Reliability and accuracy of the zona-free hamster ova assay in the assessment of male fertility

The hypo-osmotic swelling test: Is it a sperm vitality or a viability assay?

The first two editions of the World Health Organization laboratory manual described the determination of live spermatozoa by a dye exclusion method as a sperm "viability" test, whereas subsequent editions classified it as a "vitality" test, without providing an explanation for the reclassification. Additionally, the hypo-osmotic swelling (HOS) test, which assesses the functional integrity of the human sperm membrane, was placed in the same category as the dye exclusion test. Although the two terms might seem synonymous, the term "vitality" merely means "alive," whereas "viability" assesses qualities or physiological functions of a living entity. After comparing the morphological, physiological, and clinical findings obtained from dye exclusion testing vs. the HOS test, we conclude that the HOS test should be classified as a viability test, not merely as a vitality test.

Evaluation of sperm cryoprotective media in respect to fertilizing capacity tested in vitro

Nine different cryoprotectant buffers were tested to measure their protective ability towards main sperm seminological parameters. These were: maintained sperm motility, progressive motility and sperm viability. Out of the nine tested buffers, medium E (TES-Tris without glycerol) and H (glycerol only) showed significantly lower (P < 0.001) values than the rest of the studied buffers in respect to all tested seminological features. The other media did not differ significantly in their cryoprotective abilities to sperm. Richardson's medium (A) preserved sperm viability significantly better (P < 0.001) than the other tested buffers, reaching 63.1% of viable spermatozoa in proportion to the fresh sperm sample before freezing. Three cryoprotectants, A (with egg yolk, no TEST buffer system), D (neither egg yolk nor TEST buffer system), F (TEST-egg yolk buffer system) were further studied for their ability to preserve sperm function in sperm-cervical mucus penetration (Penetrak) and sperm penetration assay (SPA). In our hands, neither supplementation of the buffer with egg yolk nor TEST-egg yolk buffer system promoted sperm capacity in functional tests. A,D,F buffers did not significantly differ among each other in applied functional assays, however, they all diminished (P < 0.001) sperm penetration ratios when compared with fresh sperm samples. Therefore enhancement of sperm capacity to fertilize after equilibration with TEST-egg yolk buffer system should be contested.

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.

Influence of incubation time/temperature on acrosome reaction/sperm penetration assay

The acrosomal status of human spermatozoa was studied in relation to the score of the sperm penetration assay (SPA) at low-temperature (4 degrees C) incubation for induction and synchronization of the acrosome reaction (AR) and the incubation time of spermatozoa in conventional SPA. Spermatozoa were collected from 18 patients, selected by the "swim-up" method and treated in three different ways: (1) short-term incubation group (SIG): 3 h incubation at 37 degrees C, and (2) long-term incubation group (LIG): 20 h incubation at 37 degrees C, and (3) low temperature group (LTG): 24 h incubation at 4 degrees C followed by additional incubation at 37 degrees C for 3 h. The conventional methods of incubation, i.e. SIG (3 h) and LIG (20 h) did not show any significant differences as evaluated by the sperm penetration rate and the number of decondensing sperm heads per oocyte. In contrast, in the LTG all parameters were significantly increased, especially those of penetration rate (p less than 0.0005) and decondensing sperm heads per oocyte (p less than 0.0005). The percentage of AR significantly increased (p less than 0.0005) in the LTG (14.7%) compared with SIG (6.1%) and LIG (10.6%). A significant correlation was demonstrated between AR and the parameters used for evaluation of the SPA. The penetration rate (Spearman test, r = 0.462, n = 54, p less than 0.003) was the most significant parameter correlated with AR. It would appear that only human spermatozoa having completed AR are capable of fusing with the zona-free hamster ova.(ABSTRACT TRUNCATED AT 250 WORDS)

Factors affecting penetration of zona-free hamster ova

The sperm penetration assay is an expensive, time-consuming test to assess male fertility in vitro. Although some investigators are enthusiastic in its application, others feel that it is not sensitive or specific enough to be used as part of the routine infertility evaluation. Indeed, this bioassay is not a faithful reproduction of in vivo conditions. However, if the SPA is abnormal, it is unlikely that sperm will fertilize a human ovum in vivo. Conversely, a normal SPA does not guarantee successful in vivo fertilization. No bioassay can be absolute in its predictive value, but false-negative results must be kept to a minimum for this bioassay to be of any clinical significance. Each laboratory performing the SPA should optimize the assay for sensitivity, reproducibility, and minimization of false-negative results and then establish normal and abnormal ranges of its own. If the limitations of the SPA are kept in mind, and if we employ it very selectively, it may still be useful.

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.

Pretreatment of sperm with human follicular fluid for borderline male infertility

To test the usefulness of human follicular fluid (FF) in treating male infertility, we incubated washed sperm specimens from 31 couples undergoing intrauterine insemination (IUI), for male and/or unexplained infertility, with either FF or Ham's F-10 medium (Gibco, Grand Island, NY), in alternating cycles in a randomized manner. Semen specimens from 28 men were incubated with either medium or FF. Incubations with FF have increased sperm penetration assay (SPA) scores from 24.8 +/- 17.3 to 34.3 +/- 13.6 (P less than 0.01). Incubation with heat-inactivized FF also has increased SPA scores, although to a lesser extent than noninactivized FF. Seventeen pregnancies occurred in the 31 couples treated by IUI (54.8%), 16 of them in FF-treated cycles (51.6%) and one in "control" IUI cycles (3.2%, P less than 0.01). All pregnancies occurred within four treatment cycles. Thus, IUI after sperm wash and preincubation with FF may be suggested for four to six cycles to couples with male factor and/or unexplained infertility who are reluctant to resort to artificial insemination by donor or adoption, before attempting the more costly and complex in vitro fertilization-embryo transfer procedure.

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.

Hypoosmotic swelling test in the prediction of male fertility

The hypoosmotic swelling test (HOS) is a simple test to measure the functional competence of human sperm membranes. The question is, does a relationship exist between this competence and the fertilization potential of human spermatozoa? In this study the strongest correlation (r = 0.76) was obtained between sperm swelling and sperm viability (supravital staining). Only a moderate correlation (r = 0.50) was obtained with normal sperm morphology; weaker correlations were also obtained with the sperm penetration assay (r = 0.42) and human IVF (r = 0.24). The results, therefore, indicate that the HOS test has a limited predictive value. Notwithstanding this low concordance between sperm swelling and fertilizing potential, a less than 50% HOS test threshold was seen to be a definite indicator of a male factor.

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.

Usefulness of sperm penetration assay in fertility predictions

The competence of the sperm penetration assay (SPA) to predict male fertility, as determined by normal sperm morphology and the fertilizing potential, as shown by human in vitro fertilization (IVF), was investigated. A significant correlation was obtained between normal sperm morphology and the SPA (phi = 0.623). A weaker correlation was however obtained with human IVF (phi = 0.397). Notwithstanding this weak association, a positive SPA (greater than 10%) was highly predictive (95%) of human IVF success. In contrast, a negative SPA (less than or equal to 10%) was associated with a high rate of false-negatives (65%). The SPA does however warn that a male factor may be present, as the mean fertilization rate of this group of patients was markedly reduced. The preincubation period for the spermatozoa did not play a major role in the predictive ability of a SPA outcome.

Acrosome reaction of human spermatozoa in zona-free hamster egg penetration test

The acrosomal status of human sperm during preparation for the process of zona-free hamster egg penetration test (ZFHEPT) was determined. The incidence of acrosome reaction (AR), as assessed by triple-stain technique, was significantly increased after 24 hours of incubation at 4 degrees C in TES-Tris (TEST)-yolk buffer, but the absolute values were relatively low (20% or less). Sperm from fertile donors and infertile patients with normal or abnormal semen analysis displayed similar capacity to undergo the AR in vitro. Although a positive correlation was found between the incidence of AR and the score of ZFHEPT, a remarkable individual variation was noted. The incidence of AR in freely swimming human sperm does not accurately reflect the fertilizing ability of the sperm.

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.

The relationship between sperm chromosomal abnormalities and sperm morphology in humans

It has been suggested that an assay for sperm morphology might prove useful as an initial screen in evaluating men at risk for an increased frequency of sperm chromosomal abnormalities. In this study, the technique for analysis of human sperm chromosomes after penetration of hamster eggs was employed to determine whether there is an association between the frequency of chromosomally and morphologically abnormal sperm. 30 healthy men of proven fertility were studied. The ages of the donors ranged from 22 to 55 years. The analysis was performed "blindly" so that the technician analysing the chromosome spreads had no knowledge of the age of the donors or of the individual frequencies of morphologically abnormal sperm. There was no significant relationship between the proportion of morphologically abnormal sperm and the proportion of chromosomally abnormal sperm when controlled for age. This was true for the total frequency of chromosomal abnormalities and also for numerical and structural chromosomal abnormalities. These results suggest that an assay of morphology is not a good indication of chromosomal normality in human sperm.

The human sperm-hamster egg penetration assay: prognostic value

Males from 227 infertile couples were evaluated using the human sperm-hamster egg penetration assay (SPA). Indications for the SPA were abnormal semen analyses, poor postcoital tests, documented autologous sperm antibodies, and long-term unexplained infertility. Normal results defined as greater than or equal to 11% penetration were seen in 58.6% of couples. Penetration rates of 1% to 10% were observed in 25.6%, and 15.9% failed to penetrate any of the oocytes. During the follow-up period, with a mean of 17.9 months, 26.9% conceived at least once with or without treatment. Monthly fecundity was 0.014 for normal SPA patients and 0.007 for the abnormal SPA group when calculated by the Kaplan-Meier survival curve with Cox correction for unequal follow-up. The monthly fecundity rate at any time during the 30-month interval of follow-up was twice as great for men with normal SPA values as for those with abnormal values, regardless of male or female diagnosis or therapy indicating the prognostic value of the SPA in an infertile population.

Acridine orange fluorescence as male fertility test

Acridine orange fluorescence, semen analysis, and zona-free hamster egg penetration tests were performed on 100 consecutive semen samples. No significant correlation was detected between sperm motility and red fluorescence. However, abnormal sperm morphology correlated significantly with red fluorescence (p less than or equal to 0.001) and fluorescence index (p less than or equal to 0.001). Presence of a high percentage of red fluorescing sperm did not prevent their penetration of zona-free hamster egg, indicating that the presence of abnormal DNA had no effect on the sperm fertility. The significance of acridine orange fluorescence male fertility test requires further elucidation.

Sulfasalazine-induced abnormal sperm penetration assay reversed on changing to 5-aminosalicylic acid enemas

Sulfasalazine, a drug used in the treatment of inflammatory bowel disease, has been associated with male infertility, an effect attributed to sulfapyridine rather than to 5-aminosalicylic acid (5-ASA), the presumed therapeutically active component of sulfasalazine. Recently, the sperm penetration assay (SPA) has been found to be an accurate method of quantitating male fertilization potential. We report the case of a man with ulcerative colitis in whom infertility and a markedly abnormal SPA were demonstrated while he was taking sulfasalazine. Shortly after discontinuing sulfasalazine and initiating treatment with 5-ASA enemas, his SPA became normal and his wife became pregnant. The SPA is a useful screening test for sulfasalazine-induced male infertility. On the other hand, 5-ASA enemas do not appear to be associated with an abnormal SPA.

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.

Relationship between the sperm penetration assay and other tests of sperm function

Semen from 88 men of infertile couples and 33 fertile donors differed in seminal fluid analysis (sperm density and motility) (SFA) as well as in the penetration of hamster ova (SPA) and bovine cervical mucus (MPT). In the fertile group, significantly more subjects had adequate SFA, SPA, or MPT results than in the infertile group. When the two groups were subdivided into those with normal or those with abnormal SFA, no differences were noted in SPA, MPT, or postcoital test (PCT) scores. The SFA parameter most consistently reflected in the results of the SPA, MPT, and PCT was sperm density. This was most evident when the SFA was poor. The worst prognosticator of fertility was the SFA, with 30% of the fertile donors having an abnormal SFA. The worst prognosticator of infertility was the MPT, with 79% of the patients penetrating in the fertile range. The SPA was a significantly better predictor than either the SFA or MPT. SPA and MPT results were positively correlated only in the overall infertile group. The SPA, MPT, and PCT measure sperm qualities distinct from those revealed by the SFA, and from each other, and in combination provide the best assessment of fertility.

Sperm viability: a comparison of analytical methods

Two methods of measuring human sperm viability, the stain exclusion assay and the hypoosmotic swelling (HOS) test, were evaluated. Human sperm were pretreated with 2.0% glutaraldehyde or 0.1% Triton X-100 and compared to untreated controls. Approximately one half of the sperm were found to be viable in the control samples and nearly all sperm were non-viable in the Triton X-100 treated samples by both the stain exclusion and HOS assays. After glutaraldehyde pretreatment, presumably inactivating the spermatozoa, the HOS test revealed that most sperm were not viable, while the stain exclusion test found no difference between glutaraldehyde pretreated sperm and control sperm. Investigations with scanning and transmission electron microscopy demonstrated that the HOS test caused the membrane of the sperm tail to swell and the tail fibers to coil several times within the swollen membrane. It is concluded that the stain exclusion assay merely measures the structural integrity of the sperm membrane, whereas the HOS test also provides an indication of the physiological integrity of the sperm membrane.

Influence of the concentration of motile sperm inseminated on the ovum penetration assay results: toward a standardized method

The influence of the concentration of motile sperm inseminated on the zona-free hamster egg penetration rate has been studied. In 3 fertile men, the higher the concentration of motile sperm inseminated, the higher the ovum penetration rate. This correlation emphasizes the usefulness of standardizing the technical conditions under which the ovum penetration assay is performed. It is also suggested to refer to a standard curve for results analysis. In the 22 patients studied, the outcome of the heterologous ovum assay was in most cases related to the initial sperm parameters. However, some disagreement was also observed. In the absence of a correlation between the initial sperm parameters and the ovum penetration rates, further investigation is needed in order to either more precisely determine the aetiology of unexplained couple infertility, or, in case of intrauterine insemination or in vitro fertilization, to better understand the conditions under which spermatozoa are capacitated in vitro.

Comparison of the penetration ability of human spermatozoa into bovine cervical mucus and zona-free hamster eggs

In vitro bovine cervical mucus (BCM) penetration tests, sperm penetration assays (SPA) using zona-free hamster eggs, and routine semen analyses were performed on a total of 136 freshly collected semen samples from men who were seen at an infertility clinic. The correlations between bovine cervical mucus penetration and other semen parameters were the percent motile spermatozoa (r = 0.48), progressive motility grade (r = 0.44), sperm count (X 10(6)/ml) (r = 0.47), the percent normal morphology (r = 0.32) and the percent eggs penetrated (r = 0.46) (P less than 0.0001 for each correlation coefficient). When known fertile (n = 32) and infertile (n = 18) groups were tested, positive mucus penetration was associated 75% correctly and positive egg penetration was associated 90% correctly to clinical status. The mucus test had no false-negative results and the SPA had no false-positive results in these groups. It appears, then, that the mucus test and sperm penetration assay, although contributing different elements of data to an infertility evaluation, are both useful adjuncts to a semen analysis.

The zona-free hamster egg penetration assay as a prognostic indicator in a human in vitro fertilization program

The present study was designed to test the validity of the hamster egg penetration assay as a prognostic indicator of male fertility in 54 patients undergoing in vitro fertilization. Human oocyte fertilization, cleavage, and pregnancy were compared with the results of this bioassay. Good correlation was found between hamster egg penetration and oocyte fertilization. Conversely, a definite lower limit of hamster egg penetration to define absolute male infertility could not be established because human oocyte fertilization, cleavage, and even pregnancy occurred in spite of low hamster egg penetration.

Zona-free hamster egg-sperm penetration assay: II. Correlative study with routine semen analysis

This work studied the effect of variations in the different parameters of routine semen analysis on the penetration rate of the spermatozoa into the zona-free hamster eggs, using semen samples from 21 fertile donors, 57 infertile patients with normal spermiograms, 63 infertile patients with subnormal spermiograms, and 19 frozen semen samples. The results of the hamster test do not correlate with the percentage of motile spermatozoa, the percentage of live spermatozoa, or the percentage of spermatozoa with normal morphology in the semen samples. A positive correlation was found between the results of the hamster test and three other parameters of the semen analysis: the sperm concentration, the progressive type of motility, and a pH range of 7.2-7.7, but these positive correlations were statistically insignificant.

Zona-free hamster egg-sperm penetration assay: I. Testing of human semen fertilizability

The zona-free hamster egg penetration test was performed on semen samples from 21 fertile donors, 57 infertile patients with normal semen parameters, and 63 infertile patients with subnormal spermiogram, as well as on 19 frozen semen samples. In the donor group 100% of the samples gave a positive range of penetration (PRP) of 20-96% with a mean penetration rate (MPR) of 53%, while 84% of the frozen samples showed a PRP of 18-44% and an MPR of 31%. Although 74% of the samples from infertile patients with normal spermiograms gave a PRP of 11-92% and an MPR of 34%, only 46% of the semen samples from the infertile patients with subnormal spermiogram showed a PRP of 21-100% but an MRP of 43%.

The limitations of in vitro fertilization from males with severe oligospermia and abnormal sperm morphology

Thirty-one patients whose infertility was attributed to oligospermia were included for treatment by in vitro fertilization and embryo transfer. Three subgroups were defined: severe oligospermia (less than or equal to 5 million motile sperm/ml), moderate oligospermia (6 to less than 12 million motile sperm/ml), and abnormal sperm morphology (greater than 60% atypical). The fertilization rates were compared to those of a normospermic group managed concurrently. A modified overlay technique of sperm preparation is described for oligospermic samples so that the number of motile spermatozoa inseminated into each tube or culture dish containing a mature preovulatory oocyte was similar in each category, within the range 0.5 to 2 X 10(5)/ml. Significantly fewer oocytes were fertilized in the severe oligospermic group (P less than 0.001), suggesting a reduced capacity for fertilization by spermatozoa from severely oligospermic males. The fertilization rate of oocytes was normal in the moderate oligospermic group and those with abnormal morphology, although in the latter there was a significant delay noted in reaching the pronuclear stage (P less than 0.001), and the embryos were at a less advanced stage of cleavage at the time of transfer (0.001 less than P less than 0.01). Pregnancies were achieved in both the severe and the moderate oligospermic groups, with healthy infants delivered from each.

The relationship of tubal blockage, infertility of unknown cause, suspected male infertility, and endometriosis to success of in vitro fertilization and embryo transfer

The success of in vitro fertilization (IVF) and embryo transfer has been examined with regard to five categories of infertility over a 2-year period. Fertilization rates in vitro were highest in women with bilateral tubal blockage and women treated for endometriosis. There was a significant reduction of approximately 13% in the fertilization rate of couples with idiopathic infertility and women who had failed to conceive after 12 cycles of artificial insemination by donor. A further substantial reduction in the fertilization rate occurred when the husband had low quality semen, particularly when no abnormality was detected in the wife. Repeated IVF in couples with idiopathic infertility eventually resulted in fertilization. It is recommended that donor spermatozoa not be used for cases of idiopathic infertility, but it may be needed in cases of poor semen quality. There were no differences in the pregnancy rates following embryo replacement in any of the groups studied, nor was there any detectable effect of age on fertilization or pregnancy rates up to the age of 44 years.