少、弱精子症患者精浆、精子和血清中锌及性激素水平的相关分析

目的:检测弱精子症和少弱精子症患者精浆、精子、血清中锌含量和血清性激素水平,分析锌含量和血清性激素水平的变化与精子密度和精子运动能力的关系。方法:随机筛选190例弱精子症患者,85例少弱精子症患者以及32例精液质量正常的已生育男性作为研究对象,利用原子吸收光谱法检测其精浆、精子和血清锌含量,放射免疫分析法检测血清生殖激素(FSH、LH、T),并进行统计学分析。结果:3组间精浆锌和血清锌含量没有显著差异(P>0.05);少弱精子症患者精子锌含量显著高于弱精子症患者和正常生育男性(P<0.01);弱精子症患者T含量显著低于正常生育组而LH含量显著高于正常生育组(P<0.05);少弱精子症患者T含量显著低于正常生育组而FSH含量显著高于正常生育组(P<0.05),并且其LH含量与正常生育组间具有统计学意义(P<0.01);弱精子症、少弱精子症患者精浆锌与血清T之间无明显的相关性(P>0.05)。结论:少弱精子症患者过高的精子锌含量可能与精子运动能力下降和精子膜功能障碍相关。但其具体机制还有待进一步研究。血清生殖激素(FSH、LH、T)的测定对于弱精子症、少弱精子症病因的诊断和治疗具有一定的临床意义。     

Sperm Na+, K+-ATPase α4 and plasma membrane Ca2+-ATPase (PMCA) 4 regulation in asthenozoospermia

Asthenozoospermia, which is characterized by reduced motility, is one of the etiologies of male infertility. Its biochemical and functional consequences include altered ATPase activity. This study investigated the activities of Na⁺, K⁺-ATPase and Ca²⁺-ATPase and the expression of Na⁺, K⁺-ATPase α4 and PMCA4 isoforms in human sperm of asthenozoospermic infertile men. Nineteen samples from asthenozoospermic infertile couples were examined in this study. Computerized-assisted semen analysis (CASA) was performed, and the enzyme activity was measured based on the ability of ATPase to release organic phosphate from ATP as a substrate. The Na⁺, K⁺-ATPase α4 and PMCA4 isoform expression levels were measured by western immunoblotting, whereas the protein distribution was examined by immunocytochemistry. This showed that the Na⁺, K⁺-ATPase activity and the Na⁺, K⁺-ATPase α4 isoform expression were lower in the asthenozoospermia group than in the normozoospermia group (8.688±1.161 versus 13.851±1.884 µmol Pi/mg protein/h, respectively; p>0.05). In contrast, the Ca²⁺-ATPase activity was significantly higher in the asthenozoospermia group than in the normozoospermia group (11.154±1.186 versus 2.725±0.545 µmol Pi/mg protein/h, respectively; p<0.05). In comparison, PMCA4 expression in the asthenozoospermia group was lower than in the normozoospermia group (p>0.05). The altered ATPase activity and isoform expression in asthenozoospermia may impair sperm structure and function.     

H3K4me2 accompanies chromatin immaturity in human spermatozoa: an epigenetic marker for sperm quality assessment

ABSTRACT

Chromatin remodeling, including histone post-translational modifications, during spermatogenesis can affect sperm quality and fertility, and epigenetic marks may therefore be useful for clinical evaluations of sperm. Together with histone hyperacetylation, the dimethylation of histone H3 on lysine K4 (H3K4me2) is also required during protamination. Accordingly, we evaluated the utilization of this epigenetic mark for the identification of sperm with decrease quality and immature chromatin. In this study, 99 semen samples, including 22 normozoospermic (N), 63 asthenozoospermic (A), and 14 oligoasthenozoospermic (OA) samples, were comprehensively analyzed with respect to H3K4me2 levels, DNA damage (DNA fragmentation index, DFI), and sperm immaturity (high DNA stainability, %HDS), as determined by a sperm chromatin structure assay using flow cytometry. We detected a significant relationship between H3K4me2 and %HDS (r = 0.47; p < 0.001). Furthermore, we observed negative correlations between H3K4me2 and sperm concentration, motility, and mitochondrial activity (p < 0.05). The increase in immaturity as semen quality decreased (N > A > OA) indicates the importance of chromatin immaturity and histone code deviations in sperm evaluations. Using various approaches, our study elucidated H3K4me2 as a molecular marker of sperm quality with potential use in reproductive medicine.

Abbreviations: A: asthenozoospermic; AO: acridine orange; ART: assisted reproductive therapy; BWW: Biggers-Whitten Whittingham; DAPI: 4?,6? -diamidino-2-phenylindole; DFI: DNA fragmentation index; H3K4me2: dimethylation of lysine K4 on histones H3; HDS: high DNA stainability; HRP: horseradish peroxidase; MACS: magnetic-activated cell sorting; N: normospermic; NGS: normal goat serum; OA: oligoasthenozoospermic; PTM: post-translational modification; SCSA: sperm chromatin structure assay; SUTI: sperm ubiquitin tag assay; TBS-T: TBS with 0.5% Tween-20     

The Expression of Mannose-Ligand Receptor is Correlated with Sperm Morphology

The objective of the present study was to evaluate the association between the expression of sperm mannose-ligand receptors and sperm morphology. Sperm samples were obtained from 45 men, 30 fertile sperm donors and 15 infertile men. Sperm concentration, motility and morphology were evaluated and then incubated with control medium (Ham's F-10 + 1% HSA) for 4 h. Expression of mannose-ligand receptors was evaluated by mannosylated-BSA-FITC (subdivided into 3 patterns: I, for uncapacitated sperm; II, for capacitated; and III, for acrosome-reacted sperm). The mean ( &#45 SE) frequencies of sperm cells of the total sperm population that expressed patterns I, II, and III were 88 &#45 2.1%, 7 &#45 1.6%, and 5 &#45 0.8%, respectively, for fertile men, and 90 &#45 2.1%, 7 &#45 1.3%, and 3 &#45 0.5%, respectively, for infertile men. The rate of pattern III expression of mannose-ligand receptors was significantly higher in the fertile group compared to the infertile patients ( p <. 01). A poor but significant correlation was observed between the rate of pattern III and the percentage of normal-forms sperm cell in the ejaculate ( r =. 35, p =. 018). Fertile sperm samples express more advanced patterns of mannose-ligand receptors compared to infertile men. This phenomenon is related to the morphology of human sperm cell in the ejaculate more than to any other basic sperm characteristics.     

SPERM MORPHOLOGY AND CHROMATIN CONDENSATION BEFORE AND AFTER SEMEN PROCESSING

Semen analysis constitutes the most important investigation of male infertility. However, the true anomalies present in defective sperm cells have been only partially characterized. The integrity of the sperm chromatin may play the most important role, particularly in ICSI, where most of the natural selection mechanisms are bypassed. This study was carried out to characterize sperm morphology (strict criteria), to evaluate chromatin condensation and sperm count in native semen as well as after semen preparation by the swim-up technique, and to eventually evaluate any correlation between these parameters. Semen from 90 men was analyzed for the above parameters in both the fresh and processed semen. Whereas the sperm count decreased after sperm preparation by the swim-up technique in comparison to the value in the fresh semen (p&lt;.001), there was an increase in the percentage of morphologically normal (p&lt;.001) and chromatin-condensed sperm (p=.99). However, there was no correlation between sperm morphology, chromatin condensation, and sperm count either in the fresh or in the processed semen samples. These results suggest that sperm morphology, sperm count, and chromatin condensation are independent parameters that should be evaluated separately in the assessment of male fertility in an assisted reproduction program.     

三种精子处理方法对精子存活时间的影响

目的:探讨浓度梯度离心法、上游法和未经处理精子三种不同精子处理方法对精子存活时间的影响。方法:随机研究男科实验室患者15例,手淫取精后精液标本分为三组6份,未经处理的精子组为A组;浓度梯度离心法处理精子为B组;上游法处理精子为C组。每组又分为室温(25℃)和体温(37℃)组。每天(间隔24 h)光学显微镜观察精子的活率、前向运动,EY(伊红)染色评估精子死亡情况,直到精子全部死亡后2天。结果:三组在25℃室温与37℃体温下比较,显著延长精子存活时间,差异有统计学意义(P<0.05);B、C组与A组比较,体温及室温均(B组:11.6和28天;C组:9.5和26.7天;A组3.1和18.9天)显著延长精子存活时间,差异有统计学意义(P<0.05)。结论:精子处理后显著延长其存活时间,包括活率和前向运动;精子在25℃室温较37℃体温下显著延长精子存活时间。     

精子成熟过程中鞭毛蛋白的变化

精子功能成熟是指精子在附睾运行过程中逐渐获得运动和受精的能力。近年来,随着基因敲除和过表达等基因功能研究技术的发展和应用,发现精子鞭毛蛋白的变化与修饰在精子成熟过程中发挥重要作用。例如:在附睾中,精子内3磷酸甘油醛脱氢酶(glyceraldehyde 3-phosphate dehydrogenase,GAPDH)数量增加并结合至鞭毛纤维鞘上,目的是参与糖酵解过程为精子供能;又如,同样结合在纤维鞘上的激酶锚定蛋白4(a kinase anchoring protein 4,AKAP4)在附睾中发生磷酸化,介导鞭毛运动。综述精子鞭毛蛋白的最新研究进展,包括鞭毛蛋白数量、结构和功能的变化,为进一步阐明精子运动、临床弱精子症等生理与病理机制以及阻断精子运动的男性避孕疫苗研发提供参考。     

Human Follicular Fluid Stimulates the Motility of Washed Human Sperm

Human follicular fluid (hFF) was collected by laparoscopic oocyte pickup during IVF to evaluate the effect of hFF on human sperm motility with a transmembrane migration method. Freshly ejaculated human sperm were washed with phosphate buffered saline (PBS) and mixed with either PBS or hFF. Amplitude of motility increases were 38% and 72% in washed fertile sperm and washed asthenozoo-spermic sperm when individual control motility was considered to be 100%. The stimulatory effect of hFF was lost when preheated at 100°C for 30 minutes. hFF collected from mature follicles stimulated sperm motility better than that collected from intermediate or immature follicles. hFF did not stimulate the motility of unwashed sperm in freshly ejaculated human semen. A heat labile factor(s) in hFF may stimulate the motility of washed human sperm. Whether this factor could be used to improve the success rate of IVF and artificial insemination awaits further investigation.     

精液分析中精液质量分析仪的应用

用常规的精液分析方法和精液质量分析仪(Sperm Quality Analyzer, SQA)对110份不同质量及来源的精液样本进行了分析。通过对常规分析的各精液参数与SQA测得的精子活力指数(Sperm Motility Index, SMI)及其对应的精液参数间的相关分析,显示SMI值与常规分析的精子密度、活动精子密度、活动率、活动度指数(Motility Index, MI)显著相关,SQA与常规分析两方法分别得到的精子密度、活动率间有较好的相关性;正常精液与异常精液的SMI值有显著性差异;SMI值用于诊断精子密度异常的敏感性为96.6％,特异性为74.1％。本研究认为精液质量分析仪重复性好,可客观地对精液的活动精子密度和活动力作出综合评价,SMI值在不育症的诊断中有一定的临床意义,但尚有一定的局限性,不能完全替代全面的传统的精液分析。     

Relationship Between Hypoosmotic Swelling Test,Semen Analysis,and Zona-Free Hamster Ovum Test

The hypoosmotic swelling test is a simple test for measuring the functional competence of the human sperm membrane. Fifty-four patients with idiopathic infertility were assessed by hypoosmotic swelling test and the results were compared with those of routine semen analysis and zona-free hamster ovum human sperm penetration test (ZSPT). Semen samples with abnormal semen parameters had lower percentage of swollen sperm in comparison with those with normal semen parameters. A positive correlation was observed between sperm concentration and sperm swelling (r -. 50, p <. 05). A strong positive correlation was observed between the percentage of sperm motility and the percentage of swollen sperm (r - 0.60, p <. 01), and between motile sperm concentration and sperm swelling (r -. 62, p <. 01). On the other hand, sperm swelling correlated only weakly with the percentage of sperm penetration. The results indicate that the hypoosmotic swelling test appears to evaluate different functional qualities of sperm than ZSPT.     

精子在附睾成熟中鞭毛蛋白的研究进展

精子功能成熟是指精子在附睾运行过程中逐渐获得运动和受精的能力。近年来,随着基因敲除和过表达等基因功能研究技术的发展和应用,发现精子鞭毛蛋白的变化与修饰在精子成熟过程中发挥重要作用。例如：在附睾中,精子内3磷酸甘油醛脱氢酶（glyceraldehyde 3-phosphate dehydrogenase,GAPDH）数量增加并结合至鞭毛纤维鞘上,目的是参与糖酵解过程为精子供能;又如同样结合在纤维鞘上的激酶锚定蛋白4（a kinase anchoring protein4,AKAP4）在附睾中发生磷酸化,介导鞭毛运动。综述精子鞭毛蛋白的最新研究进展,包括鞭毛蛋白数量、结构和功能的变化,为进一步阐明精子运动、临床弱精症等生理与病理机制以及阻断精子运动的男性避孕疫苗研发提供参考。     

The ultrastructure and metabolism of ejaculated tammar wallaby sperm are impaired by swim-up procedures when compared with sperm from the cauda epididymidis

The metabolism, rate of intracellular accumulation of sugars, motility and ultrastructure of ejaculated tammar sperm were impaired by swim-up into artificial media, particularly when the cells were subsequently exposed to N-acetyl-D-glucosamine (NAG). The inclusion of hyaluronate, serum albumin, catalase or Desferal in swim-up media helped prevent deterioration of sperm motility, but failed to prevent detrimental NAG-induced metabolic and ultrastructural changes. However, the sperm were unavoidably diluted during swim-up into artificial media and their behavioural properties were modified by dilution. Thus, sperm collected from the cauda epididymidis were immotile and their rate of oxygen uptake was low in undiluted caudal epididymal semen (CES). Nevertheless, these sperm were viable, and vigorous motility was induced by 5- to 50-fold dilution in Krebs-Ringer phosphate (KRP). Sperm respiration also dramatically increased with moderate dilution (5- or 15-fold) in KRP, but decreased again at higher rates (50-fold). This suggested that motility and the metabolic properties of tammar sperm are modified both by dilution and on leaving the suppressing conditions of the epididymis. Diluted tammar epididymal sperm also displayed a Pasteur effect, but rapidly lost capacity for motility in an oxygen-depleted atmosphere. It was concluded that swim-up procedures compromise ejaculated tammar sperm by promoting dilution-induced changes. This may alter the permeability of the membrane with loss of the enzymes that process the ammonia generated during the metabolism of NAG in seminal plasma. Subsequent exposure to NAG further promotes ultrastructural damage culminating in loss of viability.     

甲醛对雄性小鼠生殖细胞的毒性

目的 研究甲醛对小鼠睾丸生殖细胞的一般毒性及对睾丸组织中山梨醇脱氢酶(SDH)活性的影响。方法 选用雄性昆明种小鼠为研究对象。甲醛染毒剂量分别为0.20、2.00、20.00 mg/kg。采用腹腔注射染毒5 d,观察睾丸组织的病理改变及SDH活性;进行精子计数并观察精子头畸形。结果 甲醛导致小鼠生殖细胞变性,坏死;随染毒剂量增加,精子数减少(P<0.01),精子头畸形率升高(r=0.953,P<0.01);睾丸组织中SDH的活性降低(P<0.01)。结论 甲醛具有小鼠生殖细胞毒性,SDH是甲醛生殖细胞损伤的生物效应标志物,精子头畸形率是判断环境中甲醛对生殖细胞一般毒性及其遗传物质损伤的检测指标。     

AGGREGATION OF HUMAN SPERM AT HIGHER TEMPERATURE IS DUE TO HYPERACTIVATION

Chemotaxis of sperm cells to chemicals and hormones, such as progesterone, helps us to understand the concept of sperm transport. Here, the hypothesis was that heat increased sperm hyperactive motility, which caused the sperm to aggregate at the higher temperature. The objectives were (1) to determine the concentration of sperm at both halves of an artificial female reproductive tract made from a hermetically sealed cryopreservation straw filled with culture medium and placed with each end at different temperatures, and (2) to analyze the motility or kinematic parameters and hyperactivation of sperm found at the different temperatures. Cryopreserved-thawed human donor sperm (N = 6) were pooled and processed through 2-layer colloid solution. Analyses of the motile sperm were carried out and the washed sperm were homogeneously mixed and pipetted into several 0.5-mL French cryopreservation straws and heat-sealed. The control substance, consisting of acid-treated sperm, was also placed in several straws. The plastic straws of sperm were placed half at 23oC and half was at either 37 or 40oC. After 4 h, sperm at different sections of the straws were analyzed using the Hamilton Thorn motility analyzer (HTM-C). After 4 h of incubation, the concentration of sperm was doubled at the 40oC heated half of the straw when compared with the other half of the straw at 23oC. There were no differences in sperm concentration in the straw kept half at 37oC and half at 23oC. There were significantly higher percent motility, mean average path velocity, straight line velocity, lateral head displacement, and percent hyperactivation in sperm at the 40oC tempera ture. The aggregation of sperm at the higher temperature of 40oC may be due to enhanced motility, increased sperm velocities, and a 10-fold increase in hyperactivation at that temperature. The 37oC temperature was not sufficient to attract sperm. Sperm cells migrating into the higher temperature site of ovulation begin nonprogressive hyperactivation movement, which is the physiological ''brake" to detain the sperm at the site of ovulation.     

LESS NO PRODUCTION AND BETTER MOTION PARAMETER IN HUMAN SPERM BY SWIM-UP PROCESSING

Fifteen semen specimens were obtained from men for semen analysis; each was divided into two aliquots for prepararation. The motile sperm recovery rate, percentage motility, and motion parameters were measured for each semen specimen (n?=?15) before and after preparation with the use of the two methods, and cultured with different time courses (1?hr, 3?hr, and 6?hr). Nitric oxide (NO) was measured using the chemiluminscence method after centrifugation. Recovery rate of motile cell was significantly higher in direct swim-up method (69.5?±?42.4% versus 49.3?±?29.3%, p?<?0.05). In motility, direct swim-up method in the different time courses was significantly better than IxaPrep method. (1?hr: 91.1?±?5.2% vs 65.6?±?16.4%, 3?hr: 87.2?±?7.9% vs 65.2?±?16.5%, 6?hr: 86.1?±?7.5% vs 60.8?±?17.6% and prewash: 61.6?±?16.2%, p?<?0.05). In VAP and VSL, the sperm prepared by the above two methods all improved compared to pre-wash sperm (p?<?0.05), but there was no statistical significance between the two methods. NO production in the direct swim-up group was significantly lower than IxaPrep group in the first hour of culture (0.09?±?0.09?uM vs 0.15?±?0.09?uM, p?<?0.05). NO production increased as the culture time increased in swim-up group, but conversed in IxaPrep group. The lower level of NO produced in the swim-up group may suggest that better sperm quality achieved is due to the decreased NO production.     

Effect of Caffeine on Human Sperm Penetration into Zona-Free Hamster ova

The effect of caffeine on spermatozoal ability to penetrate zona-free hamster ova was examined on fresh and frozen-thawed semen samples. The mean motility of 10 fresh semen samples incubated with caffeine significantly increased from 29% to 35%. Sperm penetration into zona-free hamster ova did not differ between the control group and the specimens to which caffeine was added. The same effect of caffeine on sperm motility and hamster ova penetration was noted in the frozen-thawed sperm samples. Motility was enhanced by 21%, but hamster ova penetration did not significantly change. The increase in sperm motility caused by caffeine does not change the fertilizing ability of fresh and frozen-thawed human sperm.     

EFFECT OF TYROSINE KINASE INHIBITORS ON TYROSINE PHOSPHORYLATION AND MOTILITY PARAMETERS IN HUMAN SPERM

Tyrosine phosphorylation has recently been associated with capacitation and suggested as a regulator of sperm movement, especially characterizing hyperactivation. The objective of this study was to verify if tyrosine phosphorylation of human sperm proteins was essentially required for the maintenance of motility as well as the development of hyperactivation. Washed sperm were incubated for 6 h in Ham's F10 + 0.35% HSA at 37°C in 5% CO 2, with and without the tyrosine kinase inhibitors genistein, tyrphostin, erbstatin, or herbimycin A and the wide-spectrum kinase inhibitor staurosporin. The concentrations of the inhibitors used in the experiments did not induce sperm toxicity, as measured by membrane integrity and mitochondrial function assays. Samples incubated without the inhibitors (control), increased their tyrosine kinase activity (ELISA), the number and intensity of tyrosine-phosphorylated (PY) protein bands (Western blot), the incidence of PY-immunoreactive sperm (immunofluorescence), and some of the sperm motion characteristics (CASA), such as velocity (VEL), amplitude of lateral head displacement (ALH), and hyperactivation. Among the selective protein tyrosine kinase inhibitors, genistein was the most active and consistent, inhibiting sperm tyrosine kinase activity, PY proteins, incidence of PY sperm, and sperm motility and motion parameters, such as VEL, ALH, and hyperactivation. The rest of the kinase inhibitors decreased motion characteristics to a varied extent and had different effects on phosphorylation parameters. In general, they decreased PY phosphorylation of 2 proteins (83 and 54 kDa) present in whole sperm extracts, and two sets of proteins of low (39-49 kDa) and medium (55-87 kDa) molecular weight present in the Triton X-100-solubilized sperm protein fraction. Thisinhibition was evident regardless of the total tyrosine kinase activity of the samples or the incidence of PY-immunoreactive sperm. The described findings further support the association between motility and protein tyrosine phosphorylation in human sperm and point to certain proteins as the main linkers.     

Associations between biochemical components of human semen with seminal conditions

The aim of the study was to assess whether abnormal levels of seminal biochemical components could be associated with semen alterations and infertility. In this study, 92 human ejaculates from selected men were analyzed. Albumin, estradiol, ferritin, total proteins (TP), folic acid (FA), vitamin B12, alkaline phosphatase (ALP), creatine kinase (CK), gamma-glutamyl transpeptidase (GGT), lactate dehydrogenase were evaluated. Semen parameters and biochemical components of the 92 samples were correlated bySpearman’s rho coefficient. Albumin showed a negative correlation with sperm progressive motility and vitality (P < 0.05), CK with sperm concentration and vitality (P < 0.05), ferritin with sperm morphology (P < 0.05). FA negatively correlated with sperm concentration (P < 0.05) and GGT with sperm motility (P < 0.05). The values of biochemical components were compared for each semen parameters (concentration, motility, morphology, vitality) in samples ≤5th percentile with those >5th percentile and in patients with/without leukocytospermia, presence/absence of germ cells, increased/normal viscosity by Mann Whitney U test. The albumin (P < 0.001) and TP (P < 0.05) levels and the GGT activity (P < 0.001) were significantly higher in patients with sperm motility ≤5th percentile. Patients with sperm vitality ≤5th percentile showed increased albumin concentration (P < 0.01) and the CK activity (P < 0.001). The presence of germ cells in semen was concomitant with high values of ferritin (P < 0.01); the ALP activity (P < 0.01) and FA level (P < 0.001) were decreased in hyperviscous semen. The FA and estradiol levels were significantly decreased in the smoker group compared to those measured in the non-smoker group. Subjects were grouped in infertile patients and men with unknown reproductive potential. Infertile patients albumin and ferritin were significantly increased (P < 0.05). This study suggests that some biochemical components may be associated with human seminal pathological conditions.

Abbreviations: ALP: alkaline phosphatase; LDH: lactate dehydrogenase; GGT: γ-glutamyl transferase; CK: creatine kinase; ACP: acid phosphatase; ALB: albumin; TP: total proteins; FERR: ferritin, E: estradiol; FOL: folic acid; B12: vitamin B12; FSH: follicle stimulating hormone; LH: luteinizing hormone; T: testosterone; BMI: body mass index; WHO: World Health Organization.     

Temporal trends in bull semen quality: A comparative model for human health?

Introduction

A decline in human semen quality over the past 30-60 years has been reported in numerous epidemiological studies from the United States and Europe. We evaluated temporal trends in semen quality parameters in dairy bulls. The long-term management of dairy bulls for artificial insemination presented a unique opportunity to evaluate temporal trends in semen quality and explore this relationship as a potential animal model for reproductive abnormalities in humans.

Materials and methods

Bull semen analysis data from 1965 through 1995 were collected from a large artificial insemination organization. Semen analyses from 12- to 18-month-old Holstein dairy bulls were included in the study and consisted of daily sperm concentration, daily ejaculate volume, total daily sperm output, percentage of sperm with normal morphology, and percentage of sperm with normal post-thaw motility. Multiple regression analysis, logistic regression, and general linear modeling were used to determine temporal trends over the 30-year period.

Results and discussion

Semen quality appears to have declined from 1970 to 1980 or 1985 as manifested by declines in daily ejaculate volume, daily sperm concentration, and total daily sperm output. In contrast, sperm morphology and motility improved over the same period. In approximately 1980 or 1985, depending on the parameter, ejaculate volume, sperm concentration, total sperm, and motility improved. However, normal morphology began to deteriorate during this same period. Methodological inconsistencies over time introduce uncertainty in analyses of temporal trends in semen quality in this and previous human studies. However, changes in technology do not appear to be solely responsible for the temporal trends observed. The source of the decline in semen quality in the bulls studied is unknown. If the decline in semen quality were due to exposure to endocrine disrupting chemicals, then a continued decline or a leveling-off would be expected. Instead, a rise in semen quality was observed during the latter portion of the observation period.     

生育和不育男性精液维生素B_(12)、叶酸、活性氧和精子质量的比较

为了探讨精液维生素 B1 2 (VB1 2 )、叶酸和活性氧 (ROS)对精子质量和生殖功能的影响。收集成年男性不育者 44名 (不育组 )和经证实配偶已怀孕的健康成年男性 176名 (生育组 )的精液 ,根据 WHO推荐方法检测精子质量指标 ,并测定精液 VB1 2 、叶酸和 ROS水平。结果显示二组 VB1 2 和叶酸没有显著性差异 (P>0 .0 5 ) ,不育组 ROS和形态异常精子都显著高于生育组 (P<0 .0 1) ,ROS与精子形态异常呈正相关 (P<0 .0 1) ,VB1 2 和叶酸与 ROS均呈负相关 (P<0 .0 1)。结论认为精液 ROS升高 ,可能促使精子形态异常 ,从而影响男性生殖功能。