sperm. These techniques are sometimes complicated, costly, and can be used on only a few species. The aim of this study was to develop an efficient and inexpensive method to assess the acrosomal status of sperm from a variety of species. We prepared and fixed sperm from humans, cattle, swine, rabbits, guinea pigs, and mice and stained them with Coomassie G250. The acrosomes were stained intensely blue in color. Following capacitation, some sperm were incubated for 1 hr with 10 microM calcium ionophore A23187 to induce the acrosome reaction. They were also stained with Coomassie G-250. Ionophore-treated sperm lacked Coomassie staining over the acrosomal region. Differential interference contrast (DIC), bright field microscopy or Pisum sativum agglutinin staining confirmed that the acrosomes of sperm from these species were reacted in response to calcium ionophore treatment and the acrosome reaction frequencies matched results with Coomassie staining. These results demonstrate that the acrosomal status of mammalian sperm from several species can be determined easily and reliably using this simple Coomassie Blue G-250 staining method.

The correlation of sperm chromatin decondensation following in vitro exposure to heparin and sperm penetration rates

PURPOSE

The aim of this study was to evaluate the possible correlation of low-dose heparin-induced decondensation of sperm chromatin with sperm concentration, motility, morphology, membrane hypoosmotic response, ejaculate volume, and the ability of sperm to penetrate zona-free hamster oocytes.

METHODS

Twenty-two donors of known fertility and 105 patients undergoing evaluation at an andrology laboratory were evaluated by standard World Health Organization semen analysis techniques and a modified sperm penetration assay (SPA). An aliquot was also incubated for 60 min and Ham's F10 medium containing 50 USP/ml heparin. The percentage of sperm undergoing chromatin decondensation was evaluated and correlated to SPA rates and semen quality parameters.

RESULTS

No significant correlation was observed between semen parameters and decondensation rates. A nonsignificant (P = 0.11) inverse correlation (P = -0.21) was observed between SPA rates and chromatin decondensation. Significant (P < 0.001) differences were observed in the decondensation rate of donors (3.7 +/- 0.6), patients with normal SPA rates (7.8 +/- 1.5), and patients with decreased SPA rates (21.7 +/- 1.8). The decondensation rates were significantly different (P < 0.01) between patients with a normal SPA rate and patients with a decreased SPA rate.

CONCLUSIONS

These data indicate a significant inverse relationship between the SPA rate, which has previously been shown to correlate highly with fertilization ability and heparin-induced sperm chromatin decondensation.

Semen analysis and antisperm antibody

Evaluation of the fertilizing potential of sperm is an important procedure in in vitro fertilization and embryo transfer (IVF-ET) clinic, in order to avoid performing invalid conventional IVF-ET or unnecessary intracytoplasmic sperm injection (ICSI). However, none of the standard semen parameters are reliable indices in predicting IVF outcome. The test examining sperm-zona interaction is the best present method, though the short supply of the human zona component should be solved. IVF-ET treatment is useful for pregnancy in women having sperm immobilizing antibodies because it avoids exposing sperms to antibodies that block fertilization. ICSI should be used in immunologically infertile men diagnosed by specific method to demonstrate the in vivo exposure of sperms to antisperm autoantibodies that block fertilization.

Relationship of acrosin activity to sperm function tests

Acrosin activity of spermatozoa from infertile patients and fertile volunteers was measured. Acrosin activity of spermatozoa from asthenozoospermic patients and patients with unexplained infertility was lower than that from fertile volunteers. We utilize the zona-free hamster egg-sperm penetration test to select candidates for conventional in vitro fertilization among unexplained infertile patients. The zona-free hamster egg sperm penetration test, however, requires several hours and special equipment which are not used in the clinical setting. It is preferable that other sperm function tests or a combination of them can replace this test. Thus three distinct tests of sperm function, namely, acrosin activity, Penetrak test, hypo-osmotic swelling test, were compared with the hamster test, using spermatozoa from patients with unexplained infertility. A combination of the Penetrak test and measurement of acrosin activity could predict the results of the zona-free hamster egg sperm penetration test with 88.2% accuracy. Thus, the hamster test should be done when either Penetrak test or measurement of acrosin activity showed abnormal values.

Fertilizing ability of sperm with unexplained in vitro fertilization failures, as assessed by the zona-free hamster egg penetration assay: its prognostic value for sperm-oolemma interaction

OBJECTIVE

To investigate the fertilizing ability of sperm with previous unexplained IVF failure using the zona-free hamster egg penetration assay.

DESIGN

Three hundred ninety-six tests were performed after multiple IVF failures. In a subsequent prospective study, 38 IVF attempts using the microdrop insemination technique and 81 subzonal inseminations (SUZI) were performed. One hundred thirty-two tests with donor sperm were carried out as controls.

PATIENTS

Three hundred fifty-two patients who had a minimum of two unexplained IVF failures including at least 10 metaphase II oocytes were included in the study.

RESULTS

The ability of the patient sperm to bind to hamster oocytes was lower than that of controls. The largest differences were the percentage of oocytes with swollen sperm heads and the mean number of decondensed sperm heads per penetrated oocyte: both were much lower for patients than controls. Patients with a test result nil did not fertilize any oocytes during the SUZI cycles (n = 7; 50 oocytes), and the post-SUZI fertilization rate for patients with a test value < 10% was significantly lower than that of others (5.4 +/- 10.3 versus 23.8 +/- 8.4, respectively).

CONCLUSIONS

The defect of sperm involved in IVF failures is mainly a reduction of their fusiogenic ability and not their ability to recognize and bind to the oolemma. Patients with a test result < 10% had a significantly reduced post-SUZI fertilization rate. A test score of zero indicates a major and permanent impairment of the sperm fusiogenic ability.

A quality control system for the optimized sperm penetration assay

OBJECTIVE

To develop a quality control system for the optimized sperm penetration assay (SPA) and to use this system to monitor interassay variability and stability over time.

DESIGN

Four semen donors were tested consecutively for a period of weeks (7 to 139 weeks) with the SPA. Their average semen analyses and SPA scores were evaluated to monitor natural biologic variation. Intra-assay variation was obtained by dividing 11 semen samples into three aliquots and testing each separately in the SPA. A single ejaculate from seven individuals was aliquoted and frozen to be used as a control. They were tested on different assay days in 1986 and subsequently in 1991 to evaluate the assay stability over time.

MAIN OUTCOME MEASURES

Results were expressed as a sperm capacitation index (mean number of sperm penetrations per ovum).

RESULTS

Consecutive weekly semen analyses and SPAs on donors exhibited coefficients of variation ranging from 20% to > 40%. In contrast, these variations were much greater than intra-assay variability. Analysis of frozen semen specimens tested in several SPAs also displayed a low coefficient of variation. When aliquots of these frozen samples were tested in the SPA 5 years later, there were no differences in the observed values, showing the remarkable stability of this assay over time. The lower limit of the normal fertile range did not change over a period of 2 years.

CONCLUSIONS

Results show that using fresh semen samples as a positive control in the SPA is inadequate. This deficiency has been overcome with the use of frozen semen controls. With frozen semen for quality control, the optimized SPA developed in this laboratory is a highly reproducible assay that meets the strict criteria required for clinical laboratory certification.

The importance of the hypoosmotic swelling test and acrosin activity assay for identifying subpopulations of idiopathic infertile men

Semen samples collected from fertile donors (n = 13) and pooled samples from idiopathic infertile men (n = 19) were used in this study. Measurements of the total sperm acrosin activity and the hypoosmotic swelling test (HOST) were performed in all the samples. The percentage of swollen spermatozoa and acrosin profiles were significantly lower in the infertile men than in the fertile donors. Considering the lowest values of the outcome of the HOST and the acrosin activity assay in the group of fertile men as the lowest normal values, it was proven that HOST and acrosin activity assay could identify subpopulations of infertile men of 37 and 26%, respectively. The results tend to support the employment of the HOST and the acrosin activity assay in the evaluation of idiopathic infertile men.

Prediction of in vitro fertilization outcome by sperm penetration assay with TEST-yolk buffer preincubation

OBJECTIVE

To evaluate sperm penetration assay (SPA) value as a screening tool before in vitro fertilization (IVF).

DESIGN

Follow-up study comparing sperm variables and IVF outcome.

SETTING

Infertile couples in an academic research environment.

PATIENTS, PARTICIPANTS

Two hundred forty-one infertile couples scheduled for IVF.

INTERVENTIONS

Sperm penetrating assay with cold Tes-TRIS (TEST) Yolk buffer semen preincubation and IVF.

MAIN OUTCOME MEASURES

Percent of egg penetration recoded into poor and good category (0% to 20%, 21% to 100%) and compared with fertilization, embryo transfer, and pregnancy rate (PR) in IVF, as well as sperm count motility and morphology.

RESULTS

Sperm penetrating assay predicted fertilization with a high negative (74%) and positive (82%) predictive rate and good specificity value (0.96). One of 31 patients in the poor SPA category (3%) fertilized less than 50% of eggs; no pregnancy occurred. In the good SPA category, 87 of 210 patients (41%) fertilized greater than or equal to 50% of eggs with 34.3% PR. Sperm penetrating assay correlated better with fertilization rate than did sperm count and motility but not morphology.

CONCLUSIONS

Sperm penetrating assay is a useful screening assay before IVF together with sperm morphology.

Tests of human sperm function and fertilization in vitro

OBJECTIVE

To review recent studies on the development of new tests of human sperm function and evaluation of which sperm characteristics are most important for fertilization in vitro by logistic regression analysis.

STUDY SELECTION

Recent studies on the relationship between putative and new tests of human sperm function and fertility in vitro or in vivo are discussed in this review. Some physiological and technical aspects are included.

MAIN OUTCOME MEASURES

Fertilization rates in vitro and sperm tests including standard semen analysis, improved morphology assessment, objective assessment of sperm motility and movement characteristics, nuclear maturity, hypo-osmotic swelling, the acrosome and the acrosome reaction, acrosin activity, human sperm-hamster oocyte penetration assay, and sperm-zona pellucida (ZP) and sperm-oolemma binding.

RESULTS

The percentages of sperm with normal morphology and a normal intact acrosome, mean linearity, and the number of sperm binding to the ZP were highly significant related to fertilization rates in vitro. Other sperm tests evaluated usually provided no additional information about fertilization rates. The human ZP is highly selective for binding of morphologically normal sperm. Acrosome-reacted human sperm have little or no ability to bind to the ZP.

CONCLUSION

Results of in vitro fertilization can be used to evaluate tests of human sperm function. Logistic regression analysis is a powerful method for determining which groups of sperm characteristics are independently related to fertilization rates. Normal morphology, linearity, acrosome status, and sperm-ZP binding are the most important characteristics for fertilization in vitro.

Evaluation of testicular function

The evaluation of testicular function is based primarily on a detailed medical history, a careful physical examination, basal measurements of FSH, LH and testosterone and a routine semen analysis. In a patient with androgen deficiency, the diagnosis can often be made with these basic tests. The clinician will then decide on other investigations to localize the organic lesion and to plan further treatment for the patient. Sperm function tests are often performed in patients presenting with infertility. These newer tests may help to delineate the abnormality of the spermatozoa at each stage during the achievement of fertilizing capacity such as adequate forward motility, penetration of cervical mucus, acrosome reaction, development of hyperactivated motility, binding to the zona pellucida, and fusion with the oocyte. Currently, many of these sperm function tests depend on cumbersome bioassays with many limiting factors contributing to their availability, accuracy and precision. The development of biochemical tests as markers of sperm function may allow more precise definition of sperm functional abnormalities. With the continued improvement of computer-aided sperm analysis, objective motion parameter measurements are possible and morphological assessment are being developed. These newer objective methods of semen analysis have to be shown to be valuable in the clinical assessment of patients with testicular dysfunction.

Comparative study on the use of human follicular fluid or egg yolk medium to enhance the performance of human sperm in the zona-free hamster oocyte penetration assay

A prospective study was conducted on 61 unselected semen samples from infertile patients to compare the efficacy of human follicular fluid (hFF) or TEST-egg yolk medium treatment in enhancing sperm performance in the zona-free hamster oocyte penetration (HOP) test. Both hFF and TEST-egg yolk enhanced penetration scores significantly in the HOP test in comparison with the control swim-up sperm preparation. The TEST-egg yolk medium treatment, however, exhibited the highest penetration scores, and there were higher percentages of preparations passing the 10 or 20% penetration rate cut-off point with sperm exposed to the TEST-egg yolk medium than those exposed to hFF. These results indicate that modification of the original HOP-test protocol by incorporation of TEST-egg yolk medium gives a greatly increased penetration rate when compared to the addition of hFF in such a system.

An evaluation of various treatments to increase sperm penetration capacity for potential use in an in vitro fertilization program

OBJECTIVE

To select in vitro fertilization (IVF) patients with a low sperm penetration assay (SPA) value and to determine if the penetration rate, fertilization rate, and the pregnancy rate (PR) can be improved in these patients by treating sperm with refrigeration, calcium ionophore A23187, prostaglandin E1, prostaglandin E2, or heparin.

DESIGN

The study consists of three parts: identification of patients with poor SPA values, analysis of treatments to improve the SPA value, and evaluation of the treatments to improve fertilization and PRs.

RESULTS

The data indicate that treatment of sperm with refrigeration can improve fertilization and PRs during IVF in selected patients previously shown to have an improved SPA value with the treatment.

CONCLUSIONS

Three points are emphasized: (1) the treatments analyzed in this study can improve SPA values in some of the patients with low sperm penetration capacity; (2) of the treatments studied, sperm refrigeration resulted in the largest improvement in sperm penetration capacity; and (3) sperm refrigeration can increase fertilization and PRs during IVF in this select group of patients.

Fertilization failure and dysfunctions as possible causes for human idiopathic infertility

Consideration of the most common currently practiced laboratory assays for human spermatozoal fertility are discussed, with reference to the relevance of such assays to success or failure in human in vitro fertilization (IVF). Such IVF therapy should be the definitive challenge for human spermatozoal fertilization ability. However, when fertilization fails, is polyspermic, or is suboptimal, then questions concerning the step or steps in the process of fertilization which are dysfunctional remain unanswered. Quite possibly new assays need to be devised to address these problems, while in the meantime our present laboratory assay systems need to be improved to discern those defects in fertilization which operate in many cases of human idiopathic infertility.

The diagnostic value of seminal adenosine triphosphate (ATP) in an in vitro fertilization (IVF) program

The level of adenosine triphosphate (ATP) was quantitated in semen samples used for in vitro fertilization of human oocytes. Seminal ATP level correlated with the concentration and percentage motility of spermatozoa but not with the in vitro fertilization rate of human oocytes. Seminal ATP measurement appears to have little diagnostic value in predicting the fertilizing capacity of spermatozoa as evaluated by the multivariate stepwise discriminant analysis.

Establishment of TEST-yolk buffer enhanced sperm penetration assay limits for fertile males

TEST-yolk buffer has been shown to enhance sperm penetration of zona-free hamster eggs. Review of sperm penetration assay (SPA) data from a fertile population was undertaken to determine a normal range for SPA with TEST-yolk buffer enhancement. Thirty-eight intrauterine insemination patients and 4 artificial insemination donors who had successfully initiated a pregnancy within 18 months of SPA analysis were examined. All 42 enhanced SPAs demonstrated penetration of greater than 10%, and 37 of these (88%) yielded SPA values of greater than or equal to 20%. Thirty-three percent (14/42) of these individuals achieved 0% penetration in the SPA without TEST-yolk buffer. The SPA performed with the TEST-yolk modification has fewer false negatives than the assay done with the original methodology.

Variation of movement characteristics with washing and capacitation of spermatozoa. II. Multivariate statistical analysis and prediction of sperm penetrating ability

Fifty semen samples were studied by computer-assisted semen analysis before testing in the sperm penetration assay (SPA). Twenty-one concentration and movement measurements were obtained from each sample on sperm in semen, after washing and swim-up, and again after an 18-hour capacitation period. Discriminant analysis was then used to define a function from these measurements that would classify the SPA results as above or below a 10% penetration rate. A significant function was identified using the following variables: sperm concentration and motility in semen, and mean curvilinear velocity, linearity, and amplitude of lateral head displacement of washed sperm. Movement measurements of capacitated spermatozoa were not useful predictors in this analysis. The overall accuracy of this function for predicting SPA results was 72%. These findings demonstrate that computer-derived measurements of sperm movement provide biologically useful information regarding sperm function, and, in addition, emphasize the importance of multivariate techniques in the analysis and description of human sperm motion.

Optimizing the sperm penetration assay with human follicular fluid

Major limitations of the conventional sperm penetration assay are the inability to assess several aspects of sperm function (zona binding and penetration) and the absence of human ovulatory products known to influence fertilization. We therefore modified the sperm penetration assay by the addition of human follicular fluid (FF) to induce the acrosome reaction in an attempt to improve the false-negative rate of the conventional technique. In 26 patients with negative results, results became positive in 20 with human FF and the acrosome reaction increased fourfold. In 19 different men, we compared the results of the conventional and modified assays with outcome of in vitro fertilization. The false-positive rate was the same, but the false-negative rate was reduced from 40% to 7% with the addition of human FF.

Evaluation and treatment of a male factor component to unexplained infertility

The standard semen analysis frequently fails to identify subfertile males even when findings are normal and conversely often fails to identify fertile males with subnormal semen analyses. This has created the need to produce other tests of sperm physiology that will better distinguish a fertile from a subfertile specimen. Understanding more about the nature of the sperm defect should lead to the establishment of more specific and effective therapies. Until that time, it would still be reasonable to try some of the available empirical therapies even though they may work merely by a placebo mechanism.

Hypoosmotic swelling test of sperm

For the diagnosis and evaluation of the therapy for male infertility and for predicting the outcome of AIH and IVF-ET, technically simple, replicable tests that can be performed virtually anywhere and that have definite reliability are required. The results of the HOS test correlate well with the functions of the sperm cell membrane, indicating such aspects as motility, and it is thought to be a particularly effective test of human sperm fertility. Because the HOS test reflects the functions and integrity of the sperm cell membrane, it should be possible to use it to predict the potential for fertilization of frozen sperm.

The long-term predictive value of the zona-free hamster ova sperm penetration assay

Three hundred sixty-nine infertile couples were followed for 2 to 5 years in a study designed to determine the clinical long-term predictive value of the zona-free hamster ova sperm penetration assay (SPA). Semen analysis (SA), SPA, and a full infertility workup were done in all cases, and only couples in whom the female had no evident cause of infertility were included in the study. During the follow-up period, 106 couples (29%) achieved a pregnancy. Sixteen percent of 131 men who had an SPA of 0%, 23% of 120 men with 1% to 19%, and 48% of 118 men who had a penetration of greater than 19% impregnated their wives 2 to 5 years after the assays. Significant difference in fertility prognosis was found between those who had an SPA greater than 19% and those with an SPA less than 20% (48% versus 20%). Sperm penetration assay greater than 19% was predictive of higher pregnancy rates in both oligospermic (41% versus 17%) and unexplained infertile couples (52% versus 24%). The specificity and positive predictive values of the SPA were higher than those of the SA (77% versus 57% and 48% versus 37%). These findings emphasize the value and importance of the SPA in determining the long-term fertility potential of men.

A sperm-zona pellucida binding test and in vitro fertilization

Sperm binding to the zona pellucida was studied in 106 in vitro fertilization (IVF) patients. Oocytes that failed to fertilize in vitro were inseminated with a mixture of equal numbers of test and fertile donor sperm differentially labeled with fluorescein or rhodamine to control for variability in the sperm-zona pellucida binding capacity of oocytes. The ratio of the number of test and control sperm bound to four to six zonae pellucidae was significantly correlated with sperm morphology, viability, motility, motility index, and normal intact acrosomes in semen. The sperm-zona pellucida binding ratio was the most significant factor related to IVF rates by logistic regression analysis. But the proportions of sperm with normal morphology and intact acrosomes in semen also were significant. In patients with less than 30% of sperm with normal morphology, there was a highly significant relationship between IVF rate and sperm-zona pellucida binding and a weaker relationship with sperm morphology. In conclusion, the sperm-zona pellucida binding ratio test is useful for predicting sperm fertilizing ability in vitro, particularly in men with poor sperm morphology.

Modification of the zona-free hamster ova bioassay of boar sperm fertility and correlation with in vivo fertility

These studies were designed to evaluate the ability of the zona-free hamster ova bioassay to detect differences in fertility of boar sperm. In the first study, sperm from two previously infertile boars were compared to sperm from seven previously fertile boars. The percentage of zona-free hamster ova penetrated by sperm from the previously infertile boars was significantly lower than the percentage of ova penetrated by sperm from previously fertile boars (18% of ova penetrated vs. 83%, P less than .001). In the 14 ejaculates from the previously infertile boars that had ejaculate motilities of 50% or greater, the percentage of zona-free hamster ova penetrated continued to be lower than in ejaculates from the fertile boars. One of the two previously infertile boars consistently had a normal semen analysis. The only two observed manifestations of his reduced fertility were his zero conception rate and the limited ability of his sperm to penetrate zona-free hamster ova. In the second study, females were inseminated with equal numbers of sperm from two previously fertile males and the paternity of offspring determined at birth. The experiment was replicated with four combinations of six boars. A high correlation was observed between the percentage of offspring sired and the ability to penetrate zona-free hamster ova (R = .89). Neither morphology nor the ability of the sperm to undergo an acrosome reaction during in vitro incubation was correlated with fertility in the competitive mating situation. These results suggest the zona-free hamster ova bioassay can improve the in vitro fertility assessment of fresh boar semen.

Efficacy of zona-free hamster egg sperm penetration assay as a predictor of in vitro fertilization

The efficacy of the zona-free hamster egg sperm penetration assay (SPA) as a predictor of in vitro fertilization (IVF) is studied. Indications for IVF were tubal factors in 35 couples and male factors in 24 couples. The diagnostic characteristics of SPA in reference to IVF for the whole group (n = 59) were reasonably reliable. Sensitivity was 74%, specificity was 84%, and diagnostic accuracy was 81%. However in patients with male factors, SPA was less reliable in terms of sensitivity (70%), specificity (57%), and diagnostic accuracy (63%), than in patients with tubal factors where the indicators were 80%, 97%, and 94%, respectively. Semen from patients with male infertility shared notable variations in terms of sperm density and motility which may account for the low SPA predictivity. SPA seems to be a useful screening test for prediction of IVF outcome. However other semen variables should be considered before interpretation, especially in male infertility where the diagnostic accuracy is low.

Zona-free hamster egg penetration assay: prognostic indicator in an IVF program

Fertility potential measurements of the zona-free hamster egg bioassay were compared with the in vitro fertilization of human eggs. Sperm from 31 husbands or donors participating in an in vitro fertilization-embryo transfer program was used in 38 simultaneous inseminations of human and hamster eggs. In 7 out of 31 cases, a positive penetration (hamster) test fertility assessment was obtained in the absence of fertilization of the human eggs, attributable to egg immaturity and in one case to equipment failure. In the remaining 30 cases, fertilization was achieved with at least one egg per case. There were no false-negative assessments. Our results indicate that this bioassay is highly correlated with the fertilization of human eggs in vitro.

The sperm penetration assay: can it discriminate between fertile and infertile men?

The sperm penetration assay with zona-free hamster ova is widely used to evaluate male infertility. Despite a growing body of literature about this assay, its results remain difficult to interpret. To evaluate the clinical usefulness of this test, we reviewed the world's literature about this assay and analyzed the test's performance. Its sensitivity ranges from 0.00 to 1.00 and specificity ranges from 0.95 to 1.00 for diagnosing male infertility. For predicting in vitro fertilization failures, its sensitivity varies from 0.00 to 0.78 and specificity ranges from 0.51 to 1.00. The reproducibility of this assay is not clear, and there is little standardization of methods between laboratories. Until the validity and reproducibility of the sperm penetration assay have been established, this expensive test should probably not be used to evaluate infertile couples.

Human sperm penetration assay as an indicator of sperm function in human in vitro fertilization

Performance of spermatozoa in a hamster oocyte/human sperm penetration assay (SPA) was correlated with the results of in vitro fertilization (IVF). Forty-two patients underwent 50 IVF cycles. SPA scores were obtained before IVF cycles (screening SPA, n = 30) and, where practical, on the semen sample used for IVF (IVF SPA, n = 26). Screening SPA score did not correlate to IVF result, fertilization and cleavage rates were similar between normal (n = 17) and low (n = 13) SPA groups, pregnancy rates were 35 and 46%, respectively. In addition, SPA score at the time of IVF did not correlate with IVF result. Pregnancy rates were 33% for the normal group (n = 16) and 30% for the low SPA group (n = 10). Overall, the low SPA group (n = 16) exhibited a 78% fertilization rate and a 38% pregnancy rate, which was not different from the normal SPA group: 76 and 29%, respectively. The results of this study indicate that SPA score is a poor indicator of sperm function in IVF.

Semen parameters and fertilization of human oocytes in vitro: a multivariable analysis

Semen parameters in 195 couples undergoing in vitro fertilization and embryo transfer were studied using multivariable analysis. Semen parameters that correlated most closely with reduced ability to fertilize apparently mature oocytes were a slow rate of foreward progression of sperm and the presence of excess numbers of white cells in semen. In men with semen parameters within the normal range, the hamster egg penetration assay (HEPA) test did not add additional predictive power. In men with suspected semen abnormalities, however, a low attachment rating added some, but minimal, predictive value. None of the predictive methods reported thus far in this or other studies offers sufficient accuracy to reliably identify the men who will prove infertile for in vitro fertilization treatment.

Simultaneous in vitro fertilization and gamete intrafallopian transfer (GIFT)

During a 6-month period, a combination of gamete intrafallopian transfer (GIFT) and in vitro fertilization (IVF) was offered to all couples beginning an IVF treatment cycle in whom the wife had anatomically normal fallopian tubes. It was recommended to these couples that sufficient oocytes be reserved for insemination in vitro to determine whether the husband's spermatozoa could fertilize the wife's oocytes. During this interval, 16 couples underwent the combined IVF-GIFT procedure. All of the IVF-GIFT couples had at least two oocytes inseminated in vitro and at least two oocytes for GIFT. Of the 16 IVF-GIFT couples, only 1 (6.25%) achieved a clinical pregnancy. More important, 50% (8/16) of the IVF-GIFT couples had no oocytes fertilized in vitro. With the information concerning lack of fertilization in vitro, appropriate recommendations concerning future fertility management can be made. If the same couples had undergone the GIFT procedure alone, without additional oocytes fertilized in vitro, this information would not have been obtained.

The in vitro fertilization of supernumerary oocytes in a gamete intrafallopian transfer program

Gamete intrafallopian transfer (GIFT) was performed on a series of 42 couples in whom four oocytes were replaced into the fallopian tubes and the remaining oocytes were inseminated with 100,000 motile spermatozoa. Fertilization in vitro was assessed 16 to 20 hours later. An overall pregnancy rate after GIFT of 40.0% (12/30) in normospermic couples and 16.7% (2/12) in oligospermic couples was seen. Supernumerary oocytes were submitted to in vitro fertilization (IVF) and the findings related to the likelihood of pregnancy. No correlation between IVF and the likelihood of GIFT pregnancies was found in either the oligospermic or normospermic couples. A similar proportion of pregnancies was seen in couples with or without evidence of fertilization of the supernumerary oocytes in both the oligospermic and normospermic couples. However, a high proportion of normospermic couples with no evidence of fertilization had only one oocyte remaining for insemination. These results suggest that the failure of low numbers of supernumerary oocytes to fertilize in vitro after GIFT relates to oocyte selection criteria and does not mean a reduced chance of conception in that treatment cycle.

Correlation between in vitro fertilization and human sperm density and motility

The conventional sperm characteristics of density (millions per milliliter) and motility, scored in a semi-subjective way, were correlated with results of an on-going in vitro fertilization and embryo transfer program. No male infertility patients were included in this study. Individual characteristics of the "successful" ejaculates are described. Sperm densities in the original ejaculate of more than 10 X 10(6) spermatozoa/ml did not significantly improve outcome (P less than 0.01). In contrast, sperm motility seemed to play the most important role, since most pregnancies (12/14) occurred using sperm samples with greater than or equal to 60% total motility (P less than 0.001). The incidence of multipronuclear fertilization is also described and discussed. These data, which were collected during 1984 in the in vitro fertilization unit of Professor R. Schoysman and coworkers (Vilvoorde, Brussels), may help to make fertilization in vitro and embryo transfer a viable method in cases of mild male subfertility, and to provide guidance in preparing some couples for the combined use of husband and donor semen if a sufficient number of oocytes are obtained.

In vitro behavior of human nonfertile semen in isoosmotic and hyperosmotic media

High-ionic-strength media are known to favor rapid capacitation and acrosome reaction of spermatozoa in vitro. The influence of isoosmolar (N-BWW) and hyperosmolar (H-BWW) media on the percent motility, forward progression, and zona-free hamster egg penetration has been investigated for 148 semen from patients consulting for male or idiopathic sterility. After 15 h of incubation, the hyperosmotic medium had no significant detrimental effect on the percent motility of spermatozoa, although the forward progression was better maintained in the isoosmolar medium. In general egg penetration was increased when spermatozoa were treated with the hypertonic medium, and in particular 5 patients whose semen showed no penetration when treated with N-BWW scored greater than 12% when treated with H-BWW. For the 23 subjects who had an IVF at the same period, a good agreement with zona-free egg penetration was found in 70% of the cases.

Cryopreservation of hamster oocytes: effects of vitrification or freezing on human sperm penetration of zona-free hamster oocytes

Three experiments were conducted for evaluation of the efficacy of conventional freezing or vitrification of hamster oocytes for use in a human sperm penetration assay (hSPA). In experiment 1, oocytes were cryopreserved and evaluated for survival on the basis of morphologic criteria. Survival of vitrified oocytes and that of frozen oocytes were not different, whereas all cryopreserved groups had lower survival than noncryopreserved controls. In experiment 2, oocytes were conventionally frozen or vitrified and evaluated in an hSPA. Vitrified oocytes had a lower frequency of sperm penetration than frozen oocytes, and all cryopreserved groups had lower penetration rates than untreated controls. In experiment 3, oocytes were exposed to the cryoprotectant used to vitrify (VS1) or freeze (DMSO) but not cooled prior to evaluation in an hSPA. Exposure to DMSO but not VS1 reduced hSPA values. It is concluded from these experiments that while all cryopreserved oocytes do not survive, at current stages of development conventionally frozen oocytes perform better than vitrified oocytes in the hSPA and losses associated with conventional freezing procedures may be related to cryoprotectant exposure, whereas vitrification losses are more probably due to events associated with rapid cooling and/or warming of the oocytes.