Kruger strict morphology and post-thaw progressive motility in cryopreserved human spermatozoa

The purpose of this prospective study was to evaluate Kruger strict morphology and conventional semen analysis in predicting cryosurvival and the progressive motility recovery rate of frozen spermatozoa. Our study included 56 semen samples with >10 million spermatozoa per ejaculate. The main outcome measures were conventional semen analysis, strict morphology analysis by the Kruger method, cryosurvival rate and post-thaw sperm motility. A significant reduction in sperm motility after cryopreservation was demonstrated. The freeze-thawing process caused a 66% reduction in rapid progressive motile spermatozoa, a 45% reduction in slow progressive motile spermatozoa and a 2% reduction in nonprogressive motile spermatozoa. The cryosurvival and progressive motility recovery rates were not correlated with parameters of conventional semen analysis, such as sperm concentration, motility, WHO morphology and total motile count, but the progressive motility recovery rate was significantly correlated with the percentage of spermatozoa exhibiting Kruger normal morphology (P = 0.028). The recovery rate of rapidly progressive motility was profoundly decreased compared with slow progressive motility following the frozen-thaw procedure of semen. Kruger strict morphology assessment was a better predictor of the progressive motility recovery rate following the freezing-thaw procedure than parameters of conventional semen analysis.     

Semen quality changes among 2343 healthy Slovenian men included in an IVF-ET programme from 1983 to 1996

To determine whether semen quality in Slovenians has changed over 14 years (1983-96), we analysed retrospectively the semen of 2343 healthy men with a normal spermiogram, who were partners of women with tubal infertility included in the IVF-ET programme. Age at semen collection, duration of sexual abstinence, semen volume, sperm concentration, total sperm count, percentage of spermatozoa with progressive motility, and normal morphology were determined. Multiple regression analysis was used to assess the changes in sperm characteristics according to the year of semen collection, year of the man's birth and the duration of sexual abstinence. Semen volume, sperm concentration, sperm count and total sperm motility did not change between 1983 and 1996, whereas between 1988 and 1996 rapid progressive sperm motility decreased by 0.95% per year (p < 0.0001). Semen volume, sperm concentration, and sperm count increased with duration of sexual abstinence. After adjustment for the year of semen collection and duration of sexual abstinence, multiple regression analysis showed that sperm concentration decreased by 0.67% per each successive year of birth (p = 0.03). Thus the sperm concentration decreased from 87.6 x 10(6)/mL in men born in the 1940s to 77.3 x 10(6)/mL in those born between 1956 and 1960. After 1960, sperm concentration was found to increase. In 2343 healthy men, no decline in semen quality, except in rapid progressive motility, was observed in the study period. Lower sperm concentration was found among men born between 1950 and 1960. This could be related to worse socio-economic status, stress or negative environmental factors in this time period.     

捐精者精子冷冻复苏率影响因素分析

目的:探讨季节、血型及精液参数等对捐精者精子冷冻复苏率的影响。方法:回顾性分析陕西省人类精子库捐精者4 088份精液标本,研究季节、血型、禁欲时间、精液量、精子形态、冷冻前精子活力及浓度对精子冷冻复苏率的影响。结果:捐精者精子冷冻复苏率随着精子浓度增高而增加,相关性分析提示精子浓度与冷冻复苏率呈正相关(r=0.247,P0.01)。而精子冷冻前活力和精子冷冻复苏率呈负相关(r=-0.262,P0.01)。禁欲第6天组的精子冷冻复苏率[(70.2±5.4)%]明显高于其他禁欲时间组(P0.01)。精子正常形态率20%组的精子冷冻复苏率[(71.4±5.1)%]要高于其他各组(P0.01)。A型血精子冷冻复苏率明显高于B型血[(69.1±4.8)%vs(69.8±4.7)%,P0.01];季节、精液量与精子冷冻复苏率之间无明显相关性(P0.05)。结论:捐精者的精子浓度、活力、形态及禁欲时间对于预测精子冷冻复苏率有一定的价值,而季节、血型、精液量与捐精者精子冷冻复苏率无明显相关性。     

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.     

Decline of semen quality among 10 932 males consulting for couple infertility over a 20-year period in Marseille,France

Semen from 10 932 male partners of infertile couples was analysed and sperm parameter trends were evaluated at the Reproduction Biology Laboratory of the University Hospital of Marseille (France) between 1988 and 2007. After 3–6 days of abstinence, semen samples were collected. Measurements of seminal fluid volume, pH, sperm concentration, total sperm count, motility and detailed morphology of spermatozoa were performed. Sperm parameters were analysed on the entire population and in men with normal total numeration (≥40 million per ejaculate). The whole population demonstrated declining trends in sperm concentration (1.5% per year), total sperm count (1.6% per year), total motility (0.4% per year), rapid motility (5.5% per year) and normal morphology (2.2% per year). In the group of selected samples with total normal sperm count, the same trends of sperm quality deterioration with time were observed. Our results clearly indicate that the quality of semen decreased in this population over the study period.     

Relationship between morphology and motion characteristics of human spermatozoa in semen and in the swim-up sperm fractions

In this study, the authors evaluated the morphology pattern and motion characteristics of human spermatozoa before and after swim-up separation. Samples were divided into two, morphologically different groups according to the percentage of normal sperm forms assessed by the strict criteria of the Norfolk laboratory: "good"(G) and "poor" (P) prognosis patterns. The percentages of normal forms, slightly abnormal forms, and severe head defects were significantly different in the two groups. Motile characteristics were analyzed by a computerized semen analyzer with constant parameter settings. Before swim-up there were no significant differences in semen volume, percentage of neck and tail defects, concentration, or percentage of motility and linearity, but the mean velocity was higher in group G. After swim-up the percentage of motility, total number of motile cells, and recovery rate were higher for group G, and the incidence of severe head defects correlated negatively with the percentage of cells with a velocity of greater than 80 microns/sec. The results suggest that patients with a high incidence of sperm head defects have impaired original velocity, and swim-up selects for velocity as well as normal forms and motility. Although motility and velocity improved substantially after swim-up, the recovery rate and percentage of motility were significantly lower in the P group.     

男性年龄与精子顶体酶活性及精子DNA碎片指数的相关性分析

目的探讨男性年龄与精子顶体酶活性、精子DNA碎片指数(DFI)的相关性。方法选取2016年1~8月在我院生殖医学中心就诊的436例不育症男性患者为研究对象,所有患者均行精液常规检查、精子顶体酶活性检查和(或)精子DFI分析。将患者按年龄分为<30岁、30~39岁、≥40岁3组,分析各组的精液常规、顶体酶活性及精子核DFI的差异及其相关性。结果不同年龄段患者的体重指数(BMI)、禁欲天数、精液量无显著性差异(P>0.05);年龄≥40岁组患者的前向运动精子百分率、活动精子百分率及精子顶体酶活性显著低于<30岁和30~39岁组(P<0.05);≥40岁组患者的精子DFI显著高于<30岁和30~39岁组(P<0.05)。年龄与前向运动精子百分率及活动精子百分率之间呈负相关(P<0.05),但是相关性较弱。精子顶体酶活性与精子正常形态率、前向运动精子百分率、非前向运动精子百分率、活动精子百分率呈正相关(P<0.05);精子DFI与年龄、禁欲天数、前向运动精子百分率呈正相关(P<0.01),与精液量、精子浓度、活动精子百分率呈负相关(P<0.05);精子顶体酶活性和DFI之间无相关性(P>0.05)。结论年龄增长会导致精液前向运动精子百分率、活动精子百分率、精子顶体酶活性、DFI等参数改变,直接或间接影响男性生育力。说明年龄对男性不育的影响是多方面的,建议有生育需求的大龄(≥40岁)男性尽早进行生育咨询与评估。     

Advanced methods for evaluation of sperm quality

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

Direct effect of alcohol on the motility and morphology of human spermatozoa

Excessive alcohol consumption has been associated with impaired reproductive function by causing the inhibition of penile tumescence and ejaculatory capability. Alcohol intoxication has also been implicated in impaired spermatogenesis and an increase in sperm structural anomalies. The aim of this study was to determine the direct effects of alcohol on sperm motility and morphology in vitro.
Semen samples from 67 subjects were prepared using density centrifugation. Ethanol was added, at concentrations in serum equivalent to social, moderate and heavy drinking, to the medium in which the spermatozoa were cultured. Sperm motility was assessed using computer assisted semen analysis and morphology was assessed by Tygerberg strict criteria after 0, 15, 30, 60, 120, 180 and 240  min exposure. Each concentration of ethanol produced significant decreases in the percentage progressive motility, straight line velocity and curvilinear velocity. The amplitude of lateral head displacement was also depressed by 300 and 500  mg  dL⁻¹ of ethanol. A significant decrease in the number of spermatozoa with normal morphology and an increase in irreversible tail defects were observed after exposure to 300  mg  dL⁻¹ ethanol.
When alcohol is added directly to sperm, at concentrations equivalent to those in serum after moderate and heavy drinking, damaging effects are observed in both sperm motility and morphology.     

Predictive value of CASA parameters in IUI with frozen donor sperm

The objective of this study was to determine if characteristics of sperm motion determined by computer-aided semen analysis (CASA) after thawing and preparation on discontinuous gradient could predict pregnancy outcome after intrauterine insemination (IUI) from frozen donor sperm. A retrospective analysis of 100 non-selected women undergoing 171 consecutive donor insemination cycles was conducted between January 2006 and April 2007. Semen samples from all donors were analysed after thawing and density gradient preparation. Women who became pregnant and those who did not were comparable in terms of age, ovarian stimulation regimen and indication of IUI with donor semen. Pregnancy rate per cycle was 21.8%, and pregnancy occurred after 2.5 IUI cycles on average. Motility parameters of sperm measured by CASA (VAP, VCL, VSL, LIN, STR, and ALH) and total spermatozoa concentration after preparation on discontinuous gradient showed no difference in both groups. Progressive and total motile spermatozoa concentration, as well as progressive and total motile percentages was significantly higher in pregnancy group. The receiver operating characteristic (ROC) curve analysis showed that total motile percentage >17% and motile concentration >0.9 × 10⁶/mL best predicted pregnancy. In a multivariate analysis, only total motility percentage was able to predict pregnancy. Sperm motility parameters of frozen-thawed prepared donor sperm obtained by CASA do not seem to predict pregnancy in IUI cycles. Total motile and progressive percentages and concentrations remain the best prognostic elements for pregnancy in IUI with donor semen.     

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.     

速冻和缓慢冷冻法对精子运动特征的影响

目的了解冷冻方法对人精子运动特征的影响。方法精液标本进行速冻和缓慢冷冻保存,应用计算机精液分析仪进行精子运动特征分析。结果冷冻复温后精子运动能力与冷冻前精子运动能力比较明显下降(P<0.001,P<0.05);速冻与缓慢冷冻方法保存的精子运动参数相比较差异均无显著性(P>0.05)。结论冷冻保存易导致精子运动能力下降,速冻与缓慢冷冻方法对精子运动参数影响无明显差异。     

Semen parameters in Norwegian fertile men

The World Health Organization (WHO) provides guidelines for assessing the various semen variables. A set of reference ranges is given in the WHO Laboratory Manual for the Examination of Human Semen and Sperm-Cervical Mucus Interaction, but several studies indicate that the values should be revised. Furthermore, semen parameters obtained at different laboratories are not directly comparable even if the same methods are used. Thus, it is recommended that each laboratory establish its own reference ranges. In this study, semen from 99 men who had recently achieved a pregnancy were analyzed to establish reference ranges for semen variables. The reference values were based on the group with time to pregnancy (TTP) 12 cycles or less (92%) and abstinence time from 2 to 7 days. The 5th and 10th percentiles for sperm concentration were 10.6 and 16.9 x 10(6)/mL, respectively, and 33% (5th percentile) and 43% (10th percentile) for spermatozoa with progressive motility. These values were below the WHO lower limit. The percentages of ideal spermatozoa (percentage with normal morphology according to WHO strict criteria) were 3 (5th percentile) and 4 (10th percentile). Thirty-nine percent reported that their partners became pregnant during the first cycle after they had stopped using contraception. The semen parameters in this group were compared with the others. Overall, the semen parameters were more favorable in the group with TTP = 1 cycle than in the group with TTP > 1. Sperm concentration, progressive motility, and percentage of ideal spermatozoa according to WHO strict criteria were significantly different in the 2 groups. However, when analyzed by multiple logistic regression, only "total numbers of sperm with progressive motility" remained in the model (P = .002). This is in accordance with previous studies indicating that a combination of semen characteristics provides a better predictor of male fertility potential than the single parameters. In conclusion, new reference ranges for semen variables deviating from the WHO values are established for our laboratory.     

Quality assessment of frozen bull semen with the precursor A-kinase anchor protein 4 biomarker

In this study, the quality of frozen bull semen was evaluated with the proAKAP4 level test. Sixty straws of frozen bull semen from various batches (n = 30) belonging to six bulls were used in the current study. The frozen bull semen samples were analysed in terms of proAKAP4 levels, sperm morphology and sperm movement parameters at hour 0 and hour 3 after thawing. The semen samples were divided into three groups according to the proAKAP4 levels: low concentration (<25 ng/10x10⁶ spermatozoa), moderate concentration (25 to 39 ng/10x10⁶ spermatozoa) and high concentration (≥40 ng/10x10⁶ spermatozoa). A positive correlation was found between the proAKAP4 level and total motility (TM₃), progressive motility (PM₃), VSL₃ and VCL₃ values obtained after the third-hour thermoresistance test (p < .05). There was a negative correlation between the percentage of sperm abnormal tail and the proAKAP4 level (p < .01). In addition, it was observed that the semen samples with proAKAP4 concentrations of 25 ng/10⁶ spermatozoa and higher preserved the TM₃ and PM₃ motility characteristics. In conclusion, the proAKAP4 has the potential to become a biomarker protein to evaluate in the quality analysis of frozen-thawed semen.     

Semen quality in adult male survivors 5 years after the 2008 Wenchuan earthquake

The influence of the Wenchuan earthquake on semen quality of adult male survivors is unclear. We investigated the semen quality included 673 male survivors from the worse‐affected counties in the earthquake between Aug 2008 and July 2013. Semen parameters including pH, volume, concentration, motility and morphology were measured according to the World Health Organization (WHO) criteria. Kruskal–Wallis analysis of variance was used to examine the statistical differences between years, and a logistic regression was used to analyse the impacts caused by earthquake on the changes of semen quality. We found the medians (5th and 95th) were 2.5 ml (0.6–5.5) for semen volume, 59.0 × 10⁶ ml^?1 [(13.0–133.0)] × 10⁶ ml^?1 for semen concentration, 46% (13–64%) for sperm progressive motility and 3.0% (0–17.5%) for normal morphology for adult male survivors. Semen concentration, the percentage of sperm progressive motility, total motility and sperm normal morphology were all decreased in the first 3 years, and the differences among years 1, 2 and 3 were significant except the percentage of sperm progressive motility (P < 0.05). The casualties and heavy housing damage caused by earthquake had a negative effect on semen quality. The main findings will provide further diagnosis and therapy basis of male fertility by data, for affected populations in the earthquake.     

Effect of age on quality of fresh and frozen－thawed semen in White Italian gandersin White Italian ganders

AIM: To comparatively evaluate the fresh semen quality of 1, 2 and 3-yr-old White Italian ganders (Anser anser L.) and the susceptibility of spermatozoa to freezing-thawing procedure. METHODS: Semen was collected by dorso-abdominal massage every 2 days~3 days from three groups of ganders: 1-yr-old (n=11), 2-yr-old (n=7) and 3-yr-old (n=9). In the pooled fresh semen samples, the following parameters were evaluated: the ejaculate volume, the blood or feca contamination and the motility, concentration and morphology of spermatozoa. Sperm motility and morphology were evaluated in the frozen-thawed semen. Semen diluted with EK extender was frozen in straws in a computerized freezing unit with 6 % dimethyl-formamide to -140 deg at a rate 60 deg/min and then transferred into the LN2 container. Straws with semen were thawed in a water bath at 60 deg. RESULTS: The ejaculate volume decreased with the age (0.21 mL for 1-yr-old, 0.18 mL for 2-yr-old and 0.14 mL for 3-yr-old ganders); the sperm concentration increased with the age (327 x 10(6) mL(-1) for 1-yr-old, 431 x 10(6) mL(-1) for 2-yr-old and 547x10(6) mL(-1) for 3-yr-old ganders); the number of live - normal sperm was significantly (P<0.01) lower in the 1-yr-old than that in the 2- and 3-yr-old ganders (26.61 %, 41.54 and 35.9 %, respectively). The percentage of normal cells survived the freezing-thawing process was 37.7 %, 43.3 % and 40.9 % for 1-, 2- and 3-yr-old ganders, respectively. CONCLUSION: Freezing and thawing processes more significantly (P<0.01) affected the motility, viability and morphology of spermatozoa in semen of 1-yr-old ganders in comparison with older males.     

The association of seminal leucocytes,interleukin‐6 and interleukin‐8 with sperm DNA fragmentation: A prospective study

The effect of seminal leucocytes on sperm DNA integrity has been discussed controversially in literatures. Moreover, the studies investigating the in vivo effect of pro‐inflammatory cytokines interleukin‐6 and interleukin‐8 on sperm DNA fragmentation are scarce and inconsistent. The association of standard sperm parameters with sperm DNA fragmentation is also a matter of ongoing discussion. Hence, the aims of this study were, first, to evaluate the effect of seminal leucocytes, interleukin‐6 and interleukin‐8 on sperm DNA integrity and, second, to examine whether standard semen parameters are associated with sperm DNA fragmentation. Seminal leucocytes, interleukin‐6, interleukin‐8 and standard semen parameters, including total sperm number, sperm concentration, progressive motility, nonprogressive motility, immotility and normal morphology, were determined in 134 consecutive men. The concentrations of seminal leucocytes, interleukin‐6 and interleukin‐8, did not correlate with sperm DNA fragmentation. In contrast, total sperm number, sperm concentration, progressive motility, nonprogressive motility and normal morphology exhibited significant inverse correlations with sperm DNA fragmentation. Immotile spermatozoa were directly correlated with sperm DNA fragmentation. In conclusion, seminal leucocytes, interleukin‐6 and interleukin‐8, are not associated with sperm DNA fragmentation. Poor standard semen parameters are significantly related to the high levels of sperm DNA fragmentation.     

用传统方法与计算机辅助精液分析软件CRISMAS分析166名丹麦青年男性精液样本的结果比较

本研究以166名丹麦青年男性精液为样本,通过评估精于浓度和活力来比较传统精液分析与计算机辅助精液分析方法（CASA）（哥本哈根Rigshospitalet图像屋精子运动分析系统,CRISMAS软件4．6版本）。CRISMAS软件测定精子的浓度把精子活力分为三类。传统分析方法将精子活力分为四种状态。为了便于二者的比较,本文将传统的四种状态根据精子速度等级重新分为三个状态：rapidly progressive（A）,slowly progressive（B）和non-progressive（C＋D）。两种方法所研究的参数之间都有显著差异（P〈0．001）。与传统方法相比,CRISMAS高估了精子浓度以及快速运动精子的比例,因而低估了慢速运动和非运动精子。为分析研究结果是否会随精液分析时间而起伏变动,将精液分析结果按分析同期分为四个层次。结果表明CRISMAS对活力的分析结果比传统分析方法稳定,但两种方法都未表现出任何趋势。显然,无法比较CRISMAS CASA和传统分析方法在精子浓度和精子活力方面的分析结果。在临床上使用该软件时以及用其研究这些精子特性时需要说明这一点。     

Effects of clinical stage and immunological status on semen analysis results in human immunodeficiency virus type 1-seropositive men

Summary. Complete semen analyses including computer-assisted sperm motility and morphology assessments were performed to determine if semen and sperm differed between HIV-seropositive men and fertile controls, or differed with symptoms, or CD4+ peripheral cell count categories. Previous studies included small numbers of men and presented conflicting conclusions. Two hundred and fifty non-vasectomized HIV-seropositive men and 38 fertile controls each provided one semen sample. Non-parametric statistics were used to analyse both continuous and nominal data. Fertile men had significantly greater semen volume, sperm concentration, percent motility, percent rapid and linear motility and total strictly normal spermatozoa than HIV seropositive men. Neither total number nor subtypes of leukocytes in semen differed between the two groups. Among the HIV seropositive men, significant differences in semen analyses were found between CD4+ cell count, clinical, and AIDS categories. Lower CD4+ cell counts (<200 mm⁻³) were associated with significantly lower percent motility, percent normal sperm morphology by strict criteria, significantly more spermatids in semen, and higher percentages of teratozoospermia, oligoasthenoteratozoospermia and leukocytospermia. Healthier men, based on clinical categories, had significantly more normal shaped spermatozoa and fewer had azoospermia, oligoasthenoteratozoospermia or leukocytospermia. Many HIV-seropositive men have normal semen analyses, but as the disease progresses more defects are found, particularly in strict criteria sperm morphology.     

Evaluation of sperm fertilizing ability using the Sperm Quality Analyzer

The Sperm Quality Analyzer is an inexpensive device which provides a quantitative estimation of sperm motility. To evaluate the fertilizing ability of human spermatozoa using a Sperm Quality Analyzer, correlations amongst the sperm motility index, the sperm penetration index (as assessed using the sperm penetration assay; SPA), and the fertilization rate in the treatment of standard IVF-ET were analysed retrospectively. The sperm motility index demonstrated a significant correlation with sperm concentration ( p  < 0.001), sperm motility ( p  < 0.001) and the motile sperm concentration ( p  < 0.001) in a total of 104 fresh semen samples from 81 men donating samples for IVF-ET. The sperm motility index also showed a significant correlation ( p  < 0.001) with the sperm penetration index in 60 patients, assessed using the SPA, before they were treated by standard IVF-ET. The correlation between the sperm motility index and the IVF-ET fertilization rate was higher than that between the sperm penetration index and the fertilization rate. The sperm motility index was classified into three categories: `poor' (sperm motility index < 80), `medium' (sperm motility index 81–160) and `good' (sperm motility index>  160). The relationships between the IVF-ET fertilization rate and each category of the sperm motility index values were also evaluated. For the three categories in the sperm motility index, the fertilization rates (76.0%) of 60 samples judged as `good' were significantly higher than those (44.2%) of 15 samples judged as `medium' ( p  < 0.001) and those (34.7%) of 13 samples judged as `poor' ( p  < 0.001). These results indicate that the Sperm Quality Analyzer provides a reliable estimation of the fertilizing ability of human spermatozoa.