The correlates of fertilizing capacity in normal fertile men

Transmembrane migration technique: reexamination of its usefulness in sperm motility assessments

A study was carried out using time-exposure photomicrography to investigate the potential usefulness of the transmembrane migration technique in the assessment of drug effects on human sperm motility. Significant but weak correlations were evident between the transmembrane migration ratio (TMMR%) and both % motility (r = 0.43; p less than 0.05) and the amplitude of lateral sperm head displacement (r = 0.40; p less than 0.05). However, no significant correlations were evident between TMMR% and the concentration of motile spermatozoa, mean path velocity, or frequency of sperm head rotation. Exposure to 2.5 mM 2-deoxyadenosine caused significant increases in % motility, mean path velocity, and frequency of sperm head rotation, with no concomitant rise in TMMR%, while 5.0 mM caffeine caused significant elevations in both TMMR% and in % motile cells. It is concluded that the transmembrane migration technique is a relatively insensitive method for detecting subtle but important changes in the movement characteristics of human spermatozoa.

Bovine spermatozoa as an in vitro model for studies on the cytotoxicity of chemicals: effects of chlorophenols

The suitability of ejaculated bovine spermatozoa as an in vitro model for the assessment of the cytotoxic potential of chemicals was evaluated using several endpoints: swimming activity, adenine nucleotide content, membrane integrity and oxygen consumption. A series of chlorophenols inhibited sperm motion (motility and velocity) in a concentration-dependent manner. This could be determined quantitatively and reproducibly by means of videomicrography and automatic computer image analysis. The sperm immobilizing potency increased with increasing chlorination and was positively correlated with lipophilicity. Concentrations which reduced the percentage of moving sperm to 50% of controls ranged from 43 microM for pentachlorophenol (PCP) to 1440 microM for 4-monochlorophenol (4-MCP). Determinations of adenine nucleotides and percentages of viable cells revealed qualitative differences between the action of PCP and the lower chlorinated phenols. While the latter decreased the total adenine nucleotide contents and the percentage of unstained cells in parallel to motion inhibition, no such changes occurred after exposure to immobilizing concentrations of PCP. Penta-, tetra- and trichlorinated phenols stimulated cellular respiration, indicating their uncoupling activity, at concentrations lower than those necessary for motion inhibition. The results indicate that bovine spermatozoa may become a useful in vitro model for the toxicological evaluation of chemicals providing quantitative as well as qualitative data.

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.

Glass wool-filtered spermatozoa and their oocyte penetrating capacity

The capacity of glass wool-filtered spermatozoa to penetrate zona-free hamster oocytes was studied. As compared to prefiltered sperm samples, oocyte penetration was significantly increased. A significant increase in the penetration rate for the filtered sperm population was noted even after the sperm motility in the filtrate was adjusted with medium equal to that of the prefiltered sample. However, no significant differences in oocyte penetration were seen between the prefiltered and the filtered sperm population when the filtered sperm samples were diluted with nonviable spermatozoa. These results show that glass wool filtration yields a sperm population with a greater penetrating capacity. It was concluded that motility alone could not account for the improved penetrability and that the removal of nonviable spermatozoa may at least, in part, be responsible for this effect.

Preincubation of human spermatozoa in test-yolk medium: effect on penetration of zona-free hamster oocytes and correlation with other semen characteristics

Penetration of zona-free hamster oocytes by human spermatozoa after preincubation with BWW medium (standard technique) or a buffer system containing egg yolk (TESTY) was compared by applying both treatments to aliquots of 60 ejaculates from 34 patients. The TESTY-treated spermatozoa penetrated the oocytes much more successfully than the spermatozoa treated by the standard technique. Although the penetration levels achieved by the two methods were significantly correlated, the correlation coefficient was too low to predict the penetration outcome from one technique to the other. More consistent results were obtained when different ejaculates from the same donor were treated by TESTY than by the standard technique. Spermatozoan penetrating ability was more strongly correlated with sperm concentration, motility, and morphology after treatment by the standard technique than after TESTY treatment. Much larger differences in penetration were present between normal and abnormal ejaculates when the standard technique was used than TESTY.

Effects of extracellular ionized calcium, diltiazem and cAMP on motility of human spermatozoa

In order to elucidate the effects of ionized calcium and calcium channel blockers on human sperm motility, an in vitro study was conducted looking at the effects of exogenous calcium, ethylene diamine tetraacetic acid (EDTA), diltiazem and dibutyrl cyclic adenosine monophosphate (db-cAMP) on per cent motility and mean velocity of human sperm. Washed spermatozoa from 21 fertile donors were incubated with ionized calcium (zero, five, 10 and 50 mM), EDTA (one and 10 mM), diltiazem (one, 10, 100 microM and one mM) and cAMP (five mM). Per cent motility and mean velocity determinations were made at 10 and 120 min. by computerized analysis of videomicrographs. Over a wide range of extracellular ionized calcium concentrations (50 microM to 50 mM), per cent motility and mean velocity of human sperm were not stimulated or inhibited. At ionized calcium concentration less than 1 microM, achieved by addition of EDTA (10 mM), per cent motility decreased by 68% and 79% and mean velocity decreased by 44% and 48% compared to controls at 10 and 120 min. respectively (p less than 0.001). The decrease in mean velocity was reversible by addition of calcium to the EDTA (10 mM) sample to return ionized calcium to control concentration (0.5 mM). This reversibility suggests EDTA did not have a direct toxic effect on spermatozoa and that its action was mediated by changes in ionized calcium concentration. Diltiazem (one mM) decreased sperm mean velocity by 26% and 28% compared to controls at 10 and 120 min. respectively (p less than 0.01), but had no effect at lower concentrations (one, 10 or 100 microM). Db-cAMP (five mM) increased per cent motility by 25% and 20% and mean velocity by 36% and 34% compared to controls at 10 and 120 min. respectively (p less than 0.05). These results indicate that a minimum level of extracellular ionized calcium is essential to normal sperm motility and suggest that sperm are more dependent on the intracellular translocation of calcium ions for the regulation of motility than on the extracellular ionized calcium concentration. While db-cAMP does significantly increase per cent motility and mean velocity of human sperm, its clinical usefulness for the treatment of male infertility remains to be demonstrated.

Analysis of the relationship between defective sperm function and the generation of reactive oxygen species in cases of oligozoospermia

The ability of human spermatozoa to exhibit sperm-oocyte fusion in response to the ionophore, A23187, was examined in relation to the capacity of these cells to generate reactive oxygen species. In 70 fertile control donors, there was an overwhelming pattern of high levels of sperm-oocyte fusion associated with low levels of reactive oxygen species production. By contrast, 88% of the 74 oligozoospermic patients exhibited less than 25% oocyte penetration in response to A23187 and 58% exhibited no penetration whatsoever. Of the 40 oligozoospermic patients who failed to respond to A23187, nine had low levels of reactive oxygen species production in association with impaired liquefaction of seminal plasma. Of the remainder, 17 (55%) exhibited defective sperm function together with elevated production of reactive oxygen species. These observations, which are the first to describe a biochemical defect in the spermatozoa of oligozoospermic patients, may carry significant implications for the etiology and treatment of this condition.

Factors regulating mammalian sperm migration through the female reproductive tract and oocyte vestments

Mechanisms of mammalian sperm migration through the female reproductive tract and ovum vestments are described. The perspective is biophysical as well as biochemical and morphological, and the focus is upon the role of sperm motility in these processes. Sperm forward progression is characterized as an interactive process between the the cell and its environment, and the mediation of flagellar bend propagation by the physical properties of its surroundings is described. These properties, together with flagellar beat kinematics, sperm morphology, and surface properties, determine the magnitude of the forces generated by sperm and their consequent rate of progression. Sperm interactions with the cervical mucus, the cumulus oophorus, and the zona pellucida are described. The poorly understood affinity of the sperm surface for the macromolecules of the mucus, cumulus, and zona is stressed, as is the viscoelastic structural mechanical resistance of these biopolymers to sperm motion. The kinematics and consequences of hyperactivated sperm motion are presented, with emphasis on objective characterization of such motion (as a biomarker), along with analysis of the mechanical advantage that such motion may confer on spermatozoa during egg-vestment interaction.

Evaluation of computerized analysis of sperm movement characteristics and differential sperm tail swelling patterns in predicting human sperm in vitro fertilizing capacity

Multivariate discriminant analysis was used to evaluate the usefulness of computer image analysis of sperm movement characteristics and differential patterns of sperm tail swelling after hypoosmotic treatment for predicting the human sperm in vitro fertilizing capacity assessed by the zona-free hamster egg penetration assay. Fifty-five semen samples, mostly normospermic, from untreated infertility clinic patients were analyzed. The % normal sperm morphology, linearity of seminal sperm movement, seminal sperm head beat frequency, mean and maximum amplitudes of lateral head displacement, and hypoosmotic sperm tail swelling patterns c, d and f were selected by multivariate discriminant analysis to be capable of discriminating the samples exhibiting the presence or the absence of sperm in vitro fertilizing capacity. The % total sperm tail swelling did not give additional information about in vitro fertilizing capacity. These preliminary data suggest that computer image analysis of sperm movement characteristics and differential evaluation of hypoosmotic sperm tail swelling might be useful for the prediction of human sperm fertility. Further prospective studies are necessary to validate their predictive functions.

Semen characteristics of Vietnam veterans

As part of an epidemiologic study of the health status of a randomly selected group of Vietnam veterans, we measured the semen characteristics of 324 Vietnam veterans and compared them with a similar group of 247 veterans who did not serve in Vietnam. The participation rate was 81% in both groups. Measurements of sperm concentration, movement characteristics, and head dimensions were performed, using the Cellsoft computer-assisted semen analysis system. We found that Vietnam veterans had significantly (p less than 0.05) lowered mean sperm concentrations (64.8 x 10(6) sperm/mL for Vietnam veterans vs 79.8 x 10(6) sperm/mL for non-Vietnam veterans), and Vietnam veterans were twice as likely to have sperm concentrations less than or equal to 20 million/mL (odds ratio = 2.7, 95% confidence interval = 1.3-5.7). Vietnam veterans also had a significantly lowered mean proportion of morphologically normal sperm heads (57.9% vs 60.8%), with significantly longer mean major axis length and head circumference. The proportion of motile cells, velocity, linearity, amplitude of lateral head displacement, and beat frequency were not different between the two groups. Despite differences in sperm characteristics, Vietnam and non-Vietnam veterans reported fathering similar numbers of children.

Significance of reactive oxygen species and antioxidants in defining the efficacy of sperm preparation techniques

The mechanisms responsible for mediating the influence of sperm preparation protocols on human sperm function have been investigated. Techniques that involved the separation of motile spermatozoa prior to centrifugation were found to yield sperm suspensions of highest quality. If the spermatozoa were centrifuged prior to isolation of the motile cells, sperm function was impaired. The detrimental effects of centrifugation were associated with a sudden burst of reactive oxygen species production by a discrete subpopulation of cells (characterized by significantly diminished motility and fertilizing capacity) that could be separated from normal functional spermatozoa on Percoll gradients. If unfractionated sperm suspensions were subjected to centrifugation, the reactive oxygen species generated by this subpopulation impaired the functional competence of normal spermatozoa in the same suspension. Assessment of the ability of the antioxidants, butylated hydroxytoluene, and vitamin E, to curtail the peroxidative damage inflicted by such cells in response to centrifugation revealed a significant improvement of sperm function in the presence of vitamin E.

Capacity of objectively assessed sperm motility characteristics in differentiating between semen of fertile and subfertile men

A simple and inexpensive computer-assisted method for the objective assessment of sperm motility characteristics was employed to evaluate semen samples of 42 fertile men and 70 subfertile patients. The capacity of each motility parameter to discriminate between semen of the two groups was evaluated by receiver operating characteristic curve analysis. Velocity, linear velocity, and "angular" velocity are reasonably accurate, whereas linearity and angularity index had a very poor discriminating power. The best discrimination between the two groups was the proportion and concentration of sperm with rapid linear progressive motility, based on the cut-off value of linear velocity greater than or equal to 22 microns/sec. This parameter was 90% accurate in discriminating semen of infertile men from that of subfertile patients.

Analysis of calmodulin acceptor proteins and the influence of calmodulin antagonists on human spermatozoa

The possible role of calmodulin in regulating a number of calcium-dependent functions exhibited by human spermatozoa was investigated by using the antagonists trifluoperazine and calmidazolium. At high doses both antagonists inhibited the motility of human spermatozoa and induced a concomitant rise in [Ca2+]i and a decline in cAMP. Lower doses of these antagonists, particularly calmidazolium, suppressed the ability of human spermatozoa to generate reactive oxygen species and exhibit sperm-oocyte fusion, without influencing [Ca2+]i, cAMP, or motility. This inhibition of sperm-oocyte fusion was effective even if the spermatozoa were subsequently exposed to A23187, suggesting that calmodulin may regulate this aspect of human sperm function at a point downstream from calcium influx. Both radiolabelling and affinity chromatography techniques were used to detect a number of calcium-dependent and calcium-independent calmodulin acceptor proteins in the human spermatozoon. The major calcium-dependent acceptor proteins exhibited Mr values of 32,000 and 22,000-27,000, respectively, and did not appear to be associated with the sperm plasma membrane.

Validation of a single-step procedure for the objective assessment of sperm motility characteristics

A relatively cheap method is described for the objective assessment of sperm concentration and motility characteristics. The method uses a digitizing tablet with cursor, a micro-computer and a phase-contrast or dark-field microscope equipped with a drawing tube. With this technique the following are accurately assessed: sperm concentration, percentage motility, motility grading, concentration of grade a motile spermatozoa, sperm velocity, linear velocity, linearity and angularity. The data are acquired in less than 5 min. Validation studies reveal this method to be accurate, reproducible (coefficient of variation of motility characteristics = less than 7%) and clinically useful.

Influence of image sampling frequency on the perceived movement characteristics of progressively motile human spermatozoa

Tracks of 30 progressively motile washed human spermatozoa were plotted manually from 200-Hz frame rate video recordings. Tracks at 100, 66.7, 50, 40, 33.3, 25, 20, 10, and 5 Hz were then constructed using every 2nd, 3rd, 4th, 5th, 6th, 8th, 10th, 20th, or 40th point. The 200-Hz tracks were analyzed by traditional manual methods, and all ten sets of tracks analyzed using a computer-assisted method ("Videomot," developed originally to analyze 30-Hz tracks) to eliminate observer bias. Progression velocity (VSL) remained constant under all analysis conditions. Average path velocity (VAP) also remained essentially constant, although Videomot was less reliable at high frame rates due to problems in determining the average path. Curvilinear velocity (VCL) was very frame rate dependent (the 25-Hz mean value was only 56.5% of that at 200 Hz), and Videomot was more accurate than manual analysis at 200 Hz. Values of the amplitude of lateral head displacement (ALH) were acceptable at most frame rates. At less than 66.7 Hz the inclusion of spurious curvilinear track deviations caused lower mean ALH values, and at 5 Hz ALH could not be measured since the track was essentially the average path. Beat/cross frequency (BCF) was also frame rate dependent; at high rates there was the same problem as with ALH measurements, while at less than or equal to 25 Hz the maximum BCF was restricted by the frame rate. We conclude that human sperm movement characteristics can be measured at frame rates ca. 30 Hz but only if the constraints affecting VCL and BCF values are understood and accepted. Finally, less than 10 Hz can only give values for VSL and, perhaps, VAP.

Evaluation of sperm motility by optical diffractometry of spermatograms

Evaluation of sperm motility based on analysis of spermatograms by optical diffractometry was performed. Spermatograms are defined as images of sperm tracks obtained on microphotographs by dark field illumination with long exposure time. Single track analysis proved that the details concerning single tracks are "seen" and recognized by the technique of optical diffractometry. Normal "linear", as well as abnormal "irregular", including "circular", tracks were numerically described. Multitrack analysis: The general pattern of all tracks contained in particular spermatograms derived from two groups of semen classified by hospital laboratory as "high" (control) and "low" ("mediocre") motility of spermatozoa, respectively, were analysed by optical diffractometry. The hospital laboratory was asked to provide for diffractometric analysis samples of the "mediocre" semens of quality similar enough to the "control" ones what concerns the percentage of motile spermatozoa (40 percent) and spermatozoan concentration. Diffraction patterns of 102 spermatograms of control sperm and of 103 spermatograms of sperm qualified as "mediocre" by subjective microscopic evaluation of sperm motility, were analysed and compared. Using discriminant analysis based on parameters describing radial distribution of light intensity in diffraction patterns of control and "mediocre" spermatograms, it was possible to classify correctly 71 cases as high motility sperms out of 102 spermatograms evaluated beforehand by hospital laboratory criteria as control ones. In the group of 103 spermatograms classified as "mediocre" sperms by hospital laboratory criteria 69 cases were correctly recognized as "mediocre" by diffractometric analysis. The overlapping of the analysed two groups of sperm by 30 percent might be explained by the fact that in the control spermatograms many trajectories are formed by inefficient, slow moving spermatozoa.(ABSTRACT TRUNCATED AT 250 WORDS)

The human sperm-hamster egg penetration assay: prognostic value

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

Sperm morphology by image analysis compared with subjective assessment

Human sperm heads were detected and tracked using semi-automatic image analysis. Six measurements of size and shape were computed from two samples of semen from each of 26 men. Subjective assessments of abnormal morphological forms were made on the same samples by two independent assessors. A formula for prediction of percentage abnormality was calculated from the results. The subjective assessment of abnormality was related primarily to the number of elongated heads and secondly to the number of small heads. Computed image processing provides an objective method for measurement of the morphological features of sperm.

Computerized videomicrographic analysis of rat sperm motility

Quantitative methods for the determination of the concentration, percent motility and swimming speed of human and animal spermatozoa can assist in the objective analysis of sperm and semen quality. These parameters are among the most discriminating indicators for both clinical and toxicologic assessments of reproductive function. A computerized videomicrographic analysis system to measure sperm motility characteristics in the Fischer 344 rat was characterized and compared with both manual and semi-automated videomicrographic methods (Blazak et al, 1985). The system compares favorably, both in accuracy and sensitivity, to these more conventional methods. The most variable indicator of potential reproductive function in the Fischer 344 rat is the total sperm count from the cauda epididymidis (coefficient of variation [CV] = 24%), while parameters of sperm motility vary least. These include percentage of motile cells (CV = 15%), curvilinear velocity (CV = 9%) and linearity (CV = 10%), which is a ratio of straight-line to total distance traveled. It was concluded that the computerized system may be useful for routine assessment of changes in sperm quality that may occur in the rat after exposure to toxic drugs or chemicals.

Penetration ability of human spermatozoa into standardized bovine cervical mucus (Penetrak) in patients with normal and pathological semen samples

Semen samples from 89 men were analyzed and evaluated with a standardized bovine cervical mucus penetration test (Penetrak). 29 patients had a normozoospermia, 22 patients a teratozoospermia and 38 patients an oligozoospermia of various degree. The most important parameters of semen analysis were compared with sperm mucus penetration. The sperm mucus penetration test correlated best with progressive motility (r = 0.6758), followed by total motility (r = 0.6302), sperm count (r = 0.6190), and % normal spermatozoa (r = 0.5493) (p less than 0.01 for each correlation coefficient). In the group of patients with normozoospermia 6 cases had been detected with insufficient sperm mucus penetration and in both groups with subfertility 15 cases with adequate sperm mucus penetration. 8 semen samples with normal sperm count and normal sperm motility were used for IVF. Only 6 patients with normal sperm penetration (greater than 30 mm/90') the spermatozoa fertilized the ova, but not from two patients, who had a sperm mucus penetration of less than 30 mm/90'. The study demonstrated that standardized bovine mucus penetration test detects disturbances of sperm motility which may not be discovered by conventional semen analysis.

Importance of sperm motility after capacitation in interpreting the hamster ovum sperm penetration assay

Routine semen analysis and a zona-free hamster ovum sperm penetration assay (SPA) were carried out for 220 men from a group of infertile couples. The grade of sperm motility was determined after a preincubation period. For both the normal and abnormal semen samples, the number of positive SPAs was significantly higher when the postcapacitation motility was normal. This difference was observed also when the routine semen characteristics of density, motility, and morphologic features were considered separately regarding their relationship with the SPA. Motility after preincubation showed the most significant positive correlation with the SPA result. Therefore, the SPA score should be limited to semen samples showing adequate postincubation motility.

Correlation between in vitro fertilization and human sperm density and motility

The conventional sperm characteristics of density (millions per milliliter) and motility, scored in a semi-subjective way, were correlated with results of an on-going in vitro fertilization and embryo transfer program. No male infertility patients were included in this study. Individual characteristics of the "successful" ejaculates are described. Sperm densities in the original ejaculate of more than 10 X 10(6) spermatozoa/ml did not significantly improve outcome (P less than 0.01). In contrast, sperm motility seemed to play the most important role, since most pregnancies (12/14) occurred using sperm samples with greater than or equal to 60% total motility (P less than 0.001). The incidence of multipronuclear fertilization is also described and discussed. These data, which were collected during 1984 in the in vitro fertilization unit of Professor R. Schoysman and coworkers (Vilvoorde, Brussels), may help to make fertilization in vitro and embryo transfer a viable method in cases of mild male subfertility, and to provide guidance in preparing some couples for the combined use of husband and donor semen if a sufficient number of oocytes are obtained.

Morphometric analysis of spermatozoa in the assessment of human male fertility

A videomicrographic system was developed for measurement of morphometric parameters of human spermatozoa. Contours of the images of spermatozoa on a video monitor are digitized by manually tracing them with the cursor of an electromagnetic digitizer integrated to a microcomputer. The accuracy and precision of the methodology were evaluated. A comparison of human sperm heads in shallow wet preparations and in dried, stained preparations indicated that the latter were smaller in length, width, projected area, and circumference, but that the ratio length/width was not different. An analysis was made of 457 ejaculates from 16 fertile donors. The variation between ejaculates within donors was similar in magnitude to the variation between donors. A study was performed comparing seminal sperm morphometry in single specimens from 30 fertile and 30 infertile men. The sperm head length/width ratio was the parameter that differed the most between these two groups. Moreover, it was the per-ejaculate variability of this parameter, rather than the central tendency, that maximized the difference.

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

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

Factors influencing the success of sperm-cervical mucus interaction in patients exhibiting unexplained infertility

The factors regulating the success of sperm-cervical mucus interaction in 46 patients exhibiting unexplained infertility were analyzed. Within this group of patients, considerable variation in the degree of mucus penetration, which appeared to be related to the properties exhibited by the spermatozoa rather than the quality of the mucus itself, was observed. The ability of the spermatozoa to fuse with zona-free hamster oocytes reflected their capacity for mucus penetration, regardless of whether human or bovine cervical mucus was used as the target. Multiple regression analysis also indicated the importance of the movement characteristics exhibited by the spermatozoa, which alone could account for up to 85% of the variability in mucus penetration. The concentration of motile spermatozoa and their linear velocity of progression influenced the number of spermatozoa penetrating the mucus in unit time, presumably through an effect on the frequency of collisions at the cervical mucus interface. Whether these collisions resulted in mucus penetration depended upon the movement characteristics of the spermatozoa and was positively associated with a "rolling" mode of progression and the amplitude of lateral sperm head displacement.

The value of adenosine triphosphate (ATP) measurements in assessing the fertilizing ability of human spermatozoa

A study was undertaken to examine the relationship between adenosine triphosphate (ATP) levels and the fertilizing capacity of human spermatozoa in vitro and in vivo. The concentration of ATP in semen was found to be positively correlated with the ability of sperm to fuse with zona-free hamster oocytes. However, it was also demonstrated that a large part of this relationship depends upon the relationship between semen ATP concentrations and sperm number. Measurements of ATP levels in cryostored ejaculates used in an artificial insemination by donor program revealed that such measurements were not able to distinguish fertile from infertile ejaculates. However, among fertile donors, ATP levels did seem to contribute useful information on relative fertility. It is concluded that ATP measurement has a limited role in the laboratory evaluation of sperm function.

Diagnostic value of the zona-free hamster oocyte penetration test and sperm movement characteristics in oligozoospermia

A group of 27 oligozoospermic patients were followed up for 4.2 +/- 1.1 years in a prospective study designed to determine which aspects of semen quality are of value in the diagnosis of fertility. The semen analysis included the zona-free hamster oocyte penetration test, the assessment of sperm movement characteristics by time exposure photomicrography and a conventional semen profile. During the follow up period, 7 patients (25.9%) initiated a pregnancy. The identity of these fertile subjects could not have been ascertained by any single criterion of sperm movement or any feature of the conventional semen profile. The zona-free hamster egg penetration rates were also of little value in this respect since 4 of the 7 fertile patients scored 0% in this assay. Using a multivariate discriminant analysis, however, a combination of 7 criteria was identified, including hamster oocyte penetration and elements of both sperm movement and the semen profile, which could predict the fertility of these patients with 85.2% accuracy.

Penetration of sperm from teratospermic men into zona-free hamster eggs

The ability of sperm samples from male partners of infertile couples, with isolated teratospermia (ITS), to penetrate zona-free hamster eggs was examined. The ITS patients had a significantly lower proportion of normal spermatozoa than did a control group of men of proven fertility (23.6% and 47.8%, respectively; P less than 0.001), while the mean total sperm count and the % motility did not differ between the two groups. The mean hamster egg penetration rate of sperm from ITS patients was 2.64% compared to 31.1% in the control group. A significant negative correlation was found in the ITS group between the proportion of a) abnormal forms and the ability to penetrate zona-free hamster eggs, and b) pyriform-shaped sperm and the penetration rate. Of the sperm parameters which were examined, only the morphology could be correlated with the rate of penetration.

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

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

Effect of clomiphene citrate on human spermatozoal motility and fertilizing capacity in vitro

The effect of clomiphene citrate (CC) at various concentrations (0.005, 0.05, 0.5, 5, and 50 micrograms/ml) on the in vitro motility and fertilizing capacity of human spermatozoa was studied. Spermatozoa collected from 14 normal men were washed in modified Krebs-Ringer solution (Biggers, Whitten and Whittingham [BWW] medium) and incubated with CC for 5 hours, the period required for spermatozoal capacitation. The percent motilities of spermatozoa were recorded at 0 and 5 hours during incubation with CC. After incubation, the spermatozoa were washed with BWW medium to remove CC before insemination of the zona-free hamster ova. CC caused a significant dose-dependent decrease in the penetration of denuded hamster ova in comparison with the control (P less than 0.05). Significant depressive effect on spermatozoal motility was observed with CC at 0.05 micrograms/ml or higher concentrations (P less than 0.05). These results indicate that (1) CC decreases human spermatozoal fertilizing capacity in vitro and (2) the inhibitory effect on fertilizing capacity could be due to the sperm-immobilizing activity of CC.

Linear and nonlinear mouse sperm motility patterns. A quantitative classification

A quantitative method is described for distinguishing two types of mouse sperm motility using a new parameter, the Linear Index. One hundred spermatozoa from C57BL/6-+/+ and 100 spermatozoa from C57BL/6-tw32/ + mice were used to evaluate this parameter. Spermatozoa were tracked by videomicrography, and the following calculated: net displacement velocity, Vn; curvilinear velocity of the sperm head, Vc; the "average" velocity, Va (a 5-point moving average of the track); the progressiveness ratio, (Vn/Vc); the curvilinear progressiveness ratio, (Va/Vc); and a linear index, (Vn/Va). Frequency histograms of linear index values were bimodal for both groups and each had a clear antimode at 0.5, separating two discrete subpopulations of spermatozoa. Within each group, "linear" (greater than 0.5) and "nonlinear" (less than 0.5) tracks differed in all characteristics; between groups, linear spermatozoa were similar and nonlinear spermatozoa differed only in the curvilinear velocity of the sperm head.

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

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

A prospective study of the relationship between semen quality and fertility in cases of unexplained infertility

The male partners of 68 couples exhibiting 5.1 +/- 0.3 (SEM) years of unexplained infertility were assessed using the conventional criteria of semen quality, the movement characteristics of the spermatozoa and the outcome of the zona-free hamster egg penetration test. After a follow-up period of 2.3 +/- 0.06 (SEM) years, 25 (37%) of these patients were found to have initiated a pregnancy, thereby permitting an analysis of those aspects of semen quality which most accurately predicted their subsequent fertility. A multivariate discriminant analysis revealed that the conventional semen profile, per se, was not of significant value in discriminating the incidence of pregnancy. However, significant discrimination (P = 0.0173) was obtained when the postcapacitation movement characteristics of the spermatozoa were incorporated into the analysis. The accuracy of this prognosis was further increased if either the duration of infertility or the outcome of the zona-free hamster egg penetration test was taken into consideration. Overall classifications of fertility were then 76.3% and 76.5% accurate, respectively. These results suggest that in vitro assessments of human sperm function are of significant value in evaluating male fertility.

Analysis of human sperm function following exposure to the ionophore A23187. Comparison of normospermic and oligozoospermic men

Time exposure photomicrography and interspecific in vitro fertilization techniques have been used to compare the responses to the divalent cation ionophore A23187 of spermatozoa from normal fertile and oligozoospermic men. The fertilizing capacity of spermatozoa from the fertile controls produced a bell-shaped dose response curve when assessed in the presence of ionophore. The optimal responses occurred in the presence of 50 and 100 microM A23187. At this concentration, a mean penetration rate of about 75%, in association with multiple polyspermy, was observed without significant changes in motility patterns. At higher doses of A23187, there was a decline in fertilization rates, an independent reduction in sperm motility, and a significant decrease in the amplitude of lateral sperm head displacement. In contrast to the fertile controls, spermatozoa recovered from patients with oligozoospermia failed to exhibit a significant change in their fertilizing potential following exposure to A23187. Calculations based on the Poisson distribution theory indicated that this lack of responsiveness was not related to any differences in the motility of the spermatozoa from the oligozoospermic patients compared to the controls. These results suggest that calcium ionophores may be of value in providing a rapid and sensitive indicator of the functional competence of human spermatozoa, which circumvents problems concerning the rate and efficiency of sperm capacitation encountered with conventional protocols.

The prognosis of male subfertility: a survey of 1025 men referred to a fertility clinic

A retrospective survey of 1025 consecutive men referred to a male fertility clinic was carried out: 180 (18%) produced a pregnancy while attending the clinic. There was an overall inverse relationship between age and the production of pregnancy, although the majority of pregnancies were in the partners of men aged 25 to 39 at referral. The proportion of pregnancies rose from 4% for men presenting with azoospermia to 27% for those with initial sperm counts of 11 to 20 million/ml. The relationship between production of pregnancy and sperm density was inconsistent for men with sperm densities above 20 million/ml. There was no significant difference in the sperm motility at referral between those who did or did not produce a pregnancy. Success was highest for men whose duration of infertility at referral was between 2 and 3 years. The importance of these findings to the investigation of infertile men is discussed.

A regimen for obtaining mature human oocytes from donors for research into human fertilization in vitro

Patients awaiting laparoscopic sterilization were canvassed to allow oocytes to be aspirated from their ovaries at the time of operation for the purpose of testing the fertilizing capacity of spermatozoa from clinically infertile men. Because these patients were volunteers, the standard techniques for stimulation, ovulation prediction, operation, and oocyte recovery had to be modified for maximum safety and for convenience to both patient and staff. Superovulation was induced with 100 mg or 150 mg clomiphene citrate on days 2 to 6 or 5 to 9 of the menstrual cycle. Final maturation of oocytes was stimulated with 5000 IU of human chorionic gonadotropin administered between days 11 and 15 of the cycle, and the operation was performed 34 to 36 hours later on the routine gynecology operation lists. Of the 157 patients canvassed , 47% were willing to donate oocytes to the project. Despite the variability of the stimulation regimens, the simplified operative technique, and the fact that more than half the patients were on oral contraceptives in the previous cycle, one or more oocytes were retrieved in 75% of the patients. At the initial assessment, 83% of these were considered suitable for in vitro fertilization.

The role of cervical mucus--semen interaction in infertility of unknown aetiology

An in-vitro penetration assay, which incorporates measurements of sperm motility and forward velocity, was used to investigate sperm-cervical mucus interaction in 20 couples with unexplained infertility. Evidence of impaired cervical mucus penetration was found in this group of patients and in seven couples the results correlated with previous assessment by laparoscopic sperm recovery. The impairment of cervical mucus penetration was found to be due to defective sperm function rather than to the quality of the cervical mucus itself. Of the criteria of semen quality measured in this study, sperm motility and the zona-free hamster egg penetration test showed significant correlations with cervical mucus penetration.

Conditions influencing human sperm capacitation and penetration of zona-free hamster ova

The ability of human spermatozoa to penetrate zona-free hamster ova was examined following low-temperature capacitation (4 degrees C) in TES-Tris (TEST)-yolk buffer for periods of up to 66 hours. Results obtained from 66 individuals demonstrated that the number of penetrations per ova were increased by an average of 2.5-fold when spermatozoa were capacitated for 42 hours, as compared with 18 hours. Furthermore sperm with extremely poor penetration rates after 18-hour capacitation was often improved by longer capacitation periods. Patients from our infertility clinic with less than 20 X 10(6) spermatozoa/ml of ejaculate had significantly lower penetration rates when compared with patients and donors with greater than 20 X 10(6) spermatozoa/ml (P less than or equal to 0.001). The observed effects of TEST-yolk buffer appear to be related to its ability to preserve sperm motility over prolonged periods, during which increased capacitation of the total sperm population is achieved.