Human sperm motility after migration into, and incubation in, synthetic media

The mechanics of hyperactivation in adhered human sperm

Hyperactivation is an important phenomenon exhibited by mammalian sperm during the process of acquiring fertilization capacity. The majority of studies have focused on incubation-induced hyperactivation in non-human species, which typically differ in size, shape, and are more homogeneous than human sperm. We develop an alternative approach via drug-induction, using high-speed imaging and analysis of same-cell changes in the flagellar movement of adhered cells. Following stimulation with 4-aminopyridine, approximately two-thirds (21 of 34) of the cells analysed exhibited a waveform with a single characteristic frequency; in all cases, the frequency was lower than before stimulation. The remaining cells (13 of 34) exhibited a more complex motility with multiple-frequency modes. The lowest mode in all cases was lower than the frequency prior to stimulation. Flagellar bending increased in all cells following stimulation and was significantly greater in the multiple-frequency responders. Despite the increased bending, time-averaged hydrodynamic power dissipation decreased significantly when assessed across all cells, the effect being significantly greater in the multiple-frequency responders than single frequency. These results reveal the heterogeneity of responses of human sperm to a hyperactivating stimulus, the methodology being potentially useful for assessing dynamic responses to stimuli in human sperm, and physiological selection of cells for assisted reproduction.

Application of Open Source Software Image-J in Microscopic Movement Tracking: Movement Track Reconstruction and Parameter Algorithms

Since movement is an important characteristic of micro-motile cells, the development of microscopic movement tracking techniques is in urgent demand. To meet this need, applications of open source software Image-J in microscopic movement tracking were illustrated with examples. Movement track reconstruction was performed in both circular and linear movement patterns. The algorithms of real time radius, VCL (curvilinear velocity), VAP (average path velocity), VSL (straight line velocity), and other descriptive parameters using original coordinate values were developed and/or explained. Microscopic movement tracking can now be conducted at low cost using Image-J. Moreover, the algorithms can be easily controlled to fit users’ study purpose.

[Sperm hyperactivated motility: influence of the capacitation medium]

OBJECTIVE

Hyperactivation-associated motility is an important marker of capacitation and a prerequisite to fertilization. Computer-Assisted Sperm Analysis (CASA) is a reproducible method that can be used to predict fertilization success, in addition to the migration and survival test. However, published data are contradictory and preparation methods are heterogeneous. Changing one element in the sperm preparation (capacitation medium) may alter its kinetic parameter values.

MATERIAL AND METHOD

This prospective study with two paired series was performed on sperm considered as normal. The sperm preparation was identical up to the second centrifugation, and there after the centrifugate was divided into two groups and suspended either in the capacitating medium Upgraded B2 INRA Medium(R), or in Ferticult Flushing Medium. Measurements were carried out with a Hamilton Thorne Research Analyzer (IVOS v10.9i).

RESULTS

The analysis of the 87 sperm samples included in the study showed differences between the averages of Straight Line Velocity (SLV, p=0.02), Curvilinear Velocity (CLV, p<0.0001), Amplitude of Lateral Head Displacement (ALH, p<0.0001), and algorithmic calculation of the examined hyperactivation (Hyper 5, p<0.0001).

CONCLUSION

The diagnostic validity of hyperactivation motility cannot be dissociated from the preparation conditions. A standardised preparation is a prerequisite for scientific evaluation and validation of this technique. Although higher motility characteristics seem to be desirable in a therapeutic environment, results will have to be validated by clinical tests.

Human sperm-specific peptide vaccine that causes long-term reversible contraception

A novel dodecamer peptide sequence, YLP(12), was identified on human sperm that is involved in oocyte binding. We investigated its immunocontraceptive effects in a murine model. A vaccine was prepared by conjugating the synthetic YLP(12) peptide with the binding subunit of recombinant cholera toxin. Vaccination of female mice by i.m. or intranasal routes without any additional adjuvant induced a sperm-specific immune response in serum and the vaginal tract that caused a long-term contraceptive state. Fertility was fully regained when antibody reactivity diminished at 305-322 days. The contraceptive effect was also completely reversed voluntarily by intravaginal administration of the peptide. Antibodies affected fertility at the prefertilization stage by inhibiting sperm capacitation and the acrosome reaction, and sperm-oocyte binding. The peptide sequence is an epitope of a 50 +/- 5-kDa membrane protein localized on the acrosome and tail of spermatozoa. Thus, the sperm-specific YLP(12) is an attractive candidate for contraceptive vaccine.

Assessment of hyperactivation, acrosome reaction and motility characteristics of spermatozoa from semen of men of proven fertility and unexplained infertility

Semen from men of proven fertility was compared with that of men with unexplained infertility to determine differences in spermatozoal functions such as hyperactivation and acrosome reaction and spermatozoal motility characteristics. The hyperactivated spermatozoa in both groups could be visualised on the monitor of the Computer Assisted Semen Analyser and they exhibited 'circling', 'thrashing', 'starspin' and 'helical' motility patterns and the mean hyperactivation rates were not significantly different. However, 20% of the men with unexplained infertility did not exhibit hyperactivation compared to only 4% in the fertile group. Furthermore, the semen from infertile men when evaluated for hyperactivation could be categorised into two groups with those having lower hyperactivation (< 10% or < 6% after 4 and 6 h of incubation respectively), forming the first group, and those having a higher hyperactivation rate constituting the second group. In the fertile men such distinct groups were not visible and the percentage hyperactivation ranged from 1 to 16%. No significant differences were observed in the rate of acrosome reaction of fertile and unexplained infertile men. The non-hyperactivated spermatozoa from unexplained infertile men showed a significant increase in path velocity (VAP), curvilinear velocity (VCL) and amplitude of lateral head displacement (ALH) and a decrease in linearity (LIN) and straightness (STR) compared to spermatozoa from fertile men. Furthermore, the hyperactivated spermatozoa from infertile men also showed an increase in progressive velocity (VSL) (only after 2 h of incubation) and LIN and decrease in ALH and beat cross frequency (BCF) compared to spermatozoa from fertile men. The results are discussed in the light of the importance of the above spermatozoal functions and spermatozoal parameters in fertilization.

Regulation of human sperm motility and hyperactivation components by calcium, calmodulin, and protein phosphatases

The role of Ca2+, calmodulin, and protein phosphatases on motility and hyperactivation of noncapacitated, capacitating, and detergent-permeabilized reactivated human sperm was examined. In noncapacitated sperm, W7 inhibited percent motility (%MOT), curvilinear velocity (VCL), amplitude of lateral head displacement (ALH), and percent hyperactivation (%HYP) in an extracellular Ca2+ concentration-dependent manner (p < .05). However, in capacitating sperm, inhibition of motility by W7 was independent of external Ca2+. Treatment of reactivated sperm with a synthetic calmodulin inhibitor peptide decreased VCL and ALH in a Ca(2+)-dependent manner (p < .05). Ca2+ exhibited a dramatic influence on motility within a narrow concentration range (0.7 to 1.0 microM) in reactivated sperm. A calmodulin-dependent protein phosphatase (PP2B) was identified by activity assay, immunoblotting, and dephosphorylation of endogenous phosphoproteins. The sperm enzyme, unlike bovine brain PP2B, was inhibited by 1 microM okadaic acid (OA) in the presence of Mn2+, suggesting that the sperm enzyme is unique. In reactivated sperm, inhibition of endogenous PP2B-like activity with anti-PP2B antibodies altered ALH, whereas OA altered both VCL and ALH and also inhibited a subset of Ca(2+)-dependent dephosphorylations of cAMP-dependent phosphoproteins in capacitating sperm. These results suggest (1) an important role for calmodulin and PP2B in Ca(2+)-regulated motility parameters, particularly ALH, and (2) that modulation of human sperm motility, including hyperactivation by cAMP-dependent phosphorylation, requires calmodulin-dependent as well as other protein dephosphorylations.

Functional motion changes during sperm transit to the site of fertilization and in-vitro applications: a review

Continued research to define the parameters of sperm function should aid the evaluation of various approaches in infertility as well as the efficacy of contraceptives for men which do not necessarily achieve azoospermia. Many treatment forms have been advocated for male factor infertility but have yielded little effect. These included, for example, gonadotrophins, clomiphene citrate, the weakly androgenic steroid, mesterolone. Often, improvements in oligoasthenozoospermia that are not related to genital infection, do not attain normozoospermic levels. Owing to lack of success with various treatment modalities, assisted reproductive technology encompassing artificial insemination by husband or donor following in vitro enhancement of sperm function have assumed an important role in male infertility. Agents that have been shown to induce and support sperm capacitation processes such as hyperactivation, could serve an important role. These include human follicular fluid (HFF), maternal serum, fetal cord serum and methyl xanthine derivatives.

An in vitro promoting role for hydrogen peroxide in human sperm capacitation

A complex process of maturation called capacitation is an essential step for spermatozoa to fertilize oocytes. Recent studies have shown that reactive oxygen species (ROS) can enhance the capacitation of human spermatozoa and sperm-zona interaction. We have investigated whether hydrogen peroxide (H2O2) could trigger capacitation of human spermatozoa and the acrosome reaction. The addition of catalase, a specific H2O2 scavenger, at the beginning of the capacitation process decreased the levels of both hyperactivation and induced-acrosome reaction whereas catalase added 15 min before the induction of the acrosome reaction by the calcium ionophore had no effect. Supplementation of the medium with H2O2 resulted in increased levels of hyperactivation and the acrosome reaction, whereas H2O2 added 15 min before induction of the acrosome reaction did not have any stimulatory effect. These results suggest that H2O2 may be involved in the capacitation process of human spermatozoa but not in the acrosome reaction.

Human sperm movement assessed with the Hamilton-Thorn motility analyzer and in vitro fertilization

The relationship between sperm movement characteristics obtained by computerized analysis and the in vitro fertilization rates of human oocytes was studied. In 144 consecutive in vitro fertilization treatments a sample of prepared semen was analysed by a Hamilton-Thorn Motility Analyzer. In addition a visual estimation of sperm count and motility was made. Significant correlations with the fertilization rate were found for all visual parameters. Of the computerized measurements, the mean velocities of motile spermatozoa and the concentration of motile cells were significantly correlated. The average path velocity correlated best (r = 0.42, P < 0.001). There was no relationship between the percentage of motile sperm showing hyperactivated movement and the fertilization rate. A forward stepwise logistic regression analysis selected the following variables of predictive value for fertilization: average path velocity, male factor infertility as indication for in vitro fertilization, motility and concentration, as measured by the Hamilton-Thorn analyzer. A logistic regression model to predict the cases with low (< 0.2) or high fertilization rates, included the average path velocity as a significant variable and classified the samples with 90% overall accuracy.

IN CONCLUSION

movement characteristics of spermatozoa in culture medium, especially the average path velocity are of prognostic value in prediction of human oocyte fertilization rates.

Effects of antioxidants on human sperm preparation techniques

The effect of two different sperm preparation techniques, Percoll gradient centrifugation and swim-up from a washed pellet were tested on the functional competence of the selected spermatozoa. Percoll gradient centrifugation brought about an improvement in sperm motility parameters such as curvilinear velocity and straight-line velocity, an increase in the rates of hyperactivation and the acrosome reaction and an increase in the percentage of motile spermatozoa after 24 h of incubation compared to the centrifugation, swim-up procedure. The effects of antioxidants such as dithiothreitol (DTT) or reduced glutathione (GSH), and reactive oxygen species-scavenging enzymes such as catalase or superoxide dismutase (SOD) during the stage of centrifugation before the swim-up procedure were also studied. Though all of these agents prevented the fall in sperm motility after 24 h incubation, only DTT and SOD improved the rates of both hyperactivation and the acrosome reaction. GSH also improved the acrosome reaction, whereas catalase was without significant effect on the rates of hyperactivation or the acrosome reaction. These results indicate that Percoll gradient centrifugation selects spermatozoa with better functional competence than does centrifugation swim-up. The damage caused by the centrifugation can be prevented by the addition of antioxidants, suggesting that the differences noted with the Percoll gradient method was due to better protection against peroxidative damage due to the centrifugation of unselected spermatozoa. However, the use of DTT is limited by virtue of the fact that this sulphydryl reducing agent leads to destabilization of the sperm chromatin. In contrast, GSH and SOD could have therapeutic potential.

Novel model for study of human sperm chemotaxis

OBJECTIVE

To develop and test an adequate method for the study of sperm chemotaxis.

DESIGN

A model based on a double-chamber design and a matrix of 0.5% hyaluronic acid was used to test the response of human sperm to chemotactic signals from follicular fluid (FF).

RESULTS

A plateau of migration was reached at 10 minutes of incubation; under this condition, 70% of sperm migrated toward chambers with FF, less than 20% to the opposite side, and the rest remained at the site of application. Intra-assay and interassay coefficients of variation using pools of FFs were 17.2% and 23%, respectively.

CONCLUSION

These data confirm previous findings and support the use of this novel model for the study of chemotaxis on human gametes.

Sperm motility analysis using multi-exposure photography (MEP) before and after in vitro-treatment of the semen

Different methods and culture media were used on the same semen samples. Ejaculated and treated samples were evaluated by means of multiple exposure photography (MEP) in order to study changes in sperm motility. A statistical analysis of the normal sperm population distribution curve was done with two objectives: (1) evaluating semen improvement after treatment; and (2) finding out whether the post-treatment sample differed from the original one. When variables were analysed in the individual subject, a significant percentage improvement of mean velocity was observed. Only two methods improved the percentage of motile sperm. The influence of treatment and of culture media on sperm responses was also tested and a significant influence of the media was found (Ham F10 showed the best responses). No significant differences between the ejaculated and treated samples were found when mean velocity, percentage of motile sperm, variance population, and kurtosis were analysed, as grouped treatment variables.

Fertilization failure and dysfunctions as possible causes for human idiopathic infertility

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

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.

Motion of individual human spermatozoa, both normal and lacking the outer dynein arms, during a continuous temperature rise

The effect of increasing temperature from 22-25 degrees C to 37 degrees C on various motion characteristics of individual normal human spermatozoa and spermatozoa lacking the outer dynein arms (LODA) was studied by using a new automatic microscopic tracking method. It was found that: 1) The curvilinear velocity (Vc, measured between 1-3 sec) of both normal and LODA spermatozoa, fluctuated more or less intensely between spermatozoa; this fluctuation was not thermodependent. 2) The average Vc in the two groups of spermatozoa increased with the rise in temperature at a similar rate (1 micron/sec/degrees C), but LODA spermatozoa had an initial Vc lower than that of normal spermatozoa (12.5 +/- 5.3 microns/sec and 34.2 +/- 8.2 microns/sec, respectively). 3) The profile of the Vc increase associated with the temperature rise was different for the two groups of spermatozoa: for LODA spermatozoa it was linear between 25-37 degrees C, whereas for normal spermatozoa a plateau was reached at about 31 degrees C. 4) Various patterns of trajectory were found for both normal and LODA spermatozoa; these patterns were unrelated to temperature. However, LODA spermatozoa had more linear trajectories than normal spermatozoa. 5) Plots derived from reaction rate theory showed that the activation enthalpy, delta H was a function of the increase of Vc for both normal and LODA spermatozoa, but that delta H was higher for LODA spermatozoa.

Follicular fluid-induced acrosome reaction distinguishes a subgroup of men with unexplained infertility not identified by semen analysis

We compared the ability of sperm to undergo follicular fluid-induced acrosome reaction in vitro in fertile men and patients with unexplained infertility. After capacitation under optimum conditions, 28% of sperm from fertile men undergo acrosome reaction after follicular fluid exposure, whereas only 7% of the cells react spontaneously. In 15 men with unexplained infertility, 6 patients showed lack of acrosome reaction, whereas 9 men had sperm acrosome reactions similar to that of fertile men. However, in this cohort under study, semen characteristics of AR(+) and AR(-) patients were similar. In addition to inducing sperm acrosome reaction, follicular fluid also promoted significant changes in motion characteristics of capacitated sperm. Sperm curvilinear velocity (Vc) increased significantly after exposure to follicular fluid though linearity remained unchanged. The largest difference in cumulative Vc occurred at 90 microns/s. Assessing the ability of capacitated sperm to acrosome react may have clinical significance in predicting whether such sperm are capable of fertilizing an ovum.

Human sperm mitochondrial function related to motility: a flow and image cytometric assessment

Current evaluation of male fertility, routinely estimated by sperm count, motility, and morphology, provides only crude information about the fertility state of individuals. Both flow and image cytometry were applied to mitochondrial activity and sperm motility respectively. Sperm samples from fertile donors were concomitantly measured for Rhodamine 123 (Rh123) uptake (an estimation of mitochondrial activity), percentage of dead cells, and motility characteristics, such as percentage of motility, curvilinear velocity, and amplitude of lateral head displacement. These measurements were done under experimental conditions known to modulate sperm motility (temperature and time course survival in a capacitating medium). Bimodal distributions were found for Rh123 uptake. Flow cytometry-derived parameters were essentially time-dependent whereas motility characteristics were primarily temperature-dependent. Correlations were found between various flow cytometry-derived parameters and motility characteristics. Most of the correlations were obtained after a 24 h incubation in a capacitating medium. The most significant correlation in every experimental condition concerned the percentage of motile spermatozoa and the Rh123 uptakes. The drop in motility observed after a 24 h incubation was paralleled by a markedly lower drop in mitochondrial activity. The data suggest that these two complementary techniques represent an improvement in basic and/or clinical assessment of the functional spermatozoa status.

Does computerized image analysis of sperm movement enhance the predictive value of semen analysis for in-vitro fertilization results?

The influence of semen quality on fertilization rates in an in-vitro fertilization (IVF) programme was studied by analysing both conventional semen parameters and computerized movement characteristics. The study was based on 407 inseminated oocytes which were obtained from 50 patients in 113 laparoscopies. Sperm concentration did not correlate strongly with the fertilization rate. Sperm motility and morphology were the most meaningful parameters in predicting fertilization success. A drop in fertilization rate was found when sperm motility or normal morphology were below 40%. Sperm velocity measured in semen was the only sperm movement parameter which correlated with the fertilization rate, albeit weakly. The latter was reduced when average sperm velocity in semen was less than 50 microns/sec. Conventional semen parameters seem to be more predictive of the fertilizing potential of an ejaculate than movement characteristics obtained by computerized image analysis.

Acrosomal function of human spermatozoa with normal and abnormal head morphology

In previous studies we have shown differences in the function of morphologically normal and abnormal sperm by evaluating their flagellar movements and swimming trajectories. In this study we have compared the capability of morphologically normal and abnormal human sperm to undergo an acrosome reaction after incubation with human follicular fluid. Semen samples were studied from 6 research donors and 21 semen evaluation patients. All men had normal semen by clinical criteria. Semen was prepared either by a two-step Percoll gradient centrifugation or the sperm were diluted, washed, and centrifuged three times. Sperm suspensions were incubated for 24 hours in a modified Tyrode's medium, containing 2.6% bovine serum albumin, prior to dilution with human follicular fluid. The percentage of acrosome reactions among viable sperm was assessed after 15 minutes using the supravital Hoescht stain and fluoresceinated pea lectin. Sperm head size was measured with an ocular micrometer and normal values were defined as length 3-5 microns and width 2-3 microns. At least 25 viable normal sperm, and 25 viable abnormal sperm were analyzed for acrosome reactions on each slide. With Percoll separation the percentage of acrosome reactions (mean +/- sem) for normal sperm was 38 +/- 3% vs. 22 +/- 2% for abnormal sperm (P less than 0.005). After washing, the comparable values were 12 +/- 1% vs. 5 +/- 1% (P less than 0.005). The incidence of spontaneous acrosome reactions (24 hours of incubation, no follicular fluid) was also higher for normal sperm than abnormal sperm (9 +/- 1% vs. 4 +/- 1%, P less than 0.01). These data demonstrate an association between normal sperm morphology and acrosomal function.

Comparison of two techniques used to collect normal and motile sperm

To improve the quality of sperm for intra-uterine insemination (IUI) or in-vitro fertilization (IVF) swim-up (SU) and migration-sedimentation (MS) methods were compared, for the selection of morphologically normal and motile sperm. In 74 patients consulting for couple infertility, it was shown that MS gave a better yield of motile sperm than did SU. An improvement in morphology and motility was achieved, especially in asthenospermia (motility less than 40%) and/or teratospermia (normal shape less than 40%). The percentage of midpiece and tail abnormalities was lowered by the MS technique. It is proposed that the MS method be used for IUI and IVF, adapting the number of tubes to the initial sperm concentration.

Measurement of spermatozoal motility over prolonged periods of time using image analysis

This paper presents a new method for the quantitative analysis of the movement characteristics of spermatozoa. The method is based on (i) measuring the displacement of a spermatozoon observed using a microscope and (ii) automatically compensating for the displacement of the spermatozoon in order to keep it in the center of the microscopic field. The displacement of the spermatozoon is measured by on-line processing of digitized images of the microscopic field, acquired by an image analysis system. The motility characteristics of the same spermatozoon can be evaluated over prolonged periods of time (typically 10 min). The movement characteristics of 19 spermatozoa from five fertile donors were studied. At constant temperature, intradonor variations of the motility parameters were found. No statistically significant differences were found in the mean values of the motility characteristics for three of four donors. At increasing temperature, the mean curvilinear velocity, averaged on the 19 spermatozoa from the five donors, regularly increased between 23 and 30 degrees C and remained constant up to 38 degrees C.

A computer-assisted assay for mouse sperm hyperactivation demonstrates that bicarbonate but not bovine serum albumin is required

Mammalian sperm hyperactivation (HA) is a change in motility that accompanies capacitation (CAP) and is dependent on calcium (Ca) (Yanagimachi and Usui, Exp Cell Res 89:161, 1974). HA may be important for transport through the female tract and/or for fertilization. To develop an objective and quantitative assay for HA in individual mouse sperm, a computer-assisted motion-analysis system was used to describe sperm translational movements. To determine which movements were characteristic of HA, Ca-dependent motility was identified. This was done by incubating sperm with or without calcium (Ca+ or Ca- sperm, respectively), and determining the range of values for each motility parameter that was present only among Ca+ sperm. To do this, we compared frequency distributions of motility parameter values at the time of maximal CAP (90 min). CAP was monitored by measuring the level of in vitro fertilization and by evaluating the pattern of chlortetracycline binding to individual sperm heads [Ward and Storey, Dev Biol 104:287, 1984]. Two Ca-dependent motility subgroups were apparent: 1) a "slow-speed" subgroup with a curvilinear velocity (Vc) less than 169 microns/sec that had none of the characteristics expected of HA sperm; and 2) a subgroup with higher speeds (Vc greater than 169 microns/sec) and wider-amplitude head movements as measured by curvilinear progressiveness ratio (PRc less than 0.56). The latter subgroup was selected as HA, since the frequencies and time course were similar to those for CAP in the same population. Two media components known to be important for CAP, bicarbonate and bovine serum albumin (BSA) were then tested to determine whether they were necessary for HA. Incubation of sperm without bicarbonate prevented HA, but omitting BSA did not affect HA during the first 3 hrs. These data suggest that HA is not tightly coupled with CAP.

Efficacy of commercial condoms in the prevention of hepatitis B virus infection

Tips of synthetic and natural condoms were filled with serum samples containing either hepatitis B virus, herpes simplex virus, or cytomegalovirus, then fit over an 8-in. mechanical vibrator and inserted vibrating into sterile bath solutions for 30 min. Phosphorus 32-labeled hepatitis B and cytomegalovirus molecular probes and viral culture techniques for herpes simplex and cytomegalovirus were used to determine whether leakage of virus had occurred into the surrounding bath solutions. Natural condoms allowed leakage of hepatitis B virus but not herpes simplex virus or cytomegalovirus, whereas synthetic condoms prevented leakage of all viruses. These results suggest that natural condoms might not be effective in preventing sexually transmitted hepatitis B virus infection.

Increase in progressive motility and improved morphology of human spermatozoa following their migration through Percoll gradients

Human spermatozoa were separated on the basis of their motility in a discontinuous Percoll-gradient made up in tissue culture medium containing 10% (v/v) human serum (TCMS). Portions of ejaculates were placed on top of the gradients. After 3 h at 37 degrees C the bottom 1.5 ml was collected and the sperm washed free of the Percoll solution by centrifugation at 240 X g after dilution in TCMS. In this way the spermatozoa were separated from seminal fluid by means of the swimming rate of the sperm. When semen samples from normal men were used, total recovery of sperm after separated on a Percoll gradient was 21 +/- 2.3%. The progressive motility index increased by a factor of 15 +/- 1 when comparing separated samples with the same unseparated ejaculate, and the frequency of sperm with normal morphology increased from 60 to 85%. The improvements in these semen samples was attributable to the Percoll separation as the washing procedure itself was without effect. Using this method sperm of relatively unifirm motility and morphology can be collected. These may then be used for further biochemical and physiological studies. Improved sperm quality was also obtained when samples from patients with abnormal semen profiles were separated in this way, although the degree of improvement was much more variable than that obtained with semen from normal fertile men. This indicates that this method can be used in clinical practice in selected cases for the preparation of sperm for insemination or for in-vitro fertilization.

Research frontiers in human in vitro fertilization

The acceptance of IVF-ET as a treatment modality for certain types of infertility in the human has triggered a flurry of activity in providing a patient service, in applied research endeavors designed primarily to improve clinical pregnancy rates and in basic research in reproductive endocrinology and physiology. This paper outlines the state of the art in technologic and research frontiers associated with these endeavors.

Hyperactivation of human spermatozoa: measurement of motility before and after incubation

The motility rate of sperm during capacitation process was determined by calculating a sperm motile efficiency index (SMEI) using a hemocytometer. The SMEI values for the sperm from 100% of normal fertile men and 64% of infertile patients increased significantly by the fourth hour of incubation, while for 36% of infertile patients there was no increase. A correlation between the increase of SMEI and original motility, original SMEI and original semen amount was not possible. In addition, a decrease of the SMEI value was observed after sperm incubated for 3 hours were added to the seminal plasma of the donor. It is concluded that in human spermatozoa "hyperactivation and dehyperactivation" can be measured by SMEI.

Effect of migration and capacitation on the nuclear stability of human sperm

A possible change in the nuclear stability of the human spermatozoa further than ejaculation was investigated. A nuclear chromatin decondensation ability test using 1% SDS + 6 mM EDTA was used on spermatozoa migrated for 1 h in a swim-up migration (in BWW + human serum albumin 0.8%) and capacitated for 5 h in the same medium. The results, analyzed as paired series, showed that (1) capacitated and migrated spermatozoa have a greater nuclear stability than that of the control population (total sperm), (2) there was no significant difference of the nuclear stability between migrated and capacitated spermatozoa, and (3) there was no effect of the media used (BWW + HSA) on the nuclear stability. Thus, it seemed that migrating spermatozoa definitely selects a specific resistant population to decondensing reagents.