Asthenozoospermic Subjects Research Articles

4BNT162b2 mRNA COVID-19 vaccine and semen: What do we know?

ABSTRACTBackgroundThe effects of an mRNA COVID‐19 vaccine on spermatozoa parameters are not known. The aim of this study was to evaluate the effect of the BNT162b2 mRNA COVID‐19 vaccine on human semen, comparing spermatozoa parameters before and after vaccine inoculation.Materials and methodsIn this single‐center prospective study, voluntary subjects who received mRNA vaccines from February to July 2021 were enrolled. The study population included male subjects aged between 18 and 45 years who completed the BNT162b2 mRNA COVID‐19 vaccine cycle. All subjects were evaluated before the first dose of vaccine (T0) and after 3 months (T1) with semen analysis and further analysis of seminal plasma, including colorimetric determination of reactive oxygen metabolites (d‐ROM test), electrolytes, and interleukin 6 (IL‐6) assessment by enzyme‐linked immunosorbent assay technology.ResultsThe experimental sample included 47 subjects (age: 29.3 ± 6.0 years, range 24–32; body mass index: 23.15 ± 2.5 kg/m2, range 19.2–28.0). All the subjects reported no systemic side effects. No significant differences were observed in any spermatozoa parameter between T0 and T1. A subanalysis was performed in oligoazoospermic and asthenozoospermic subjects, confirming the same results. Electrolyte analysis also showed no significant differences before and after vaccine inoculation. Finally, no significant differences were observed in T0, compared to T1 for the d‐ROM test and IL‐6.Discussion and conclusionIn this study, no significant differences in spermatozoa parameters before and after vaccine inoculations were found. Furthermore, oxidative stress analysis,, the activity of the cell membrane, and IL‐6, as a marker of inflammation, was not affected by the mRNA COVID‐19 vaccine. These results suggest that this vaccine is safe for male semen quality.

Oral Zinc Supplementation Restores Superoxide Radical Scavengers to Normal Levels in Spermatozoa of Iraqi Asthenospermic Patients

Oxidative stress and decreased antioxidant levels have been projected as potential factors involved in the pathophysiology of diverse male infertility types, including asthenospermia. The present study was conducted to examine the effect of zinc supplementation on the quantitative and qualitative characteristics of semen along with oxido-sensitive index level (superoxide dismutase/xanthine oxidase ratio) in the seminal plasma of asthenospermic patients. Semen samples were obtained from 60 fertile (age 31.6 ± 3.3 years) and 60 asthenospermic men (age 32.5 ± 3.23 years) from July 2011 to July 2012, from couples who had consulted the infertility clinic of the Babil hospital of maternity (Hillah, Iraq). The subfertile group was treated with zinc sulfate, every participant took 2 capsules (220 mg each) of zinc sulfate per day for 3 months. Semen samples were obtained (before and after zinc sulfate supplementation). Oxido-sensitive index level, catalase-like activity and various sperm parameters were measured. The value of the oxido-sensitive index of fertile controls (1.28 + 0.31 in seminal plasma and 1.57 + 0.62 in spermatozoa) was significantly higher than that of the infertile patient group (0.56 + 0.48 in seminal plasma and 0.65 + 0.57 spermatozoa) (p = 0.0001). Oxido-sensitive index levels were significantly higher in the infertile group treated with zinc sulfate (1.13 + 0.22 in seminal plasma and 1.15 + 0.16 in spermatozoa) (p = 0.001). Catalase-like activity was increased significantly in spermatozoa and seminal plasma of patients compared to that of healthy controls. Volume of semen, progressive sperm motility and total normal sperm count were increased after zinc supplementation. Zinc supplementation restores oxido-sensitive index and catalase-like activity in semen of asthenozoospermic subjects to normal ranges.

Protective effects of coenzyme Q10 and aspartic acid on oxidative stress and DNA damage in subjects affected by idiopathic asthenozoospermia.

Male infertility is negatively influenced by reactive oxygen species and by other oxidant radicals [1]. In this regard, the relevant role of Coenzyme Q10 (CoQ10) in contributing to the total antioxidant buffer capacity of semen has been extensively investigated [1]. Two distinct studies conducted by our group, showed that in idiopathic asthenozoospermic patients undergoing CoQ10 therapy a significant increase in spermatozoa motility was observed [1, 2], suggesting its potential therapeutic role. On the other hand, Aspartic acid (D-Asp) supplementation was found to increase the concentration and motility of spermatozoa in oligo-asthenozoospermic and asthenozoospermic subjects [3]. Some evidence suggests a protective effect against oxidative stress for this molecule [4]. Only a few interventional studies have assessed oxidative stress in sperm of idiopathic infertile men treated with CoQ10 and D-Asp [5–9]. However, they just examined some of the markers of oxidative stress, focusing, in the great majority of cases, only on subjects who were administered CoQ10 [6–9]. Given these premises, we conducted a study in infertile idiopathic subjects who underwent co-administration of CoQ10 and D-Asp in order to evaluate some previously untested parameters of sperm oxidative stress, like superoxide dismutase (SOD) activity, nitric oxide (NO) and peroxynitrite levels, and analyze the effects of these substances on sperm DNA damage markers.

Significant association of TNFα and IL-6 gene with male infertility—An explorative study in Indian populations of Uttar Pradesh

In this study were aimed to identify the association of SNPs candidate genes of TNF-α and IL-6 with hormones levels and sperm cells death in infertile subjects of Uttar Pradesh population in North India. The study population comprised, fertile donor (control group) and infertile group patients i.e. normozoospermic (idiopathic unexplained), oligozoospermic and asthenozoospermic groups, with 260 subjects in each group. Subjects were selected from the Departments of Urology, K.G's Medical University and Urology, SGPGIMS, Lucknow, India. The allele-specific polymerase chain reaction (PCR) and PCR-RFLP were used to investigate the substitution of the guanine (G)-to-adenosine (A) at position-308 and guanine (G)-to-cytosine (C) at position-174 in the promoter regions of the TNF-α and IL-6 genes, respectively. Further their relation to male fertility and sperm function were also investigated. It was found that the substitution levels from G to A and from G to C in the TNF-α and IL-6 genes, respectively, were significantly higher in the infertile subjects as compared to that of control group. The apoptosis and necrosis levels were also higher in oligozoospermic and asthenozoospermic infertile subjects. Further it was found to be associated with increased level of reactive oxygen species as observed in oligozoospermic and asthenozoospermic subjects. However, a significant decrease in testosterone and luteinizing hormone with increased prolactin and follicle stimulating hormones was observed in infertile subjects. The study populations indicating a strong association between TNF-α G-308A and IL-6 G-174C substitution with infertile men which is further supported by allele and genotype meta-analysis and thus established it as a risk factor.

Oral zinc supplementation restore high molecular weight seminal zinc binding protein to normal value in Iraqi infertile men

BackgroundZinc in human seminal plasma is divided into three types of ligands which are high (HMW), intermediate (IMW), and low molecular weight ligands (LMW). The present study was aimed to study the effect of Zn supplementation on the quantitative and qualitative characteristics of semen along with Zinc Binding Protein levels in the seminal plasma in asthenozoospermic patients.MethodsSemen samples were obtained from 37 fertile and 37 asthenozoospermic infertile men with matched age. The subfertile group was treated with zinc sulfate, every participant took two capsules per day for three months (each one 220mg). Semen samples were obtained (before and after zinc sulfate supplementation). After liquefaction seminal fluid at room temperature, routine semen analyses were performed. For determination of the amount of zinc binding proteins, the gel filtration of seminal plasma on Sephadex G-75 was performed. All the fractions were investigated for protein and for zinc concentration by atomic absorption spectrophotometry. Evaluation of chromatograms was made directly from the zinc concentration in each fraction.ResultsA significant high molecular weight zinc binding ligands percentage (HMW-Zn %) was observed in seminal plasma of fertile males compared with subfertile males. However, seminal low molecular weight ligands (LMW-Zn) have opposite behavior. The mean value of semen volume, progressive sperm motility percentage and total normal sperm count were increased after zinc sulfate supplementation.ConclusionsZinc supplementation restores HMW-Zn% in seminal plasma of asthenozoospermic subjects to normal value. Zinc supplementation elevates LMW-Zn% in seminal plasma of asthenozoospermic subjects to more than normal value.Trial registrationClinicalTrials.gov identifier NCT01612403

Altered Expression of Succinic Dehydrogenase in Asthenozoospermia Infertile Male

There is a possibility that mitochondrial respiration defects may contribute to asthenozoospermia. Immunocytochemical detection was used to localize succinic dehydrogenase (SDH) in the head and mid-piece of spermatozoa by fluorescent microscope. The study revealed dispersed SDH activity in the semen of asthenozoospermic subjects in comparison with control semen samples. While the stain intensity varied from cell to cell in controls as well as in patients, it was predominantly localized within mid-piece of spermatozoa in healthy individuals. In contrast, in semen of infertile male, the diffused and dispersed SDH immunoreactivity was observed in head as well as in mid-piece region of spermatozoa. Dispersed expression of mitochondrial SDH in head and mid-piece of spermatozoa of asthenozoospermia subjects indicates mitochondrial damage because of metabolic or genetic factors, affecting energy production and leading to disturbed sperm motility, which could be pathologically significant. Detailed mitochondrial SDH immunolocalization studies are warranted to establish a role of deranged tricarboxylic acid cycle in causation of male infertility.

Study into the Iron Content of Seminal Plasma in Normal and Infertile Subjects

The iron content in seminal plasma of normal (n19), oligozoospermic (n11), azoospermic (n12), oligoasthenozoospermic (n19), and asthenozoospermic (n17) subjects was estimated by using atomic absorption spectrophotometer. The concentration of iron in normal seminal plasma varied from 265 to 365 mg%. The source of iron in seminal plasma seems to be the adnexal glands and not spermatozoa, as azoospermic semen also contained it. A statistically highly significant difference was seen when normal was compared with azoospermia and with asthenozoospermia. The necessary average wastage of iron through semen is calculated as 2.52 mg/day. This value is highly variable according to the seminal volume and frequency of ejaculation.

The role of mitochondria in energy production for human sperm motility

Mitochondria of spermatozoa are different from the corresponding organelles of somatic cells, in both their morphology and biochemistry. The biochemical differences are essentially related to the existence of specific enzyme isoforms, which are characterized by peculiar kinetic and regulatory properties. As mitochondrial energy metabolism is a key factor supporting several sperm functions, these organelles host critical metabolic pathways during germ cell development and fertilization. Furthermore, spermatozoa can use different substrates, and therefore activate different metabolic pathways, depending on the available substrates and the physico-chemical conditions in which they operate. This versatility is critical to ensure fertilization success. However, the most valuable aspect of mitochondria function in all types of cells is the production of chemical energy in the form of ATP which can be used, in the case of spermatozoa, for sustaining sperm motility. The latter, on the other hand, represents one of the major determinants of male fertility. Accordingly, the presence of structural and functional alterations in mitochondria from asthenozoospermic subjects confirms the important role played by these organelles in energy maintenance of sperm motility. The present study gives an overview of the current knowledge on the energy-producing metabolic pathways operating inside human sperm mitochondria and critically analyse the differences with respect to somatic mitochondria. Such a comparison has also been carried out between the functional characteristics of human sperm mitochondria and those of other mammalian species. A deeper understanding of mitochondrial energy metabolism could open up new avenues of investigation in bioenergetics of human sperm mitochondria, both in physiological and pathological conditions.

Absence of annulus in human asthenozoospermia: Case Report†

The annulus is a septin-based ring structure located at the junction of the midpiece (MP) and the principal piece (PP) of spermatozoa flagellum. In the mouse, deletion of Septin 4, a structural component of the sperm annulus, prevents annulus formation and leads to MP-PP disjunction, flagellar bending, asthenozoospermia and male sterility. Testis anion transporter 1 (Tat1) is a germ cell-specific member of the SLC26 anion transporter family and is co-expressed with Septin 4 at the sperm annulus. Interestingly, Tat1 null sperm bear an atrophic annulus, causing a phenotype similar to that of Sept4 null sperm. We searched for Tat1 misexpression and/or mislocalization in spermatozoa from asthenozoospermic subjects (n = 75) and controls by performing an immunofluorescence detection assay on sperm smear preparations. We found one patient showing moderate asthenozoospermia, with 97% of sperm lacking Tat1, Septin 4 and Septin 7 proteins at the annulus. We confirmed the absence of the annulus structure by transmission electron microscopy and observed that spermatozoa from the patient displayed MP-PP disjunction and abnormal mitochondrial organization. We show that the structural defects in sperm are not caused by abnormal transcription or point mutations of the TAT1 and SEPT4 genes; however, although both proteins are expressed, they are not properly localized at sperm annulus. The case we studied, so far unreported in human, confirms the involvement of Tat1 and Septin proteins in the constitution of the annulus, but also raises questions about the function of this structure in human sperm motility.

Relationship between seminal antioxidant enzymes and the phospholipid and fatty acid composition of spermatozoa

Sperm cell membranes are susceptible to peroxidative damage through an excess of reactive oxygen species. The objective of this study was to determine seminal plasma glutathione peroxidase (GPX) and superoxide dismutase (SOD) activity and relate these to phospholipid profiles and phospholipid-esterified fatty acid composition of spermatozoa. Seminal plasma GPX and SOD activity, phospholipid, phospholipid-esterified fatty acid composition and malondialdehyde (MDA) of spermatozoa were assayed in 10 normozoospermic and 25 asthenozoospermic subjects. Mean seminal GPX and SOD activity in normozoospermic men were not significantly different from asthenozoospermic men. A significant positive correlation was observed between seminal plasma GPX activity and phosphatidylcholine content ( r = +0.77, P = 0.037) and there was a significant negative correlation with lysophosphatidylcholine content ( r = −0.89, P = 0.02) in normozoospermic sperm samples. Positive correlations were found between SOD activity and polyunsaturated fatty acid composition of spermatozoa. MDA content in the spermatozoa of asthenozoospermic subjects was significantly higher than in normozoospermic males ( P < 0.05). Negative correlations were found between MDA content and seminal SOD activity and arachidonic acid content of spermatozoa from normozoospermic samples ( r = −0.5; P = 0.046, r = −0.9; P = 0.001 respectively). Seminal plasma GPX and SOD provide protection against lipid peroxidation of phospholipid and phospholipid-bound fatty acids in normozoospermic samples.

Oxygen uptake by mitochondria in demembranated human spermatozoa: a reliable tool for the evaluation of sperm respiratory efficiency

In this work we report a relatively simple and fast method for analysing oxygen consumption and therefore mitochondrial functionality, in individual human ejaculates. This oxygraphic method requires a low number of cells, is highly reproducible and linearly correlates with sperm concentration. Our results have shown that oxygen uptake by mitochondria of demembranated sperm cells from normozoospermic subjects is significantly stimulated by a large set of respiratory substrates and ADP. The respiratory control ratio (RCR) values indicate a good coupling between respiration and phosphorylation by sperm mitochondria and thus a well preserved integrity of the mitochondria themselves. Interestingly, whereas the rates of oxygen uptake, as expected, changed with different sperm concentrations, the RCR values remained constant, thus demonstrating a linear response of the assay. In asthenozoospermic subjects, however, a significant decrease in the sperm respiratory efficiency was found. The results obtained suggest that this method, besides its potential clinical application, could be useful for a deeper understanding of the biochemical properties of sperm mitochondria and their role in ATP production in human spermatozoa.

Seminal plasma levels of 15-F2α-isoprostane, malondialdehyde and total homocysteine in normozoospermic and asthenozoospermic males

It has been proposed that oxidative stress plays an important role in male infertility. The aims of this study were to compare seminal plasma levels of 15-F2t-isoprostane (8-iso-PGF2α), malondialdehyde (MDA), and total (sum of free and bound) homocysteine (tHcy) from normozoospermic vs. asthenozoospermic men, and to examine the relationships between tHcy and lipid peroxidation products. The study was a case-control study with a simple random sampling. The case group was consisted of 15 asthenozoospermic males. This group was compared with 15 normozoospermic men. Seminal plasma levels of 15-F2α-isoprostane and tHcy were measured using commercially available enzyme immunoassay (EIA) kits. MDA levels were determined by the thiobarbituric acid (TBA) assay. The Mann-Whitney U test was used to compare two groups. Coefficients of correlation were calculated using Spearman's correlation analysis. All hypothesis tests were two-tailed with statistical significance assessed at the p value <0.05 level. MDA levels were higher in asthenozoospermic subjects than in control subjects (0.72±0.06 μM vs. 0.40±0.06 μM; p<0.05). No differences were seen in 15-F2α-isoprostane levels in asthenozoospermic subjects and controls (65.00±3.20 pg/ml vs. 58.17±4.12 pg/ml; p>0.05). Interestingly, tHcy levels were to be slightly higher in asthenozoospermic subjects than in controls (6.18±1.17 μM vs. 4.8±0.52 μM). Sperm motility was inversely correlated with seminal plasma 15-F2α-isoprostane and MDA levels, respectively (p<0.05). In summary, seminal plasma levels of 15-F2α-isoprostane and tHcy showed no significant difference between normozoospermic and asthenozoospermic men. Sperm motility was not correlated with seminal plasma levels of tHcy. No relationship was found between tHcy and lipid peroxidation.

Oral carnitine supplementation increases sperm motility in asthenozoospermic men with normal sperm phospholipid hydroperoxide glutathione peroxidase levels

To clarify the role of carnitine supplementation in idiopathic asthenozoospermia and to look for a rationale for its use in asthenozoospermic patients. Blind clinical study. Academic. Thirty asthenozoospermic patients divided in two groups according to phospholipid hydroperoxide glutathione peroxidase (PHGPx) levels. Placebo for 3 months, then oral L-carnitine (2 g/day) for 3 months; semen samples were collected at baseline, after placebo, after carnitine administration, and again after 3 months with no drugs. Evaluation of seminal parameters and determination of seminal PHGPx levels, measured as rescued activity. When asthenozoospermic subjects were divided in two groups on the basis of PHGPx levels, we observed an improvement of mean sperm motility only in the group of patients with normal PHGPx levels. Phospholipid hydroperoxide glutathione peroxidase has an important role in male infertility, and carnitine treatment might improve sperm motility in the presence of normal mitochondrial function.

Role of seminal osmolarity in the reduction of human sperm motility.

Mammalian sperm at ejaculation are suspended in the seminal plasma, a heterogeneous mixture deriving from the testicular/epididymal fluid and from secretions of seminal vesicles, prostate and bulbourethral glands. Biochemical characteristics of seminal fluid change along the male reproductive tract when considering its inorganic and organic composition and pH but it is known that in each region of the male genital tract seminal osmolarity is higher than that of serum. It has been previously demonstrated that in invertebrate and vertebrate sperm, seminal plasma osmolarity influences sperm motility and activity, and human sperm have been shown to possess osmosensitive calcium entry pathway that controls important functions such as acrosome reaction and oocyte penetration. In the present study, we have determined seminal plasma osmolarity in a large number of normozoospermic fertile and asthenozoospermic infertile subjects correlating it with sperm motility percentages and kinematic characteristics determined utilizing a computerized motion analysis system. Our results confirm that seminal plasma osmolarity is higher than that of serum (336.1 +/- 20.2 vs. 291.1 +/- 6.9 mOsm/L, respectively). Normozoospermic subjects show seminal osmolarity values that are significantly lower with respect to asthenozoospermic patients (317.8 +/- 12.2 vs. 345.2 +/- 22.6 mOsm/L, p<0.001), irrespective of the cause of asthenozoospermia. Seminal plasma osmolarity negatively correlates with sperm progressive motility percentages and kinetic characteristics (curvilinear velocity, linear velocity, linear coefficient and lateral displacements of sperm head). Furthermore, when sperm from fertile subjects were suspended in medium with an osmolarity increasing from 300 to 600 mOsm, sperm motility percentages and kinetics characteristics were progressively reduced and nearly abolished when medium osmolarity was 600 mOsm. On the contrary, when sperm from asthenozoospermic subjects with high semen osmolarity were resuspended in medium with lower osmolarity, sperm motility parameters improved significantly. Sperm motility parameters did not correlate with seminal plasma concentrations of sodium, potassium, chloride with a weak correlation only with seminal calcium concentration. No correlations are present between seminal plasma osmolarity and ionic composition. In conclusion, the present study confirms and extends the knowledge that, in human, seminal plasma osmolarity is higher than that of serum and demonstrates that seminal osmolarity influences sperm motility characteristics and then it may contribute to the pathogenesis of some forms of asthenozoospermia and male infertility.

Seminal plasma nitric oxide concentration in oligo- and/or asthenozoospermic subjects with/without varicocele.

There is an inverse correlation between seminal plasma nitric oxide (NO) concentration and sperm parameters (motility and concentration) in patients with varicocele. This study investigated whether this occurs in patients with oligo- and/or asthenozoospermia due to causes other than varicocele. A total of 69 (19 with varicocele and oligo- and/or asthenozoospermia [group 1], 30 from oligo- and/or asthenozoospermic ones without varicocele [group 2], and 20 from healthy subjects [control group]) semen samples were analyzed. While group 1 had a significantly higher NO concentration in the seminal plasma compared to both the control group and group 2, there was no significant difference between group 2 and the control group (p >.05). In group 1, but not in the other groups, there was an inverse correlation between the seminal plasma NO concentration and sperm motility and concentration. NO production could be specifically related to the varicocele, since NO production in oligo- and/or asthenozoospermia cases without varicocele is not increased.

Correlation of sperm motility with mitochondrial enzymatic activities

AbstractUntil now, little attention has been paid to the contribution of mitochondrial dysfunction to germinal tissue disorders. The target of this study was to investigate the relationship between sperm motility and mitochondrial respiratory chain enzyme activities. The results obtained showed that semen samples of control individuals (n = 33) have substantially higher activities of complexes I, II, and IV compared with those of asthenozoospermic subjects (n = 86). Moreover, a direct and positive correlation was found in the whole population studied between spermatozoa motility and all the mitochondrial respiratory complex activities assayed (I, II, I+III, II+III, and IV). The ratio of these enzymes to citrate synthase (a reliable enzymatic marker of mitochondrial volume) activities did not correlate with sperm motility. This suggests that motility depends largely on the mitochondrial volume within the sperm midpiece. These observations could be of physiopathological relevance because they suggest that factors affecting the mitochondrial energy production could be then responsible for particular cases of idiopathic asthenozoospermia.

Blood concentrations of lead, cadmium, mercury, zinc, and copper and human semen parameters.

The study consisted of 35 male subjects attending an andrology clinic. The subjects all had poor sperm parameters that could not be attributed to any known medical cause. The objective was to evaluate the relation between various seminal characteristics (volume, total sperm count, sperm viability, proportion of progressively motile sperm, and different sperm morphology) and the blood concentrations of lead, cadmium, mercury, copper, and zinc. The mean blood concentrations of lead, mercury, copper, and zinc were within the normal values; cadmium concentration (1.35 micrograms/L) was much higher than the norms. Asthenozoospermic subjects had significantly (p less than .025) higher blood cadmium levels than normozoospermic subjects. No significant differences were noted between the two groups for mean concentration of mercury, zinc, and copper in blood. Significant correlations were observed between blood cadmium levels and volume of semen, midpiece defects, and immature forms of spermatozoa. High blood cadmium levels may have an effect on spermatogenesis. Possible reasons for the high blood cadmium levels among the subjects are discussed.

Epididymal secretory function in men with asthenoteratozoospermia

Epididymal function was evaluated in normozoospermic men and men with asthenoteratozoospermia using alpha-glucosidase as a secretory parameter. No difference was observed in the total quantity of the enzyme secreted into the ejaculate in spite of major differences between the two groups in the proportion of spermatozoa exhibiting progressive motility and normal morphology. In general, the secretion of alpha-glucosidase was positively correlated with the sperm concentration in the normozoospermic group, but not in asthenozoospermic subjects. The total enzyme contents of the ejaculate were significantly greater in men with asthenoteratozoospermia (sperm concentrations, greater than 35 x 10(6)/ml) than in subjects with severe oligoasthenoteratozoospermia (sperm concentrations less than 10 x 10(6)/ml, P less than 0.01) indicating a higher incidence of epididymal occlusion and/or dysfunction in the latter group. Within normozoospermic individuals, extremes in progressive motility or abnormal morphology could not be related to the quantities of enzyme when expressed per million sperm cells. It is concluded that if alpha-glucosidase is a reliable parameter of human epididymal secretory function, variation in the secretory function of the epididymis cannot explain the poor sperm quality observed in asthenoteratozoospermic individuals.

Hyperactivated motility of sperm from fertile donors and asthenozoospermic patients before and after treatment with ionophore

Hyperactivated motility of capacitated sperm was studied before and after contact for 30 min with the Ca2+ ionophore A23187. Sperm from fertile donors and asthenozoospermic infertile patients were incubated in the presence of increasing concentrations of A23187 in the medium. At 5-10 microM, the ionophore induced a significant increase (P less than 0.05) in the percentage of hyperactivation of sperm from asthenozoospermic subjects. Higher concentrations (20 and 30 microM) were needed to enhance hyperactivation of sperm in the fertile population. In the latter, extended contact with the ionophore induced no significant change compared to a 30-min incubation period. Since this type of movement is an essential feature of the fertilizing gamete, a low hyperactivation rate may partly explain fertilization failure in the asthenozoospermic group.