Correlation between sperm morphology, acrosin, and fertilization in an IVF program

Does omitting teratospermia as a selection criterion for ICSI change pregnancy rates?

PURPOSE

There is controversy whether teratospermia is associated with poorer IVF outcomes and if ICSI may overcome this deficit. The debate likely lies in study heterogeneity, poor adjustment for confounders, and inter-observer variation in sperm morphology assessment. Given the current literature, a shift in practice was implemented at our center in February 2017, whereby teratospermia was no longer a criterion for ICSI. We hypothesized that, despite decreasing ICSI rates, we would see no change in ART outcomes.

METHODS

A retrospective study was performed including 1821 couples undergoing IVF/ICSI at a single center from January 2016 to December 2018, divided into cohorts before and after the practice change. The primary outcome of clinical pregnancy and secondary outcomes of fertilization, fertilization failure, good quality blastocyst formation, embryo utilization, positive hCG, and miscarriage rates was compared, adjusting for potential confounders. Subgroup analysis was performed evaluating teratospermia as the only reason for a male factor infertility diagnosis.

RESULTS

Despite a decrease in ICSI rate of 30.3%, we found no significant difference in clinical intrauterine pregnancy rate, with an adjusted relative risk of 0.93 (0.81, 1.07, P = 0.3008). There were no significant differences in other secondary outcomes after multivariate adjustment. Subgroup analysis for those with male factor infertility due to teratospermia showed no difference in outcomes.

CONCLUSION

This study concurs with the recent data suggesting that employing ICSI solely for teratospermia is unnecessary. This may allow clinics to decrease ICSI rates without sacrificing success rates, leading to lower cost and risk associated with treatment.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Predictors of pregnancy outcome for infertile couples attending IVF and ICSI programmes

The purpose of this study was to evaluate the predictors of pregnancy outcome for infertile couples attending in vitro fertilisation (IVF) and intracytoplasmic sperm injection (ICSI) programmes. Infertile couples attending IVF or ICSI procedures were included in this study. Related data including semen parameters and male and female age and body mass index were collected and analysed. The main outcome was clinical pregnancy, defined as an ultrasound detection of foetal heartbeat 6 weeks after embryo transfer. A total of 1316 couples who underwent IVF and 266 who underwent ICSI were recruited for this study. A multivariate logistic regression with likelihood ratio test revealed the following predictors of pregnancy outcome: female age and sperm DNA fragmentation index (DFI) and acrosomal activity in IVF procedures (chi-square of likelihood ratio = 26.42, d.f. = 3, P < 0.005) and female age and DFI in ICSI procedures (chi-square of likelihood ratio = 18.88, d.f. = 2, P < 0.005). In conclusion, our study indicated that sperm DFI, female age and acrosomal levels have a significant effect on ART pregnancy outcome.

Can intra cytoplasmatic morphologically selected sperm injection (IMSI) technique improve outcome in patients with repeated IVF-ICSI failure? a comparative study

OBJECTIVE

Spermatozoal morphology was reported to effect fertilization, embryo quality and pregnancy results in spontaneous conception and ART. Intracytoplasmic morphologically selected sperm injection (IMSI) is an innovative, not invasive technique, which examines the sperm with no harm at a magnification of 6000 × in order to obtain optimal sperm to perform IVF-ICSI. We evaluated the efficiency of IMSI technique in patients with repeated IVF-ICSI failure of at least three cycles with no viable pregnancy and/or very poor sperm quality.

STUDY DESIGN AND METHODS

All couples who performed IMSI between the years 2009 to 2012 were enrolled retrospectively to the study. Couples with male infertility who were treated with IMSI were included in the study. All their treatments were evaluated and divided into two subgroups: conventional IVF-ICSI treatment and their subsequent IMSI treatment. Demographic data, clinical parameters and outcome were recorded. The IMSI treatments were compared to previous non-IMSI treatments in terms of fertilization rates, cleavage rates, number of embryos and their quality, number of embryos transferred and pregnancy outcome.

MAIN RESULTS

Forty-two couples were reviewed. Basic characteristics of the groups were comparable. Fertilization and cleavage rates of the two groups were comparable. The embryos quality demonstrated a trend toward superior quality (grade 1-2) embryos in the IMSI versus ICSI (60% versus 47%; p = 0.07 and 53% versus 40%; p = 0.07), respectively. Implantation and clinical pregnancy rates were significantly superior in IMSI group (19.2% versus 7.8%; p = 0.042 and 41.3% versus 10.5%; p = 0.02, respectively). Miscarriage rate was significantly higher in conventional IVF-ICSI group (100% versus 15.8%; p = 0.04), and live birth rate was significantly higher in IMSI group (0 in conventional IVF-ICSI and 34.7% per transfer in IMSI group; p = 0.003).

CONCLUSION

IVF outcome of IMSI resulted in a higher implantation rate, pregnancy rate and most importantly delivery rate compare to non IMSI treated cycles.

[Complete fertilization failure following conventional IVF or ICSI: is it predictable? How to manage?]

The occurrence of complete fertilization failure following conventional in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI) is a rare event. Each of six physiological stages of the fertilisation can be failing. The cause of a fertilisation failure is either the spermatozoa, or the oocyte. The aim of this study was to determine if this event is predictable, and to define the later strategy. On all sperm tests available, it seems that only, tests of zona pellucida binding and acrosomique reaction are relatively predictive of a complete fertilization failure after IVF. No test allows at the moment to predict an oocyte contribution to unsuccessful fertilization. The strategy retained after a complete fertilization failure following the first attempt of IVF is to propose an ICSI; either to do an IVF if this event arises in the rank n+1, or when the number of inseminated oocytes was low. Concerning the ICSI, the low number of micro-injected oocyte is often in question; so the strategy retained following a first fertilization failure after ICSI is to perform a new ICSI attempt after optimization of the ovarian stimulation. When the cause is spermatic, it is indicated trying a modified ICSI with the use of pentoxifiline, or an intracytoplasmic morphologically selected sperm injection (IMSI), sometimes with assisted oocyte activation. In last solution, we can propose the ovum donation.

In vitro effects of α-tocopherol on teratozoospermic semen samples

A strong positive correlation exists between teratozoospermia and reactive oxygen species production, which in turn has negative effects on their in vitro fertilisation outcome. Our aim of this study was to determine potential protective effects of α-tocopherol on teratozoospermia motility, viability, acrosome reaction and DNA integrity after 1-h in vitro incubation. Teratozoospermic semen samples were obtained from 15 volunteers aged between 20 and 30 years after 3-5 days of sexual abstinence. Samples were washed, centrifuged and incubated in 37 °C and 5% CO(2) until sperm swimmed-up. Spermatozoa were counted in the supernatant and divided into four groups, each contained 2 × 10(6) sperm/ml(-1). Groups one to four were incubated for 1 h with Ham's F-10 solution as control group, 10 μm A23187, 40 μmα-tocopherol and 10 μm A23187 + 40 μmα-tocopherol respectively. The results indicated that α-tocopherol has ability to enhance teratozoospermia viability and motility, while there were no ameliorative effects on acrosome reaction and DNA fragmentation. A23187 induced acrosome reaction in teratozoospermia and α-tocopherol significantly diminished this effect. In conclusion, although α-tocopherol could improve teratozoospermia motility and viability, its effects on DNA integrity and acrosome reaction ability as supplementation IVF culture media are not obvious.

Discrepancy between sperm acrosin activity and sperm morphology: significance for fertilization in vitro

BACKGROUND

In routine semen analysis, discrepancies may occur between sperm acrosin activity test results and sperm acrosomal morphology.

METHODS

Discrepant test results of sperm acrosin activity (spectrophotometric assay) vs. sperm morphology (strict criteria) in the initial diagnostic investigation of 107 infertile couples were evaluated with respect to fertilization rate (% oocytes with 2 pronuclei) further obtained in IVF treatment.

RESULTS

Acrosin activity positively correlated with sperm morphology (% normal forms) (r=0.537) and fertilization rate (r=0.526). ROC curves for the prediction of > or =50% fertilization rate were comparable for acrosin activity and sperm morphology, with optimal cutoff values at 25 microIU/10(6) sperm and 10%, respectively. In multiple regression analysis, sperm acrosin activity (P=0.002) predicted fertilization rate independently of sperm morphology (P<0.001) and sperm vitality (eosin-nigrosin stain) (P=0.03). Acrosin activities > or =25 microIU/10(6) sperm were observed in 36% of severe teratozoospermic samples (< or =4% normal spermatozoa) associated with low fertilization rate. Twenty percent of the morphologically normal ejaculates showed a low acrosin activity (<25 microIU/10(6) sperm) and low hypoosmotic swelling test (HOST) scores (31.4+/-7.6%) and were associated with low fertilization rate.

CONCLUSION

The sperm acrosin assay can help to predict sperm fertilizing capacity in IVF independently of sperm morphology.

Assessment of sperm functional competence and sperm-egg interaction

A precise understanding in the functional competence of mammalian sperm is essential to generate clinical advances for the treatment of infertility and novel contraceptive strategies. The fundamental knowledge on the controlling parameters for spermatozoal activation process will help in the identifying the causes in fertilization failure due to male factor as well as in developing male contraceptive methodologies. The defects in the sperm-egg interaction seem to be one of the controlling mechanisms, however, none of the presently available methods for the evaluation of the fertilizing ability of sperm precisely indicates the reason for the failure or the success of sperm entry into egg. Adequate number of motile spermatozoa with normal morphology and timely occurrence of acrosome reaction are presumably the major prerequisites for the penetration through the egg investments. The present communication briefly reviews some of the main features of mammalian sperm which control the success or the failure of fertilization and existing clinical methods indicating the lack of fundamental knowledge on the sub-cellular and molecular aspects of this unique and species-specific cell-cell interaction.

Prognosis for sperm fertilizability: analysis of different variables in men

An overview of various sperm tests is presented. The standard semen analysis obtained by most clinicians evaluating infertility usually consists of sperm concentration, percent motility, quality of motility, and sperm morphology. Unfortunately, unless the motile density is extremely low, the count and motility are not good prognosticators of fertility potential. Values above the norm for normal fertile couples unfortunately cannot reliably predict normal fertility potential. It is important to find sperm tests that are easy to perform, are relatively inexpensive, and provide an accurate prognosis. Strict morphology was hoped to be such a tool with initial optimism that it was far superior to standard morphology. Unfortunately, this test also failed to be the ideal inexpensive prognostic test after further evaluation. One test that is inexpensive and highly correlates with fertilizability is the presence of antisperm antibodies since their presence frequently does not alter count, motility, or morphology. This test should be performed as part of the routine semen analysis. Other tests highly correlate with the achievement of pregnancy and are simple and inexpensive to perform, but, interestingly, do not correlate with fertilizability. These include the hypoosmotic swelling test (HOST) and the sperm stress test. Abnormalities in these tests imply a different abnormality of sperm that leads to conception failure and that is the transfer of a toxic factor from the sperm to oocyte to embryo that prevents the embryo from implanting. Certainly, the simple, inexpensive HOST should be performed routinely. Other tests of sperm function, e.g., sperm penetration assay, sperm zona pellucida binding assay, and acrosome reaction, have their definite place in the evaluation of the infertile male. However, because they are expensive and difficulty to perform they lend themselves to certain specific circumstances but not to routine testing.

Effect of progesterone on acrosome reaction, hypoosmotic swelling test, and DNA stability in human spermatozoa

The association between different sperm parameters, an in vitro effect of progesterone, has not been studied satisfactorily. In this article, the effect of progesterone on acrosome reaction (AR), plasma membrane integrity, and chromatin stability has been assessed in human spermatozoa with normal morphology and motility. Semen samples were obtained by masturbation from 25 patients. Two criteria of classification were utilized in this study: high motility group and normal morphology group incubated with progesterone. The effect of progesterone on AR, plasma membrane integrity, and chromatin stability in human spermatozoa with normal morphology and motility was realized. The results suggest that only the subpopulation of spermatozoa with normal morphology is able to undergo the progesterone-induced AR. It is possible that in the reproductive female tract it takes place a high selection of sperm with chromatin stability determined and optimal plasma membrane to undergo the AR prerequisite for the fecundation.

Chromatin cytophotometric analysis of abnormal bovine spermatozoa

Sperm head morphology is basically conditioned by the nuclear structure. The aim of the present work was to study the relation between nuclear morphological features, DNA content and chromatin distribution in morphologically normal vs. abnormal bovine spermatozoa. To this end, individual Feulgen-reacted spermatozoa were cytophotometrically studied. Chromatin compactation was evaluated by means of nuclear area, as well as mean and maximal absorbance of each nucleus. Morphological abnormality analysed included large, small, pear, narrow and round shapes, together with presumably 'diploid' sperms. Both large and small spermatozoa have a DNA content that does not differ significantly from normal values, but their area and mean and maximal absorbance are significantly different. Size variation seems basically due to altered chromatin compactation. The pear shapes have a narrower neck and a significant increase in maximal absorbance alone, which is invariably recorded in the neck zone whose increase would indicate a change in distribution and/or compactation. The narrow and round shapes fail to present significant variations in studied parameters. The possible 'diploids' differ significantly from normal cells in all studied variables, with a little area increase.

Acrosin activity in pelleted frozen sperm does not correlate with in vitro fertilization of oocytes

Spermatozoa pelleted after swim-up were frozen and then analysed in batches for acrosin activity, using a spectrophotometric method, and expressed as microIU micrograms DNA-1. A total of 259 sperm samples were analysed and the acrosin activity compared with fertilization in vitro. Of these, 224 samples fertilized at least one oocyte and 35 samples failed to fertilize any oocyte. Analysis by Student's t-test indicated that there was a statistically significant difference (P = 0.02) in acrosin activity between the two groups. However, when samples that failed to fertilize were matched for concentration, motility and normal morphology with samples that fertilized, this significance was lost (P = 0.77). It is concluded that total acrosin in pelleted sperm frozen after regular swim-up, does not correlate with fertilizing ability of spermatozoa used for insemination.

Prognostic value of the strict criteria: an Argentinian experience

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

The impact of woman's age and sperm parameters on fertilization rates in IVF cycles

OBJECTIVE

To examine the predictive value of different sperm parameters and the age of a couple on fertilization rate.

MATERIAL AND METHODS

One-hundred six consecutive sperm samples were analysed before insemination of oocytes in IVF cycles. Sperm count and motility were examined with the Makler Counter Chamber. Morphology was evaluated by the eosin nigrosin and giemsa stains. Membrane integrity was evaluated by the hypoosmotic swelling test (HOST).

RESULTS

Using a step-wise logistic regression test the following parameters were all significantly correlated with the fertilization rates: sperm concentration after a 3-h layering (chi 2 = 15.85, P < 0.001), sperm motility index (chi 2 = 6.12, P < 0.0134), woman's age (chi 2 = 6.25, P < 0.012), and the hypoosmotic test (chi 2 = 6.63, P < 0.01). A fertilization capacity formula was established by using these four parameters to predict the fertilization capacity of a couple. Significantly lower fertilization rates were detected in elderly women with the partner sperm concentration of 7 x 10(6)/ml after 3-h layering, < 30% swollen spermatozoa in the HOST and motility index score of < 50.

CONCLUSIONS

By the aforementioned formula, sperm fertilization capacity can be predicted by using simple sperm parameters and women's age. Elderly women with partners who have suboptimal sperm parameters reflected by low fertilization capacity scores may benefit from micro-manipulation procedures.

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

OBJECTIVE

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

DESIGN

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

SETTING

University-based tertiary care center.

PATIENTS

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

MAIN OUTCOME MEASURE

In vitro fertilization rates of inseminated ova.

RESULTS

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

CONCLUSIONS

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

Relation of human sperm acrosin activity and fertilization in vitro

The aim of the study described here was to determine the possible contribution of the acrosin activity test to routine semen analysis in enhancing the precision of the prognosis of IVF success in a group of patients in which the contribution of the egg factor to infertility was ruled out (20 cases) compared to a control IVF group (39 cases). Semen analysis, acrosin activity and acrosome ultrastructure were determined for all semen samples. The group with high fertilization rates was comprised of normozoospermic patients while the group with low fertilization rates was comprised of astheno-teratozoospermic patients. The mean acrosin level of the positive IVF group was significantly higher than that of the negative group (51.7 +/- 33.2 and 28.6 +/- 13.7, respectively). Two parameters: per cent motile spermatozoa and acrosin level, were found to have a significant positive correlation with subsequent successful IVF (r = 0.36, P < 0.006; r = 0.37, P < 0.004, respectively); and agenesis of the acrosome was found to have a significant negative correlation (r = -0.33, P < 0.01). The ability of these parameters to correctly predict fertilization success was 59%, with 5% false positive, among which 15.4% was predicted solely by the acrosin level (above 54 microIU 10(6) cells-1) and 23% solely by per cent motile spermatozoa (above 50%). Abnormalities of the acrosome ultrastructure did not contribute further to the correct classification. The apparent clinical benefit of the acrosin level test is discussed.

Acrosin activity of human sperm did not correlate with IVF

To evaluate the predicting value of sperm acrosin activity in human, the acrosin activity index (AAI) was measured in 95 semen samples from patients participating in an IVF program. All patients had at least two mature oocytes. Of 95 patients, 84 had successful fertilization and 11 failed to fertilize all oocytes in vitro. The numbers of mature oocytes were similar between fertilization and nonfertilization groups. The mean AAI, measured using a commercially available (Accu-Sperm) acrosin activity assay, was greater in the fertilization group than in the nonfertilization group, but the difference was not significant. There was no correlation between AAI and the in vitro fertilization rate of mature oocytes. The relation between AAI and semen parameters also showed no significant difference. It would appear that measurement of AAI inaccurately reflects in vitro fertilizability of human sperm.

Subzonal sperm insemination and total or extreme asthenozoospermia: an effective technique for an uncommon cause of male infertility

OBJECTIVE

To assess the value of subzonal insemination (SUZI) in cases of total or extreme asthenozoospermia.

DESIGN

The results of IVF after SUZI were assessed in six cycles (four couples) with documented asthenozoospermia.

SETTING

Institut de Médecine de la Reproduction, Marseille, France.

PATIENTS

Four couples underwent six retrieval cycles. In all cases asthenozoospermia was total (100% of immotile spermatozoa) or extreme (5% nonprogressive motility). Oligozoospermia and teratozoospermia were ruled out in all cases. In two cases electron microscopy revealed the absence of the central singlet in the flagellum axonemal complex and in one case a major dysplasia of the fibrous sheath in the flagellum principal piece.

RESULTS

The overall fertilization rate was 45%. The diploid embryo rate was 33%. Embryo quality was satisfactory. In five of six cycles, three embryos were transferred. Two triplet pregnancies were obtained corresponding to an implantation rate per transferred embryo of 40%.

CONCLUSION

Total or extreme asthenozoospermia seems to be a good indication for SUZI.

Correlation between male fertility and acrosin-like protease activity in rats treated with Spartium junceum

Intraperitoneal injections of extracts of Spartium junceum in adult male rats were shown to reduce the rate of fertility and acrosin enzyme activity. For the latter the drug effects could be divided into two phases: in the first stage a significant increase in proteolytic activity was observed in all experimental animals examined; and in the second stage, there was a general decrease of up to 50% in enzyme hydrolytic properties. There is a notable difficulty in correlating the acrosin activity and the data obtained from mating tests. The effect of drugs on the activity of another acrosomal protease, benzamidine-resistant protease, was assayed. A significant decrease in this enzyme was noted though the modality was different from that of acrosin. Extrapolating the data of the two co-extracted acrosomal proteases, the ratio of acrosin-like protease [E] and benzamidine-resistant protease [E]x, it was possible to correlate the value expressed to the rate of pregnancy. The implications of this finding is discussed although the exact molecular basis of the phenomenon is uncertain.

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.

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.

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.