Semen analysis and sperm function testing

Despite controversy regarding the clinical value of semen analysis, male fertility investigation still relies on a standardized analysis of the semen parameters. This is especially true for infertility clinics in both developing and developed countries. Other optional tests or sophisticated technologies have not been widely applied. The current review addresses important changes in the analysis of semen as described in the new World Health Organization （WHO） manual for semen analysis. The most important change in the manual is the use of evidence-based publications as references to determine cutoff values for normality. Apart from the above mentioned changes, the initial evaluation and handling methods remain, in most instances, the same as in previous editions. Furthermore, the review evaluates the importance of quality control in andrology with emphasis on the evaluation of sperm morphology. WHO sperm morphology training programmes for Sub-Saharan countries were initiated at Tygerberg Hospital in 1995. The external qualitY control programme has ensured that the majority of participants have maintained their morphological reading skills acquired during initial training. This review reports on current sperm functional tests, such as the induced acrosome reaction, and sperm-zona pellucida binding assays, as well as the impact of sperm quality in terms of DNA integrity, and the relationship of sperm function tests to sperm morphology.

Tests to measure the quality of spermatozoa at spermiation

This commentary is to critique the revised World Health Organization （WHO） semen analysis manual as it pertains to characteristics of a spermatozoon at spermiation. The aims of the revised WHO manual include improving the ＇quality of semen analysis＇ without any restriction to clinical use. Furthermore, the manual states that semen analysis may be useful for （a） ＇investigating male fertility status＇ and （b） ＇monitoring spermatogenesis during and following male fertility regula- tion.＇ However, if the analysis of ejaculated spermatozoa is intended for the purposes described in （b）, then cells that are abnormal at spermiation must be identified. This paper takes the position that the manual does not identify methods to estimate the quality of spermatozoa at spermiation. Instead, it uses a ＇gold standard＇ of sperm passing through the cervical mucus or arriving near the site of fertilization. Although this standard is appropriate for drawing conclusions regarding the probability that an individual could impregnate his partner, it is not appropriate for studying illness of the testes per se. Herein, the measures of sperm quality presented in the WHO manual are critiqued with respect to the detection of spermatozoa that were abnormal at spermiation vs. those that became abnormal subsequently. Quality assessments based on the percentage of motile or ＇viable＇ spermatozoa are meaningless. Alternative quality attributes defining spermatozoa at spermiation are presented in this paper. In conclusion, assessment of spermatozoal quality at spermiation, on the basis of quality attributes of individual ejaculated spermatozoa, is best achieved through application of （a） a new paradigm for the morphological evaluation of sperm quality and （b） modern analytical techniques to evaluate, in an adequate sample, several appropriate independent attributes in each spermatozoon in order to more accurately identify the proportion of abnormal spermatozoa.

A comparison of conventional and computer-assisted semen analysis.（CRISMAS software） using samples from 166 young Danish men

The aim of the present study was to compare assessments of sperm concentration and sperm motility analysed by conventional semen analysis with those obtained by computer-assisted semen analysis （CASA） （Copenhagen Rigshospitalet Image House Sperm Motility Analysis System （CRISMAS） 4.6 software） using semen samples from 166 young Danish men. The CRISMAS software identifies sperm concentration and classifies spermatozoa into three motility categories. To enable comparison of the two methods, the four motility stages obtained by conventional semen analysis were, based on their velocity classifications, divided into three stages, comparable to the three CRISMAS motility categories： rapidly progressive （A）, slowly progressive （B） and non-progressive （C＋ D）. Differences between the two methods were large for all investigated parameters （P〈0.001）. CRISMAS overestimated sperm concentration and the proportion of rapidly progressive spermatozoa and, consequently, underestimated the percentages of slowly progressive and non-progressive spermatozoa, compared to the conventional method. To investigate whether results drifted according to time of semen analysis, results were pooled into quarters according to date of semen analysis. CRISMAS motility results appeared more stable over time compared to the conventional analysis; however, neither method showed any trends. Apparently, CRISMAS CASA results and results from the conventional method were not comparable with respect to sperm concentration and motility analysis. This needs to be accounted for in clinics using this software and in studies of determinants of these semen characteristics.

Sperm Quality and Environment: A Retrospective, Cohort Study among 21,715 Semen Samples in a Southern Province of China

To explore the differences of male semen parameters in different seasons of the year, so as to explore the potential climatic factors affecting spermatogenesis and male reproductive ability, we retrospectively analyzed 21,715 semen analysis data from January 2018 to February 2021, grouped by year and season, and finally the relationships among semen parameters and semen and meteorological parameters were compared. Environmental exposures prior to 3 months were analyzed and correlation analysis was performed.The semen concentration decreased year by year (p < 0.01). However, the Progressive motility (PR) and total PR number had been increased (p < 0.01). There were statistical differences in sperm parameters which include semen volume, sperm concentration, total sperm number, progressive motility (PR), total PR number and total motility in different seasons, winter and spring were better than summer and autumn (p < 0.01). Total sperm number and sperm concentration were positively correlated with PR (R = 0.420, R = 0.440, p < 0.01). There was no correlation between daylight duration and semen parameters. Sperm parameters were positively or negatively correlated with environmental temperature, air pressure or humidity which had an overall effect on semen quality. It is suggested that seasonal factors should be considered when evaluating male reproductive ability. Besides referring to conventional semen parameters, other factors such as season and climate should also be considered.

The usefulness and significance of assessing rapidly progressive spermatozoa

It is possible and clinically relevant to distinguish between slow and rapid progressive spermatozoa in basic semen analysis. This is discussed in light of the different purposes of semen analysis for the subfertile couple and the male patient. The two groups of progressive spermatozoa should be distinguished to help ensure that pertinent information available in the semen sample is not neglected.

The impact of male overweight on semen quality and outcome of assisted reproduction

It is well-documented that male overweight and obesity causes endocrine disorders that might diminish the male reproductive capacity; however, reports have been conflicting regarding the influence of male body mass index （BMI） on semen quality and the outcome of assisted reproductive technology （ART）. The aim of this study was to investigate whether increased male BMI affects sperm quality and the outcome of assisted reproduction in couples with an overweight or obese man and a non-obese partner. Data was prospectively collected from 612 infertile couples undergoing ART at a Danish fertility center. Self-reported information on paternal height and weight were recorded and BMI was calculated. The men were divided into four BMI categories： underweight BMI 〈 20 kgm^-2, normal BMI 20-24.9 kg m^-2, overweight BMI 25-29.9 kgm^-2 and obese BMI 〉 30 kgm^-2. Conventional semen analysis was performed according to the World Health Organization guideline and sperm DNA integrity was analyzed by the Sperm Chromatin Structure Assay （SCSA）. No statistically significant effect of male BMI was seen on conventional semen parameters （sperm concentration, total sperm count, seminal volume and motility） or on SCSA-results. Furthermore, the outcome of ART regarding fertilization rate, number of good quality embryos （GQE）, implantation and pregnancy outcome was not influenced by the increasing male BMIo

Influence of several uropathogenic microorganisms on human sperm motility parameters in vitro

Aim: The effects of certain uropathogenic microorganisms (Neisseria gonorrhoeae, Staphylococcus aureus, Staphylococcus epidermidis and Mycobacterium tuberculosis) on human sperm motility characteristics were studied in vitro. Methods: In 10 healthy fertile men, ejaculates were aseptically obtained by masturbation and With a swim-up technique, a sperm suspension of high motility and purity was obtained. Several uropathogenic bacteria were obtained from outpatients with genitourinary tract infections. The sperm suspension was incubated with the pathogens at a bacteria: sperm ratio of 50:1 at 37℃. The sperm mobility parameters were estimated with a computerassisted sperm analyzer (CASA) provided with a multiple-exposure photography system (Madi Corp., Zhejiang, China). Measurements were carried out at 0, 2 and 4 hours of incubation. Results: Staphylococcus aureus significantly decreased the sperm motility and viability, but Staphylococcus epidermidis, Mycobacterium tuberculosis and Neisseria gonorrhoeae did not. Conclusion: Staphylococcus aureus has an inhibitory effect on human sperm motility in vitro.

Sperm speed is associated with sex bias of siblings in a human population

Recent studies investigating possible causes of male subfertility have largely focused on how lifestyle or environmental factors impact on the process of spermatogenesis, Markedly, fewer studies have investigated those risk factors that result in reduced sperm quality, such as poor sperm motility. The speed at which sperm swim is a major predictor of fertility and is extremely variable in human populations. It has been hypothesized that offspring sex may be adaptively manipulated to maximize the offspring＇s reproductive fitness （e.g., parents with genes for good male fertility traits, such as high sperm speed, would produce primarily sons and fewer daughters because the offspring will inherit advantageous male fertility genes）. Conversely, parents with poor male fertility genes would produce primarily daughters, We tested whether there was an association between how fast a man＇s sperm swam and the sex bias of his siblings in a sample of men attending clinic for fertility investigations with their partner and with a wide range of semen characteristics, including sperm speed. We found that the sex bias of a man＇s siblings is associated with his sperm speed; men with female-biased siblings had significantly slower sperm （judged using computer-assisted sperm analysis （CASA）） than men from male-biased sibships. This observation suggests family composition is an important factor that needs to be considered in future eDidemiological and clinical studies of human fertility,

Computer-assisted sperm morphometry fluorescence-based analysis has potential to determine progeny sex

This study was designed to determine the ability of computer-assisted sperm morphometry analysis （CASA-Morph） with fluorescence to discriminate between spermatozoa carrying different sex chromosomes from the nuclear morphometrics generated and different statistical procedures in the bovine species. The study was divided into two experiments. The first was to study the morphometric differences between X- and Y-chromosome-bearing spermatozoa （SX and SY, respectively）. Spermatozoa from eight bulls were processed to assess simultaneously the sex chromosome by FISH and sperm morphometry by fluorescence-based CASA-Morph. SX cells were larger than SY cells on average （P 〈 0.001） although with important differences between bulls. A simultaneous evaluation of all the measured features by discriminant analysis revealed that nuclear area and average fluorescence intensity were the variables selected by stepwise discriminant function analysis as the best discriminators between SX and SY. In the second experiment, the sperm nuclear morphometric results from CASA-Morph in nonsexed （mixed SX and SY） and sexed （SX） semen samples from four bulls were compared. FISH allowed a successful classification of spermatozoa according to their sex chromosome content. X-sexed spermatozoa displayed a larger size and fluorescence intensity than nonsexed spermatozoa （P 〈 0.05）. We conclude that the CASA-Morph fluorescence-based method has the potential to find differences between X- and Y-chromosome-bearing spermatozoa in bovine species although more studies are needed to increase the precision of sex determination by this technique.

深度学习在辅助生殖技术领域的应用进展

深度学习是人工智能领域一种机器学习方法,它模拟人类大脑神经网络的工作原理来解决复杂的问题,目前在医学领域已有许多重要的研究和应用,如影像诊断、生物医学数据处理、药物研发、个性化医疗等,提高了医疗诊断和治疗的准确性及效率。在辅助生殖领域,深度学习在干预过程中高效识别生长良好的胚胎、适宜的卵母细胞或精子,协助专业人员做出更为准确的选择,提高妊娠率,减少多胎妊娠风险。本文将综合归纳近5年深度学习在辅助生殖技术领域的最新应用进展,并对今后研究方向进行展望。

精子核DNA完整性测定方案的优化及其在辅助生殖技术中的应用价值

目的:对现有精子核DNA完整性测定方案进行优化,并探讨其在辅助生殖技术(ART)中的应用价值。方法:选择2021年1月1日至2022年12月8日于江西中医药大学附属生殖医院就诊的拟接受体外受精-胚胎移植(IVF-ET)助孕的194对夫妇作为研究对象。采集男方的精液作为对照组(n=194),同一精液经双层密度梯度离心法优化处理后精子混合液作为观察组(n=194)。根据精子核DNA碎片率(DFI)测定结果将对照组及观察组各分为3个亚组,对照A组和观察A组:DFI<15%,对照B组和观察B组:DFI 15%~30%,对照C组和观察C组:DFI≥30%。对观察组与对照组的DFI值及各亚组间的助孕及妊娠情况进行比较。结果:(1)观察组DFI明显低于对照组,差异有统计学意义[(13.55±10.17)%vs.(18.56±11.54)%,P<0.05]。(2)6个亚组间的受精率、卵裂率及优胚率两两比较,差异无统计学意义(P>0.05)。(3)6个亚组的妊娠率和着床率比较,差异有统计学意义(P<0.05);其中,对照A组、对照B组、观察A组、观察B组4组的临床妊娠率(均在65.00%以上)及着床率(均在50.00%)两两比较,差异均无统计学意义(P>0.05),但均高于对照C组(43.24%、31.67%)及观察C组(13.64%、8.82%),差异有统计学意义(P<0.05);对照C组的临床妊娠率及着床率明显高于观察C组,差异有统计学意义(P<0.05)。结论:精液经优化处理后精子核DNA完整性可明显改善。两种不同检测方案在ART中均有较好的应用价值,当精液经优化处理后DFI≥30%时,对ART的不良妊娠结局具有更好的预测价值。

计算机辅助精子分析用精液样本的稀释条件及标准化研究

目的探讨计算机辅助精子分析(CASA)系统检测高浓度精液样本的稀释条件及标准。方法当精子浓度<50×10^(6)/mL时不稀释;当≥50×10^(6)/mL时,按1:[n/(50×10^(6))]的比例[n为精子浓度,n/(50×10^(6))向下取整]用生理盐水稀释至50×10^(6)/mL以下。采用CASA系统和10μm深度一次性计数板检测精液样本,分为未稀释组(组1:精子浓度<50×10^(6)/mL).50×10^(6)/mL≤精子浓度<100×10^(6)/mL组(组2)、精子浓度≥100×10^(6)/mL组(组3),稀释前后分析各组精子浓度、前向运动精子百分率(PR)、非前向运动精子百分率(NP)精子活动率(PR+NP)和不活动精子百分率(IM)等,比较稀释前后结果的一致性。采用ROC曲线预测最佳稀释阈值。结果随着精子浓度的增加,稀释前后各参数差异逐渐增大。ROC曲线分析结果显示,分别用精子浓度、PR+NP、PR、NP、IM預測时,精液标本的最佳稀释阈值分别为133.05×10^(6)/mL.101.75×10^(6)/ml.118.60×10^(6)/mL.90.90×10^(6)/m111.83×10^(6)/mL.结合高浓度精液样本未稀释检测时对精子浓度和NP的影响最大,确定最佳稀释固值为125.08×10^(6)/ml。结论建议当精子浓度>125×10^(6)/mL时,应对精液样本进行生理盐水稀释。

精子DFI、精子形态学对于男性生育力及辅助生殖技术中的预测价值研究

目的探讨精子DNA碎片指数(DFI)、精子形态学对男性生育力、辅助生殖技术中的预测价值。方法对开封市中医院2021年6月至2022年6月期间人工授精(IUI)的150个周期妊娠结局与DFI之间的相关性进行回顾性分析,观察不同组别(DFI<15%的低DFI组和DFI≥15%的高DFI组)的生化妊娠率、临床早产率、临床妊娠率,结合男方精子形态学、生活方式,分析精子DFI与精子形态学、男性年龄、生活方式的关系。结果在IUI临床结局中,低DFI组生化妊娠率(17.71%)、临床妊娠率(15.62%)高于高DFI组(16.67%、12.96%),但差异无统计学意义(P>0.05);低DFI组IUI临床早产率(3.12%)较低于高DFI组(14.81%),差异有统计学意义(P<0.05);低DFI组精子活力、精子浓度、正常形态率较高DFI组高,差异有统计学意义(P<0.05);精子各参数在正常参考范围的精子DFI较异常精子参数的精子DFI低。不液化精液、精子浓度、活力以及正常形态率低于正常参考值下限的精液DFI较液化精液高于参考下限的精子DFI高,差异有统计学意(P<0.05);不同年龄阶段精子DFI存在明显差异,三组间任意两组精子DFI差异有统计学意义(P<0.05);不同饮酒次数精子DFI存在明显差异,不饮酒和饮酒次数>2次/周、1~2次/周、>2次/周组间差异有统计学意义(P<0.05);吸烟>20支/d组与其他三组比较精子DFI差异有统计学意义(P<0.05);相关性分析发现,精子DFI与精子液化状态、精子活力、精子浓度以及正常形态率呈负相关性,与男性年龄、不良生活方式呈正相关性。结论精子DFI与精子形态学有较强相关性,不良生活方式会提升精子DFI,继而导致男性生育力降低,可见经由观察精子DFI变化可评估男性生育力,但精子DFI变化情况却难以有效预测IUI临床妊娠结局,正因如此临床医师针对生育力较弱的男性,不建议通过检测精子DFI来决策辅助生殖技术方案。

Practical semen analysis： from A to Z

Accurate semen analysis is critical for decisions about patient care, as well as for studies addressing overall changes in semen quality, contraceptive efficacy and effects of toxicant exposure. The standardization of semen analysis is very difficult for many reasons, including the use of subjective techniques with no standards for comparison, poor technician training, problems with proficiency testing and a reluctance to change techniques. The World Health Organization （WHO） Semen handbook （2010） offers a vastly improved set of standardized procedures, all at a level of detail that will preclude most misinterpretations. However, there is a limit to what can be learned from words and pictures alone. A WHO- produced DVD that offers complete demonstrations of each technique along with quality assurance standards for motility, morphology and concentration assessments would enhance the effectiveness of the manual. However, neither the manual nor a DVD will help unless there is general acknowledgement of the critical need to standardize techniques and rigorously pursue quality control to ensure that laboratories actually perform techniques ＇according to WHO＇ instead of merely reporting that they have done so. Unless improvements are made, patient results will continue to be compromised and comparison between studies and laboratories will have limited merit.

A comparative study of the morphometry of sperm head components in cattle, sheep, and pigs with a computer-assisted fluorescence method

The aim of this study was to compare the sperm nuclear and acrosomal morphometry of three species of domestic artiodactyls; cattle （Bos taurus）, sheep （Ovis aries）, and pigs （Sus scrofa）. Semen smears of twenty ejaculates from each species were fixed and labeled with a propidium iodide-Pisum sativum agglutinin （PI/PSA） combination. Digital images of the sperm nucleus, acrosome, and whole sperm head were captured and analyzed. The use of the PI/PSA combination and CASA-Morph fluorescence-based method allowed the capture, morphometric analysis, and differentiation of most sperm nuclei, acrosomes and whole heads, and the assessment of acrosomal integrity with a high precision in the three species studied. For the size of the head and nuclear area, the relationship between the three species may be summarized as bull 〉 ram 〉 boar. However, for the other morphometric parameters （length, width, and perimeter）, there were differences in the relationships between species for sperm nuclei and whole sperm heads. Bull sperm acrosomes were clearly smaller than those in the other species studied and covered a smaller proportion of the sperm head. The acrosomal morphology, small in the bull, large and broad in the sheep, and large, long, and with a pronounced equatorial segment curve in the boar, was species-characteristic. It was concluded that there are clear variations in the size and shape of the sperm head components between the three species studied, the acrosome being the structure showing the most variability, allowing a clear distinction of the spermatozoa of each species.

Study on the Accuracy of Different CASA Systems in the Quality Detection of Fresh Boar Semen

[Objectives]This study was conducted to compare and analyze the accuracy of computer-aided sperm analysis(CASA)and manual method for detecting the quality of fresh boar semen at room temperature.[Methods]Statistical methods such as analysis of variance,ZB score and Z score were used to compare the accuracy of five different brands of CASA systems and manual method to detect the vitality and density of fresh boar semen at room temperature.[Results]After setting the parameters of five CASA systems the same as follows:VCL(curvilinear velocity),VSL(straight-line velocity)≥5μm/s,STR(straightness)=VSL(straight-line velocity)/VAP(average path velocity)≥25%,the sperm motility of six parts of boar semen was tested at normal temperature using different brands of special fixed-volume slides with a uniform chamber height[(20±2)μm].There were no significant differences in sperm vitality detected by the five CASA systems(P>0.05).The ZB scores of the vitality obtained by observers or instrument engineers who did not have a job certificate from the quality inspection department showed that the results of three observers or instrument engineers were unsatisfactory(∣ZB∣>3),but there were no significant differences in vitality between the CASA systems and the inspector with a job certificate(P>0.05).Regarding sperm density detection,when the sperm density was less than 280×106/ml,there were no significant differences between the results displayed by the instruments and the results of the manual hemocytometer counting(P>0.05).[Conclusions]The accuracy of the CASA systems set to uniform parameters was consistent with the accuracy of the visual vitality obtained by an inspector with a job certificate.When the semen was diluted with 3%NaCl solution to a sperm density<280×10^6/ml,the sperm density detected by the CASA systems was consistent in reliability with that obtained by the hemocytometer detection.The CASA systems are faster and more efficient and objective than manual detection,and have the advantages of strong operability and easy promotion.

长期超低温冷冻保存对鞍带石斑鱼精子超微结构及酶活性的影响

为探究长期超低温冷冻保存中鞍带石斑鱼精子质膜、活力、超微结构及酶活性的变化,阐明影响鞍带石斑鱼精子冷冻保存质量的相关机制。实验采集2022年鞍带石斑鱼鲜精及储存时间分别为23、49和61个月的冷冻保存精液,用伊红-苯胺黑染色方法检测精子质膜完整性;用计算机辅助精子分析仪(CASA)检测精子运动参数;测量精浆和精子中琥珀酸脱氢酶(SDH)、过氧化氢酶(CAT)、谷胱甘肽还原酶(GR)、总超氧化物歧化酶(T-SOD)、谷胱甘肽过氧化物酶(GSH-Px)和肌酸激酶(CK)共6种酶活性的变化及三磷酸腺苷(ATP)浓度变化;用扫描电镜和透射电镜观察鲜精和冻精超微结构。结果显示,伊红-苯胺黑染色后,鲜精质膜完整性最高,为83.43%±2.73%,经过超低温冷冻后,精子质膜完整性显著降低,且随着冷冻保存时间的延长而逐渐降低。CASA结果显示,鲜精活力最高,为90.47%±3.34%,经过超低温冷冻后精子活力显著降低,但长期保存23~61个月的精子活力无显著差异,精子活力保持在(63.95%±3.66%)~(68.58%±2.73%),具有稳定的活力,且鲜精与冻精之间精子平均直线运动速度(VSL)、平均曲线运动速度(VCL)和平均路径速度(VAP)均没有显著差异。精子超微结构显示,鲜精形态结构正常、线粒体排列结构规则、形态大小正常。经过超低温冷冻保存后,精子形态结构损伤明显,表现为精子头部质膜破损、细胞质外漏、细胞核膜破损、尾部鞭毛断裂或脱落等。鞍带石斑鱼精浆和精子超低温冷冻前后6种酶活性的变化及ATP含量结果显示,经过超低温冷冻后,精子内SOD、GSH-Px和CAT及ATP含量均显著降低。精浆中酶活性升高,除GR和CAT外,其余酶活性均差异显著。研究表明,长期超低温冷冻对鞍带石斑鱼精浆和精子酶活性、精子活力及精子超微结构均具有较显著的影响。本研究结果为鱼类精子冷冻损伤机理研究积累了丰富的数据,为鱼类精子长期冷冻保存提供了技术参考和评价指标。

Youden图在精子浓度室间质量评价中的应用

目的根据精子浓度室间质量评价(EQA)数据绘制Youden图,以通过EQA回报结果获取更多有效信息,发现系统误差,改进实验室检测质量。方法收集2019和2020年山东省精子浓度EQA数据,绘制Youden图,分析2019和2020年EQA回报结果。结果Youden图显示,2020年低浓度水平质控品变异系数(CV)为31%,显著低于2019年(19%)(P<0.05);高浓度水平质控品CV差异无统计学意义(P=0.097)。结论Youden图可以反映精液分析项目实验室系统误差的趋势,帮助临床实验室更直观地发现系统误差。

A systematic review and meta-analysis to determine the effect of sperm DNA damage on in vitro fertilization and intracytoplasmic sperm injection outcome

Sperm DNA damage is prevalent among infertile men and is known to influence natural reproduction. However, the impact of sperm DNA damage on assisted reproduction outcomes remains controversial. Here, we conducted a meta-analysis of studies on sperm DNA damage （assessed by SCSA, TUNEL, SCD, or Comet assay） and clinical pregnancy after IVF and/or ICSI treatment from MEDLINE, EMBASE, and PUBMED database searches for this analysis. We identified 41 articles （with a total of 56 studies） including 16 IVF studies, 24 ICSI studies, and 16 mixed （IVF ＋ ICSI） studies. These studies measured DNA damage （by one of four assays： 23 SCSA, 18 TUNEL, 8 SCD, and 7 Comet） and included a total of 8068 treatment cycles （3734 IVF, 2282 ICSI, and 2052 mixed IVF ＋ ICSI）. The combined OR of 1.68 （95% Ch 1.49-1.89; P 〈 0.0001） indicates that sperm DNA damage affects clinical pregnancy following IVF and/or ICSI treatment. In addition, the combined OR estimates of IVF （16 estimates, OR = 1.65; 95% CI： 1.34-2.04; P 〈 0.0001）, ICSI （24 estimates, OR = 1.31; 95% Ch 1.08-1.59; P = 0.0068）, and mixed IVF ＋ ICSI studies （16 estimates, OR = 2.37; 95% Ch 1.89-2.97; P〈 0.0001） were also statistically significant. There is sufficient evidence in the existing literature suggesting that sperm DNA damage has a negative effect on clinical pregnancy following IVF and/or ICSI treatment.

Current status and potential of morphometric sperm analysis

The spermatozoon is the most diverse cell type known and this diversity is considered to reflect differences in sperm function. How the diversity in sperm morphology arose during speciation and what role the different specializations play in sperm function, however, remain incompletely characterized. This work reviews the hypotheses proposed to explain sperm morphological evolution, with a focus on some aspects of sperm morphometric evaluation; the ability of morphometrics to predict sperm cryoresistance and male fertility is also discussed. For this, the evaluation of patterns of change of sperm head morphometry throughout a process, instead of the study of the morphometric characteristics of the sperm head at different stages, allows a better identification of the males with different sperm cryoconservation ability. These new approaches, together with more studies employing a greater number of individuals, are needed to obtain novel results concerning the role of sperm morphometry on sperm function. Future studies should aim at understanding the causes of sperm design diversity and the mechanisms that generate them, giving increased attention to other sperm structures besides the sperm head. The implementation of scientific and technological advances could benefit the simultaneous examination of sperm phenotype and sperm function, demonstrating that sperm morphometry could be a useful tool for sperm assessment.