The sperm penetration assay: its usefulness reevaluated

The role of sperm creatine kinase in the assessment of male fertility

The lack of reliable methods to assess sperm fertilizing potential has been a long-standing problem for infertile couples and for their physicians. The most widely used tests, the measurements of sperm concentrations, motility, velocity and morphology in the ejaculate, are of limited utility. Indeed, following intrauterine insemination, a treatment that compensates for low motile sperm concentrations, there were no significant differences found in semen parameters among those who did or did not achieve pregnancies. Other available assays probing for selected sperm functions, such as membrane integrity, acrosome enzyme activity, bovine cervical mucus penetration test, zona-free hamster oocyte penetration test and sperm binding to various carbohydrates,10–13 have all failed thus far to consistently predict male fertility. It became increasingly obvious that there was a need to identify cellular markers of sperm quality and fertilizing potential.

Levels of P34H, a sperm protein of epididymal origin, as a predictor of conventional in vitro fertilization outcome

A prospective double-blind study was performed to determine if Western blot detection of P34H, a sperm protein of epididymal origin that is involved in the binding to the zona pellucida, is predictive of standard IVF outcome. Our results demonstrate that the proportion of positive P34H cases that produced embryos in vitro clearly differs from cases with undetectable levels of P34H (P<.001).

The relationship of porcine sperm zona-binding ability to fertility

Several laboratory assays have been designed to assess the fertility potential of a semen sample before insemination, but none have been consistent and accurate predictors of fertility. To determine whether zona-binding ability may be a useful fertility predictor, we validated and used an in vitro competitive assay to measure the ability of porcine sperm to bind to the zona pellucida. The zona-binding ability of sperm from 11 boars that exhibited a broad range in average litter size and farrowing rate was determined. Sperm from each boar were compared directly with sperm from eight other boars in a systematic, pairwise fashion. Sperm from two semen samples were labeled with fluorophores at concentrations that did not affect motility or zona-binding ability. An equal number of labeled sperm from each boar was coincubated with homologous oocytes. Least squares means from analysis of variance were used to rank boars based on zona-binding ability. The competitive assay was effective in establishing a ranking of the boars (R2 = 0.62). Furthermore, there was a correlation between zona-binding ability and fertility when estimated by average litter size (r = 0.64, P < 0.05) but not when estimated by farrowing rate (r = -0.28). The explanation for this difference was that litter size and farrowing rate were poorly correlated (r = 0.14). In conclusion, a competitive zona-binding assay distinguished boars that sired either small or large litters. Competitive zona-binding ability may be useful for identifying boars with reduced fertility that produce smaller litters following insemination.

Evaluation of acrosome reactivity using the Acrobeads test in varicocele patients: findings before and after treatment

The Acrobeads test was performed on semen samples from 43 patients with varicocele before and after varicocelectomy. Sperm motility significantly increased after surgery (p <.05), while sperm concentration and motile sperm concentration did not alter postoperatively. Sperm motion analysis using CellSoft 3000 did not demonstrate a significant change after treatment. Acrobeads score significantly increased after the procedure (p<.005). Pregnancy was achieved in 10 patients (28%). Acrobeads score in cases that achieved pregnancy was increased postoperatively (p<.005). The percentage of patients with a postoperative increase in Acrobeads score in the group that achieved pregnancy was significantly higher than that observed in the unsuccessful group (p <.05). Sperm parameters other than the Acrobeads score did not show a significant difference between the successful and unsuccessful patients. The Acrobeads test assessed postoperatively can be useful in precisely evaluating fertility potential after varicocele repair.

Unresolved Issues in Mammalian Fertilization

This review considers the role of the sperm in fertilization, addressing areas of misunderstanding and unfounded assumptions and taking particular advantage of the large body of data resulting from work with rodent species in vitro. Considerable attention is given to the appropriate use and interpretation of assays for capacitation, acrosomal exocytosis, hyperactivation, and sperm protein phosphorylation, as well as tests for sperm-zona and sperm-oocyte membrane interactions. The lack of general agreement on the means of sperm adhesion to and penetration of the zona pellucida is addressed, and the need for new approaches to this problem is pointed out. Some molecular advances in our understanding of specific steps in the process of fertilization are discussed in the context of intact cell-matrix and cell-cell interaction. This review should provide practical information for researchers just beginning the study of fertilization and interesting but not widely known observations to stimulate new ideas in experienced scientists.

Progesterone Receptor as an Indicator of Sperm Function

Expression of progesterone receptor (PR) localization on spermatozoa was determined in men with normal and abnormal spermiograms. Studies were also carried out to evaluate the potential of PR as a marker of sperm function. Progesterone receptor expression on spermatozoa from men with normozoospermia (n = 8), oligozoospermia (n = 7), asthenozoospermia (n = 8), oligoasthenozoospermia (n = 7), and teratozoospermia (n = 11) was analyzed using an immunocytochemical method with monoclonal antibodies against PR, and flow cytometry using a cell-impermeable fluorescein-tagged progesterone coupled to BSA complex (P-FITC-BSA). Both methods revealed significantly fewer (P < 0.05) PR-positive spermatozoa in men with oligozoospermia, asthenozoospermia, oligoasthenozoospermia, and teratozoospermia compared with men with normozoospermia, thereby suggesting that down-regulation of PR expression in spermatozoa may be one of the causes of male infertility. Spermatozoa from men with normozoospermia (n = 12), oligozoospermia (n = 12), asthenozoospermia (n = 12), oligoasthenozoospermia (n = 9), and teratozoospermia (n = 10) were exposed to low osmotic conditions in the hypoosmotic swelling (HOS) test and then analyzed for PR expression using P-FITC-BSA complex. A significantly higher percentage (P < 0.05) of spermatozoa with physiologically active plasma membrane (HOS+) lacked PR expression (HOS+PR-) in all categories of men with infertility, thereby suggesting that compared to the HOS test, PR expression is a better indicator of sperm function. Furthermore, PR expression in spermatozoa showed a strong (P < 0.05) positive correlation with their ability to undergo an in vitro acrosome reaction. This was observed in all study groups (i.e., normozoospermia, r = 0.8545; oligozoospermia, r = 0.8711; asthenozoospermia, r = 0.7645; oligoasthenozoospermia, r = 0.9003; and teratozoospermia, r = 0.8676). This suggests a potential role for PR in the events leading to the acrosome reaction in sperm.

Induction of the acrosome reaction and zona-free hamster oocyte penetration by a bull with complete teratospermia versus a half brother with normal sperm

A fertile bull producing normal sperm and a sterile half brother exhibiting 100% teratospermia were available to study an induced sperm acrosome reaction and oocyte penetration. Pedigree analysis indicated that this condition was inherited. Experiments were undertaken to study the induction of the acrosome reaction using dilaurylphosphatidylcholine (PC12) liposomes, because this procedure was previously established to be highly correlated with bull fertility. The sperm from each bull were incubated with several PC12 concentrations for varying time periods. The initial percentages of sperm from the sterile bull with intact, partially intact, and lost acrosomes were 67%, 18%, and 14%, respectively, vs 82%, 13%, and 5% for the fertile bull (P < .05). After incubation for 15 minutes with 50 microM PC12 liposomes the corresponding values were, respectively, 51%, 26%, and 19%; and 60%, 28%, and 12%. Thus, the differences after induction of the acrosome reaction, although significant (P < .05), were small. The number of sperm adhered to each oocyte averaged 22 and 10, respectively, for the fertile and sterile bulls, whereas 74% of the fertile bull sperm and only 11% of the sterile bull sperm penetrated oocytes. Mixing the sperm-oocyte complex during incubation and increasing the sperm concentration during incubation to compensate for differences in sperm motility did not markedly affect oocyte penetration by teratogenic sperm, which is consistent with this bull being sterile. In other studies, microinjection of this type of sperm was demonstrated to induce fertilization, so the consequences of using sperm with hereditary defects in assisted reproductive programs to overcome human male sterility may be a concern.

The search is on: finding accurate molecular markers of male fertility

Diagnosis of the fertility potential of a semen sample is essential for consistently high reproductive efficiency. The use of subfertile or infertile semen can have devastating consequences for those selling or using the semen. Therefore it is crucial to develop and use accurate diagnostic tests to determine the fertility of males and of individual semen samples. These diagnostic tests must be economically practical and provide consistent results. The goal of this review is to explore areas of fertility diagnostic research, including what we have termed functional and molecular tests, and consider the accuracy of each test. In this article, literature from several species is cited, and it is noteworthy that each diagnostic test may not be valuable in all species. Multiple functional and molecular tests will likely be needed to effectively characterize male fertility in each species.

Semen analysis at the turn of the century: an evaluation of potential uses of new sperm function assays

Semen analysis is a critical assay in the evaluation of infertility and may yield critical information regarding the etiology and prognosis of many types of reduced male fertility. However, basic semen analysis does not directly measure sperm fertilizing capacity, or many of the biochemical events both prior to and subsequent to fertilization. In the last two decades numerous assays of sperm function have been developed. These assays can be classified as: 1) Assays of general biochemistry and ultrastructure, 2) Assays of zona binding and oocyte penetration, and 3) Assays of postpenetration events. Sperm function assays not only allow an accurate diagnosis of many infertilities not diagnosed by the semen analysis, but can also lead to improved treatment modalities. In this review, basic semen analysis and many sperm function assays are briefly reviewed. Novel uses of sperm function are demonstrated in brief case studies.

A technique for the evaluation of sperm penetrating ability and quality of bovine semen processed in an extender made with Brackett-Oliphant medium and egg yolk

Egg yolk-sodium citrate (EYC) semen extender was compared with an extender made of Brackett-Oliphant medium and egg yolk (BOEY). Ejaculates were divided into equal portions, processed and frozen. Semen was thawed and evaluated for quality. Additional semen was thawed, stained with Hoechst 33342 and the spermatozoa capacitated, after which they were co-incubated with zona-free hamster oocytes to determine their penetrating ability. Sperm penetration of non-compressed, unfixed oocytes was evaluated using an optical sectioning technique on a standard research microscope. Sperm penetration was considered successful if a fluorescing sperm head was observed within the living oocyte in a hanging drop of fertilization medium. There were small differences in percentage of secondary abnormalities and percentage of progressive motility immediately after thawing between spermatozoa extended in EYC or BOEY diluent. There were no differences due to by extender composition in percentage of spermatozoa with intact acrosomes or percent of progressively motile after a 3 h incubation at 37 degrees C, nor the percentage of spermatozoa with head abnormalities. While there were significant correlations between all seminal quality characteristics, no quality measurements were correlated to percentage of oocyte penetration. The new penetration evaluation method allowed for examination of the fertilized oocytes using fluorescent microscopy initially and again after re-incubation for further development.

An alternative medicine study of herbal effects on the penetration of zona-free hamster oocytes and the integrity of sperm deoxyribonucleic acid

OBJECTIVE

To analyze the effects of certain herbs on sperm DNA and on the fertilization process.

DESIGN

Prospective comparative study.

SETTING

Clinical and academic research environment.

PATIENT(S)

Donor sperm specimens.

INTERVENTION(S)

Zona-free hamster oocytes were incubated for 1 hour in saw palmetto (Serenoa repens), echinacea purpura, ginkgo biloba, St. John's wort (Hypericum perforatum), or control medium before sperm-oocyte interaction. The DNA of herb-treated sperm was analyzed with denaturing gradient gel electrophoresis.

MAIN OUTCOME MEASURE(S)

Oocyte penetration and integrity of the sperm BRCAI exon 11 gene.

RESULT(S)

Pretreatment of oocytes with 0.6 mg/mL of St. John's wort resulted in zero penetration. A lower concentration (0.06 mg/mL) had no effect. High concentrations of echinacea and ginkgo also resulted in reduced oocyte penetration. Exposure of sperm to echinacea purpura and St. John's wort resulted in DNA denaturation. In contrast, saw palmetto and ginkgo had no effect. Sperm exposed to 0.6 mg/mL of St. John's wort showed mutation of the BRCA1 exon 11 gene.

CONCLUSION(S)

High concentrations of St. John's wort, echinacea, and ginkgo had adverse effects on oocytes. Saw palmetto had no effect. The data suggested that St. John's wort, ginkgo, and echinacea at high concentrations damage reproductive cells. St. John's wort was mutagenic to sperm cells.

Is intracytoplasmic sperm injection necessary for couples undergoing in vitro fertilization-embryo transfer with normal semen analyses but failing hamster egg penetration assays?

PURPOSE

Our purpose was to assess whether in vitro fertilization (IVF)-embryo transfer (ET) candidate couples with basically normal semen analyses but failing zona-free hamster egg penetration assay (HEPA) scores benefit from intracytoplasmic sperm injection (ICSI).

METHODS

Twenty consecutive IVF candidate couples with normal-borderline semen analyses and failing HEPA scores were recruited. Mature oocytes obtained from each woman were randomly divided between ICSI (group I; n = 126 oocytes) and standard insemination techniques (group II; 138 oocytes). Fertilization (two pronuclei) and cleavage (2-4 cells) rates were assessed for both groups.

RESULTS

There were no statistically significant differences between the two groups with respect to (mean +/- standard error of the mean) fertilization (group I, 63.1 +/- 7.75; group II, 77.8 +/- 4.7%) or cleavage (group I, 87.3 +/- 2.4%; group II, 91.2 +/- 3.5%) rates.

CONCLUSIONS

ICSI is not beneficial for IVF-ET when sperm samples demonstrate a failing HEPA score but have normal or minimally compromised semen analysis parameters.

Antibiotics: effect on cryopreserved-thawed human sperm motility in vitro

OBJECTIVE

To analyze the motility and fertilizing capacity of sperm treated with different antibiotics.

DESIGN

Prospective comparative study.

SETTING

Clinical and academic research environment.

PATIENT(S)

Pooled cryopreserved donor sperm (n = 14).

INTERVENTION(S)

Sperm were washed with Percoll and resuspended in HEPES-buffered human tubal fluid medium containing either amoxicillin, ofloxacin, ciprofloxacin hydrochloride, nitrofurantoin monohydrate, doxycycline hyclate, cefuroxime axetil, or control medium.

MAIN OUTCOME MEASURE(S)

Sperm kinematic and fertilizing parameters.

RESULT(S)

Sperm hyperactivation was decreased in physiologic concentrations of ciprofloxacin hydrochloride and doxycycline hyclate over the course of 48 hours. At pharmacologic concentrations, ciprofloxacin hydrochloride, cefuroxime axetil, and nitrofurantoin monohydrate adversely affected motility with decreased rapid progression. Cessation of motility occurred in cefuroxime axetil and nitrofurantoin monohydrate. Sperm hyperactivation was also absent. Cefuroxime axetil decreased the percentage of intact acrosomes. In contrast, physiologic doses of ciprofloxacin hydrochloride or ofloxacin enhanced sperm fertilizing capacity.

CONCLUSION(S)

Ciprofloxacin affected hyperactivation by altering membrane properties, whereas doxycycline inhibited the capacitation process. Cessation of motility in cefuroxime axetil was linked to disrupted sperm head membranes. Sperm motility and fertilizing capacity were decreased in nitrofurantoin because of decreased metabolism. The positive effect of ofloxacin on fertilizing capacity did not involve changes in acrosome.

Polymerase chain reaction enzyme-linked immunosorbent assay detection of mycoplasma consensus gene in sperm with low oocyte penetration capacity

OBJECTIVE

To determine the prevalence of mycoplasmas in washed sperm and to compare the penetration of zona-free hamster oocytes by sperm with and without mycoplasmas.

DESIGN

Prospective comparative study.

SETTING

Clinical and academic research environment.

PATIENT(S)

Semen from 34 male patients.

INTERVENTION(S)

Specimens were divided, Percoll washed, and scanned for differences in kinematic parameters. Sperm DNA was extracted and assayed for mycoplasma DNA using the polymerase chain reaction-ELISA method targeting the consensus gene of 15 mycoplasma species. Remaining sperm were processed by centrifuge, Percoll, or TEST (TES and Tris) Yolk Buffer (TYB) and assessed for penetration capacity.

MAIN OUTCOME MEASURE(S)

Detection of mycoplasma DNA.

RESULT(S)

Mycoplasma DNA was detected in 29.4% of the Percoll-washed sperm. The penetration of oocytes by mycoplasma-positive sperm (59.5% +/- 17.3%; mean +/- SEM) was less than mycoplasma-negative sperm (86.8% +/- 5.4%) in the TYB-processed group.

CONCLUSION(S)

Mycoplasma DNA is demonstrated in almost a third of the Percoll-washed sperm. Because there were no other cell types except sperm, the results suggest that the mycoplasmas were either internalized or attached to the membranes. The reduced penetration by mycoplasma-positive sperm after 48-hour TYB suggest mycoplasmas required time to affect sperm function. Similarities between hypo-osmotic swelling and between kinematic parameters suggest that the mechanism does not involve differences in membrane integrity and in motility patterns.

Evaluation for antisperm antibodies after storage of sperm in TEST-yolk buffer

OBJECTIVE

To determine if TEST-yolk buffer, consisting of TES (N-tris [hydroxymethyl]-methyl-2-aminoethanesufonic acid), Tris (Tris[hydroxymethyl]aninomethane), and chicken egg yolk, affects the presence of antisperm antibodies on the sperm surface as detected by the immunobead test.

DESIGN

A prospective study of antisperm antibodies on sperm surface before and after incubation in TEST-yolk buffer. Direct immunobead test and indirect immunobead test were done the day of collection of the semen sample to detect the presence of human immunoglobulin class G (IgG) and immunoglobulin class A (IgA); immunobead tests were repeated on the same sperm samples after 24 hours of storage in TEST buffer.

SETTING

Academic tertiary institution.

PARTICIPANTS

Patients undergoing evaluation for infertility.

RESULTS

There was no significant difference in the outcome of the direct immunobead test after extending semen samples with TEST-yolk buffer for 24 hours at 4 degrees C. Eleven samples that were initially negative for IgG and 13 samples that were negative for IgA remained negative after 24-hour storage in TEST-yolk buffer. Eleven samples that were positive for IgG and nine samples that were positive for IgA by the direct immunobead test the first day remained positive the next day. Five extended sperm samples used in the indirect immunobead test with IgG positive serum gave positive results and four of five used with IgA positive serum gave positive results.

CONCLUSIONS

These findings suggest that TEST-yolk buffer can be used to extend semen without affecting the presence of antibodies on the sperm surface as indicated by the direct immunobead test. The higher variability of the indirect immunobead tests indicates there may be some alteration of sperm antigens after storing in TEST-yolk buffer. These findings indicate that TEST-yolk buffer can be used to store semen for batched processing of samples or as a transport medium for delivery to a central laboratory for antibody testing.

The effect of peritoneal fluid from patients with endometriosis on human sperm function in vitro

OBJECTIVE

Our purpose was to evaluate the effect of peritoneal fluid from women with endometriosis on sperm motility and function in an in vitro model.

STUDY DESIGN

Peritoneal fluid was collected at laparoscopy from patients with and without endometriosis. Human donor sperm was diluted with this fluid, and its effect on sperm function and motility was measured was measured with the zona-free hamster egg sperm penetration assay and computer-assisted semen analysis.

RESULTS

The mean number of eggs penetrated by the sperm mixed with peritoneal fluid from patients with endometriosis was significantly fewer than the number penetrated by the sperm mixed with fluid from control patients (22.9 +/- 5.31 vs 44.4 +/- 4.96, p < 0.01, Student t test, n = 20). When evaluated by computer-assisted semen analysis, sperm mixed with peritoneal fluid from patients with endometriosis showed a significant decrease in mean swimming velocity compared with sperm mixed with peritoneal fluid from control patients (54.0 +/- 1.77 vs 59.2 +/- 1.05, p = 0.02, Student t test, n = 20). A significant increase in the fraction of sperm swimming at slower velocities was also found. A trend toward a positive correlation between eggs penetrated and sperm velocity was seen, but statistical significance was not achieved (correlation coefficient 0.4392, p = 0.053, n = 20).

CONCLUSION

These data suggest that substances found in the peritoneal fluid of patients with endometriosis could contribute to infertility through impairment of both sperm function and motion kinematics.

Some cases of human male infertility are explained by abnormal in vitro human sperm activation

OBJECTIVE

To determine if a human sperm activation assay can be used to evaluate males exhibiting otherwise unexplained infertility.

DESIGN

Sperm from age-matched fertile and idiopathic infertile males were assayed in the human sperm activation assay and the results were compared. A portion of the sperm from the idiopathic infertile males also was used in assisted reproductive technology (ART) attempts at pregnancy.

PATIENTS

Idiopathic infertile couples who had extensive fertility testing with no identified problems that would explain their infertility. Fertile males that had fathered one or more children.

MAIN OUTCOME MEASURES

Sperm nuclear decondensation-recondensation and DNA synthesis. Pregnancies resulting from ART using semen from a male whose sperm responded abnormally in the human sperm activation assay.

RESULTS

Thirteen (22%) of 59 idiopathic infertile males produced sperm that responded abnormally in the human sperm activation assay. Only 1 (1.7%) of 59 fertile males produced sperm that responded abnormally in the human sperm activation assay. The percentage of abnormal responders in the patient group exhibiting unexplained infertility was significantly higher than in the fertile male group. No sperm samples that responded abnormally in the human sperm activation assay resulted in pregnancies when used in ART.

CONCLUSIONS

The human sperm activation assay is a new and independent indicator for some cases of infertility that otherwise would be unexplained. The human sperm activation assay appears to have utility in determining a sperm sample's efficacy for fertilization in ART attempts at pregnancy.

Analysis of TEST (TES and Tris) yolk buffer effects on human sperm

OBJECTIVE

To assess different parameters of TEST (TES and Tris) yolk buffer (TYB) treatment of human sperm that may contribute to the biologic effects of TYB on sperm function.

DESIGN

The influence of TYB treatment on occurrence of acrosome reactions was studied, as was the influence of the concentration of acrosome-reacted sperm reacted by TYB or Biggers-Whitten-Whittingham medium (BWW) incubation on penetration levels in the sperm penetration assay (SPA). The necessity for the TYB to achieve enhanced SPA performance as well as the effect of heat shock on sperm also were studied.

SETTING

Andrology laboratory of a university hospital.

PATIENTS

Sperm donors.

MAIN OUTCOME MEASURES

Sperm penetration levels in the SPA and acrosomal loss as evaluated by a fluorescent lectin staining technique.

RESULTS

Sperm incubated in TYB for 42 to 46 hours at 4 degrees C demonstrated a higher rate of acrosomal loss than did sperm capacitated in BWW media for 20 to 22 hours. The difference was not significant. When insemination concentrations were normalized to identical concentrations of acrosome-reacted sperm, TYB treated specimens demonstrated much higher penetration levels compared with BWW specimens. Samples incubated in BWW versus TYB for 42 to 46 hours at 4 degrees C before heat shock had identical penetration levels. Samples washed with 37 degrees C BWW (positive heat shock) had significantly higher penetration levels than did samples washed with 4 degrees C BWW (negative heat shock).

CONCLUSION

Although TYB treatment does increase the occurrence of acrosome reactions, this alone does not account for the dramatic increase in penetration levels in SPA seen with these samples. TEST yolk buffer is not required for enhancement of penetration, and the heat shock step of the procedure seems to be most important for enhancement of sperm fusion ability in the SPA.

Hypoosmotic swelling test for quality control of sperm prepared for assisted reproduction

This study evaluates the clinical usefulness of one additional parameter for assessment of human sperm cell function in vitro--the hypoosmotic swelling test. The hypoosmotic swelling test evaluated the functional integrity of the sperm plasma membrane. The investigation included a comparison of the hypoosmotic swelling test in samples containing motile and immotile spermatozoa and their correlation with the intrauterine insemination outcome. Motile spermatozoa expressed better membrane characteristics, without any importance of the hypoosmotic conditions. Positive correlation exists between HOS results and the outcome of IUI. This test can be a useful addition to the standard battery of semen analyzing tests.

Comparison of bovine sperm capacitation systems for ability of sperm to penetrate zona-free hamster oocytes and bovine oocytes matured in vitro

Sperm from the same ejaculate were capacitated in calcium-free Tyrode's, modified Tyrode's with bovine follicular fluid or heparin, and TEST-yolk. Capacitated sperm were coincubated with zona-free hamster oocytes at 37 degrees C for 3 h or with bovine cumulus-enclosed oocytes matured in vitro for 8 h at 37 or 39 degrees C. Bovine oocytes were transferred to fertilization medium and incubated for 72 h at 37 or 39 degrees C. Penetration of zona-free hamster oocytes was highest in calcium-free Tyrode's (53.7%), followed by Tyrode's with follicular fluid (50.6%), TEST-yolk (48.6%), and Tyrode's with heparin (34.2%). Penetration of bovine cumulus-enclosed oocytes matured in vitro at 37 degrees C was highest with heparin (48.1%), followed by TEST-yolk (35.0%), calcium-free Tyrode's (32.5%), and follicular fluid (26.4%). Sperm capacitation with heparin, assayed by penetration of bovine oocytes at 39 degrees C, was better at 39 degrees C (77.1%) than at 37 degrees C (46.1%). However, penetration rates in calcium-free Tyrode's and TEST-yolk were higher at 37 degrees C. The capacitation system with heparin at 39 degrees C and bovine oocytes was best followed by the systems using TEST-yolk and calcium-free Tyrode's at 37 degrees C.

Acrobeads test using monoclonal antibody-coated immunobeads: clinical application

Acrosome-reacted sperm was examined in infertile and fertile males using the Acrobeads test. The Acrobeads score was significantly higher in fertile males than in infertile males with normal or abnormal seminal findings (p < .005 and p < .001, respectively). The Acrobeads score was 2 or more in all the fertile males, but 62% of the infertile males with abnormal seminal findings (p < .02). Therefore, a disturbance in the acrosome reaction is suggested to be one of the causes of decreased fertility potential. A high correlation was found between Acrobeads score and sperm motility (r = .46, p < .001) or motile sperm concentration (r = .51, p < .0001). The Acrobeads test, the results of which reflect the acrosome condition of the sperm, is useful in the assessment of sperm function related to fertility.

Production of mouse monoclonal antibodies directed against the oolemma of human and hamster oocytes by intra-splenic injection of oocytes

PROBLEM

To develop an additional approach for the study of oolemmal surface moieties involved in gamete interactions, we decided to obtain monoclonal antibodies by intrasplenic injection of human and hamster oocytes in Balb/c mice.

METHOD

Two Balb/c males were injected three times intrasplenically at 15-day intervalS with approximately 40 zona-free hamster and 3-5 zona-free human oocytes. After the third injection, spleen cells were fused and hybridomas developed. We used a novel screening system based upon the use of sections of frozen human and hamster eggs, tested by means of indirect immunofluorescence. The antibodies that we produced were evaluated for their ability to interfere with the zona-free hamster eggs penetration by human spermatozoa. The B2B5 antibody was also developed as ascitic fluid and further characterized.

RESULTS

Seven antibodies reactive with hamster oocytes were produced. Six of them also reacted with human oolemmas. The binding was confined to the oolemma, and no staining of the zona nor the cytoplasm was present. One of these antibodies reduced the penetration of zona-free hamster eggs by human spermatozoa. This antibody, B2B5, an IgM kappa, was confirmed to interact with the oolemma by means of indirect immunofluorescence of fresh eggs and Covasphere binding. B2B5 did not react with other human or hamster tissues except capacitated human spermatozoa. The reactivity with the oolemma of hamster oocytes was not lost after egg penetration by human sperm.

CONCLUSIONS

Intrasplenic immunization using zona-free human and hamster oocytes allows the production of anti-oolemma antibodies. A system of screening based upon the use of sections of frozen eggs also allows an easy and quick scoring of many supernatants. B2B5 monoclonal anti-oolemma antibody deserves further studies in that is able to interfere with fertilization and its antigen appears to be confined to the gametes surface.

Advanced methods for evaluation of sperm quality

Routine semen analysis includes measurements of sperm concentration, motility, and morphology. In our study, three additional tests were evaluated in relation to fertilization rate in an in vitro fertilization program: the freezing and hypo-osmotic swelling tests that evaluate the functional integrity and stability of the sperm membrane under extreme osmotic conditions, and migration sedimentation test that isolates high-quality motile sperm cells. The study was performed on semen delivered by men of couples treated at the In Vitro Fertilization Unit, and men who served as semen donors (fresh or cryopreserved semen). No correlation was found between the sperm fertilization rate, and the decrease in motility percent following the freezing-thawing process. Thus, the freezing test cannot be used to predict semen fertilization capacity. The hypo-osmotic swelling test was applied on semen given by a similar population of men. While the hypo-osmotic swelling test values carried out with fresh semen was found to have good correlation with fertilization, no correlation was found when frozen thawed semen was used. Post-migration sedimentation test sperm characteristics, and especially the recovery rate of the motile sperm, were significantly better in in vitro fertilization cycles with fertilizations. Both the hypo-osmotic swelling test and migration sedimentation test can assist in evaluating semen quality, judged by the fertilization rate in an in vitro fertilization program.

Effect of low-dose prednisolone on sperm fertilizing capacity in subfertile men with circulating antisperm antibodies

To assess if low-dose prednisolone reduced circulating antisperm antibodies and improved sperm fertilizing capacity, the hamster oocyte penetration test (HOPT) was used to evaluate treatment in 36 males with significant serum antisperm antibodies, measured by the tray agglutination test (TAT). Prednisolone 5 mg three times a day for 3 months was used. Only couples in whom all tests in the female partner were normal were entered into the study. A significant increase in sperm density, normal morphology, and HOPT were noted after therapy (p < .001). A significant decrease in antisperm antibody titer was noted (p < .0001) and correlated with improvement of HOPT (p < .05). There were no significant side effects. Six pregnancies (17%) occurred. Three pregnancies (18%) occurred in partners of an untreated group of 17 men. Prednisolone therapy in this regime does not significantly improve pregnancy rates. The HOPT does not offer any additional information for predicting patients who will show an improvement in antibody titers or achieve pregnancy after steroids.

Effect of the intrauterine contraceptive device on protein components of human uterine fluid

The albumin, immunoglobulin G (IgG), immunoglobulin A (IgA), lysozyme, lactoferrin, alpha 1-antitrypsin, alpha 1x-antichymotrypsin, and neutral proteinase levels of uterine fluid and serum of IUD-bearing women were studied in relationship to the phase of the menstrual cycle, the length of IUD implantation and the presence of reported side effects. Selection of these proteins was based on their potential importance in IUD-induced contraceptive action and/or side effects. Generally, only small differences were found in the serum levels of these proteins during the cycle, with different length of implantation or between patients with and without side effects. However, transudation of proteins (albumin, IgG, alpha 1-antitrypsin, alpha 1x-antichymotrypsin) from blood into the uterine cavity was enhanced by the IUD, especially during the postmenstrual and premenstrual periods. The IUD enhanced the local secretory response even more, i.e., the increased release of proteins from the endometrium (lysozyme, neutral proteinase, IgA) and from leukocytes (lysozyme, lactoferrin). Protein changes occurred as the period of insertion increased. These changes in the uterine milieu may account in part for the contraceptive action of the IUD. The secretory proteins rather than the transudation products differed between patients who showed IUD-associated side effects vs. those who did not, implying that IUD-related pathology is primarily associated with changes in local secretory response. The possible role of each protein in the mechanism of IUD action is presented in view of the present findings.

Varicocelectomy: changes in Resazurin Reduction test

The Resazurin Reduction Test was performed on semen specimens from 27 patients with varicocele before and after varicocelectomy. The increases in both sperm concentration and motility were slight 3 months after surgery, but sperm concentration significantly improved 6 months after surgery (P < 0.01). The positive rate in the Resazurin Test significantly increased 3 and 6 months after surgery (each, P < 0.05) and the resazurin grade also increased at these times (each, P < 0.01). Of 13 patients with improved seminal findings, 7 had negative reactions during the preoperative Resazurin Test and 3 of these 7 patients continued to have negative reactions, while the other 4 had positive reaction after surgery. Of 14 patients with no improvement of semen characteristics, 6 continued to have negative reactions after surgery, but 4 with negative reactions before treatment showed positive reactions postoperatively. The Resazurin Test seems to assess fertility potential accurately after varicocelectomy.

Evaluation and treatment of infertility in spinal cord injured men through rectal probe electroejaculation

A total of 18 men older than 19 years with spinal cord injury was evaluated for fertility potential with testing of semen obtained by rectal probe electroejaculation. After fertility testing, including sperm penetration assay, semen cryopreservation and sperm antibody status, 6 of the 18 men proceeded with their partners to use rectal probe electroejaculation in efforts to conceive. Sperm was obtained in 16 of 18 cases. Average ejaculate total sperm count (306 million) was good but motility (22%) was poor. Adequate sperm retrieval after processing yielded a normal sperm penetration assay in 4 of 16 cases (25%) in which sperm were obtained. Favorable semen cryopreservation (greater than 33% of pre-freeze motility noted after thaw) was present in 5 of 16 cases (31%). Live births were achieved in 2 of 6 couples attempting conception. Despite the typically poor sperm motility noted in electroejaculates, rectal probe electroejaculation can result in pregnancies from couples involving spinal cord injured men. The sperm penetration assay data indicate that pregnancy should be achievable in at least 25% of spinal cord injured couples. Achieving these conceptions requires a team approach involving a urologist/andrologist, gynecologist/reproductive endocrinologist and a sperm-processing laboratory.

Zona-free sperm penetration assay and inducers of the acrosome reaction: a model for sperm microinjection under the zona pellucida

In order to minimize the percentage of false-negative results in the zona-free sperm penetration assay (SPA), a wide range of substances and/or physical agents capable of inducing the acrosome reaction (AR) have been incorporated in the incubation medium. These agents can also be used for treatment of severe male infertility using the technique of sperm microinjection under the zona pellucida (SMUZ). In the present review, the percentages of acrosome-reacted spermatozoa induced by several physiological, biochemical or physical agents published in the literature are compared in order to find the most efficient method(s) of inducing the AR in human sperm as a previous requirement of optimizing the technique of SMUZ. A working estimate of the level of efficiency of a given AR inducer is calculated by adding up its range score in each of three different arrangements from the highest to the lowest value of percentages of AR and differences in percentages of AR and penetration indexes between treated and control groups in SPA. The agents able to induce the AR by nonphysiological (electropermeabilization, lysophosphatidyl choline, and freezing-thawing) have better positions in this hierarchical system than those ones which require the active participation of sperm membrane receptors or second messenger systems (progesterone, zona pellucida, and stimulators of protein kinase A). Electropermeabilization appears to be the most efficient AR inducer. However, more possibilities need to be explored to enhance the relatively low percentages of acrosome-reacted spermatozoa shown by infertile men.

Swim-down: a rapid and easy method to select motile spermatozoa

A method is developed to improve the quality and the number of sperm recovered after laboratory processing, consisting of a swim-down technique. This study was designed to compare quality sperm after selection with a swim-up and a swim-down method. Fifty-nine men, 23-52 years of age, with a period of infertility of 1 to 14 years were included in the study. The efficacy of the swim-down technique as compared to the swim-up technique was assessed by measuring percentage of sperm recovery, sperm motility, the hypoosmotic swelling test, acrosome reaction, and the sperm penetration to zona-free hamster oocyte assay. The swim-down procedure using pure serum as culture medium showed a higher percentage (p < .02) of spermatozoa with forward progression and a higher number of recovered (p < .05) spermatozoa than the swim-up technique. The fertilizability was similar with both methods. The swim-down procedure using pure serum could be useful for intrauterine insemination where a higher number of spermatozoa is required.

Enhanced gamete interaction in the sperm penetration assay after coincubation with pentoxifylline and human follicular fluid

OBJECTIVE

To evaluate the effect of pentoxifylline and heat-inactivated human follicular fluid (FF) on performance in the sperm penetration assay (SPA) as a paradigm for the effect of these agents on human sperm-egg interaction in vivo and in vitro fertilization.

DESIGN

Semen specimens from men undergoing SPA testing for evaluation of suspected male factor infertility were coincubated with neat medium or media supplemented with pentoxifylline or human FF in a nonblinded manner.

PARTICIPANTS

Twenty male factor infertility patients.

INTERVENTIONS

Semen specimens were preincubated with: [1] pentoxifylline 0.25 mg/mL; [2] 10% human FF; [3] pentoxifylline+human FF; and [4] neat Biggers, Whitten, and Whittingham medium.

MAIN OUTCOME MEASURES

Differences in the rate of penetration of zona-free hamster oocytes.

RESULTS

Preincubation with either human FF or pentoxifylline produced a significant improvement in hamster egg penetration rates. Coincubation with a combination of human FF and pentoxifylline resulted in a significant enhancement of penetration as compared with single agent treatment.

CONCLUSIONS

Coincubation of sperm with human FF and pentoxifylline may provide a means of enhancing sperm activity for insemination and assisted reproduction.

Stability of the hypoosmotic swelling test over time

The results of the sperm count, motility, and hamster oocyte penetration (SPA) tests have been found to vary greatly in individuals who have had tests performed on more than one occasion. The study presented herein was designed to evaluate the stability of the hypoosmotic swelling (HOS) test over time. A total of 444 patients were classified into categories according to the time interval between HOS tests: 0-90 days (n = 267), 91-180 days (n = 35), 181-270 days (n = 37), 271-360 days (n = 30), 1-2 years (n = 54), and > 2 years (n = 21). A paired t test was used to compare mean HOS scores. The correlation between the HOS test of the first specimen and the HOS of the second specimen was calculated. For those who had 2 tests the only significant difference was found in the > 2 year group (69.67 +/- 9.13 vs. 64.23 +/- 12.83%), p < .05. When comparing the first and third HOS test in 74 patients, there was a significant (p < .05) decrease in the later test when the interval was greater than 270 days. The difference was not significant when the HOS results were classified as subnormal (< 50%) and normal (> or = 50%) for that same time period. It would appear that this test is reproducible, rarely fluctuates, but tends to become less dependable over longer intervals of time.

A freezing and thawing method of hamster oocytes designed for both the penetration test and chromosome assay of human spermatozoa

Superovulated hamster oocytes were cryopreserved and thawed according to our carefully designed procedures. More than 90% (92 +/- 4%) of oocytes survived freezing and thawing. They were proven to be well conserved, showing excellent performance comparable to freshly ovulated oocytes in the human sperm penetration test (proportion of penetrated ova: 94.7% vs. 93.6%) and human sperm chromosome analysis (proportion of metaphasic ova: 81.8% vs. 83.6%). There was no statistically significant difference in the incidences of sperm chromosome aberrations between assays using fresh and frozen-thawed oocytes. In addition, there was no statistically significant increase of aberrations in female pronuclear (hamster) chromosomes. This freezing-thawing method was found to be reliable, yielding viable hamster oocytes of high quality.

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.

Association of human sperm nuclear decondensation and in vitro penetration ability

Sperm nuclear decondensation is an integral step in fertilization which leads to the formation of the male pronucleus. The association between the in vitro spontaneous nuclear decondensation of human sperm and its fertilizing ability was studied in infertile male patients. The ability of sperm to fertilize an egg using the discontinuous two-layer Percoll method was significantly correlated to the percentage of decondensed swollen head (r = 0.43; P less than 0.005). The fertilizing ability of sperm processed with Test-Yolk buffer was correlated with the percentage of sperm at the fully decondensed stalk stage (r = 0.51; P less than 0.05). There were insignificant correlations for the whole-wash centrifugation, cryopreserved-thawed and swim-up methods. Samples of sperm that were positive (greater than 0% fertilization) in the sperm penetration assay had a higher percentage of decondensed sperm heads (66.7% vs. 20.6%) after Percoll wash or whole-wash centrifugation (60.5% vs. 44.3%) treatments compared with samples with no fertilization. Treatments that included Test-Yolk resulted in high percentages of decondensed swollen heads. The results suggest a positive association between sperm nuclear decondensation and the fertilizing ability of sperm, and affirm the importance of nuclear decondensation to the study of fertilization events.

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.

Sperm hyperactivation as quality control for sperm penetration assay

The sperm penetration assay (SPA) is subject to considerable variation, and controls are needed to verify the accuracy of the results. It is proposed that sperm hyperactivation (HA) can serve as a quality control check for the SPA. The objective was to determine if there was an association between the SPA outcome and sperm HA measured at various times during the SPA procedure. The data showed a significant correlation between percent sperm HA and percent zona-free oocyte penetration by sperm preincubated for three hours prior to sperm-oocyte interaction (short preincubation). Some sperm hyperactivity was observed in liquefied raw semen samples, but this was insignificantly related to SPA results. Low correlation was observed between SPA results and sperm HA determined immediately after centrifuge washing of sperm. The results suggest that it is possible to utilize sperm HA measured immediately after the sperm-oocyte interaction period as a quality control check of SPA results.

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.

Hypoosmotic swelling test in patients with varicocele

The hypoosmotic swelling test is a simple test for measuring the functional competence of human sperm membrane. Thirty-five patients with varicocele were assessed by hypoosmotic swelling test and the results were compared with those in patients with idiopathic infertility. Percentage of swollen sperm in varicocele tended to be lower than that in idiopathic infertility, especially in sperm concentration between 30 x 10(6)/mL and 40 x 10(6)/mL. Varicocele with sperm motility of 40% or more revealed lower percentage of swollen sperm than idiopathic infertility did. The results indicate that varicocele may particularly injure sperm membrane function because hypoosmotic swelling test is a test for measuring functional ability of human sperm membrane. The percentage of swollen sperm recovered after the operation earlier than did the other sperm parameters such as sperm concentration or motility, which indicates that impaired sperm membrane injury by varicocele is reversible.

Diadenosine tetraphosphate (Ap4A) and triphosphate (Ap3A) signaling of human sperm motility

The ubiquitous dinucleotide polyphosphate, diadenosine tetraphosphate (Ap4A), has been shown to be a signal molecule for DNA replication in mammalian cells. In this study, Ap4A and a related compound, diadenosine triphosphate (Ap3A), were tested for possible signaling functions in human spermatozoa. A computerized automated semen analyzer was used to detect changes in spermatozoa motility parameters. Cryopreserved-thawed donor spermatozoa were washed and incubated in 0.1 mM Ap4A, 0.1 mM Ap3A, or control medium. The data indicated that both Ap4A and Ap3A decreased the percentage of motile spermatozoa after 4 or more hours of incubation in vitro. The two dinucleotide polyphosphates caused an increase in the amplitude of lateral spermatozoa head displacement parameter only at the start of incubation. The other spermatozoa kinematic parameters were unaffected. No opposing ying-yang dual actions of Ap4A to Ap3A were seen. From the results, Ap4A and Ap3A were observed to be potential inhibitory signals of spermatozoa motility after prolonged exposure.

Relationship between hypoosmotic swelling test, semen analysis, and zona-free hamster ovum test

The hypoosmotic swelling test is a simple test for measuring the functional competence of the human sperm membrane. Fifty-four patients with idiopathic infertility were assessed by hypoosmotic swelling test and the results were compared with those of routine semen analysis and zona-free hamster ovum human sperm penetration test (ZSPT). Semen samples with abnormal semen parameters had lower percentage of swollen sperm in comparison with those with normal semen parameters. A positive correlation was observed between sperm concentration and sperm swelling (r = .50, p less than .05). A strong positive correlation was observed between the percentage of sperm motility and the percentage of swollen sperm (r = 0.60, p less than .01), and between motile sperm concentration and sperm swelling (r = .62, p less than .01). On the other hand, sperm swelling correlated only weakly with the percentage of sperm penetration. The results indicate that the hypoosmotic swelling test appears to evaluate different functional qualities of sperm than ZSPT.