Do Ureaplasma urealyticum infections in the genital tract affect semen quality?

Aim： To investigate the relationship between Ureaplasma urealyticum （UU） infection and semen quality. Methods： From 2001 to 2003, 346 eligible patients aged 20-45 years were invited from two hospitals in Shanghai, China, to participate in an investigation which included questionnaires about general and reproductive health, an external genital tract examination, UU culture and semen analysis. Multiple linear regression models were used to examine whether UU had a significant effect on semen quality after adjustment for confounding factors. Results： Findings suggested that UU infection was associated with higher semen viscosity and lower semen pH value. Sperm concentration was lower in UU positive subjects than that in UU negative subjects （54.04 × 10^6/mL vs.70.58 × 10^6/mL）. However, UU did not significantly affect other semen quality indexes. Conclusion： UU infection of the male genital tract could negatively influence semen quality.

Seminal plasma anti-Müllerian hormone level correlates with semen parameters but does not predict success of testicular sperm extraction （TESE）

Aim： To assess seminal plasma anti-Müllerian hormone （AMH） level relationships in fertile and infertile males. Methods： Eighty-four male cases were studied and divided into four groups： fertile normozoospermia （n = 16）, oligoastheno- teratozoospermia （n = 15）, obstructive azoospermia （OA） （n = 13） and non-obstructive azoospermia （NOA） （n = 40）. Conventional semen analysis was done for all cases. Testicular biopsy was done with histopathology and fresh tissue examination for testicular sperm extraction （TESE） in NOA cases. NOA group was subdivided according to TESE results into unsuccessful TESE （n = 19） and successful TESE （n = 21）. Seminal plasma AMH was estimated by enzyme linked immunosorbent assay （ELISA） and serum follicular stimulating hormone （FSH） was estimated in NOA cases only by radioimmunoassay （RIA）. Results： Mean seminal AMH was significantly higher in fertile group than in oligoasthenoteratozoospermia with significance （41.5±10.9 pmol/L vs. 30.5±10.3 pmol/L, P 〈 0.05）. Seminal AMH was not detected in any OA patients. Seminal AMH wascorrelated positively with testicular volume （r = 0.329, P = 0.005）, sperm count （r = 0.483, P = 0.007）, sperm motility percent （r = 0.419, P = 0.021） and negatively with sperm abnormal forms percent （r = -0.413, p = 0.023）. Nonsignificant correlation was evident with age （r = -0.155, P = 0.414） and plasma FSH （ r = -0.014, P = 0.943）. In NOA cases, seminal AMH was detectable in 23/40 cases, 14 of them were successful TESE （57.5%） and was undetectable in 17/40 cases, 10 of them were unsuccessful TESE （58.2%）. Conclusion： Seminal plasma AMH is an absolute testicular marker being absent in all OA cases. However, seminal AMH has a poor predictability for successful testicular sperm retrieval in NOA cases.

Proteomic analysis of seminal plasma from asthenozoospermia patients reveals proteins that affect oxidative stress responses and semen quality

Asthenozoospermia （AS） is a common cause of human male infertility. In one study, more than 80% of the samples from infertile men had reduced sperm motility. Seminal plasma is a mixture of secretions from the testis, epididymis and several male accessory glands, including the prostate, seminal vesicles and Cowper＇s gland. Studies have shown that seminal plasma contains proteins that are important for sperm motility. To further explore the pathophysiological character of AS, we separated the seminal plasma proteins from AS patients and healthy donors using sodium dodecyl sulfate polyacrylamide gel electrophoresis and in-gel digestion, and then subjected the proteins to liquid chromatography-mass spectrometry （LC-MS/MS） analysis. A total of 741 proteins were identified in the seminal plasma, with a false discovery rate of 3.3%. Using spectral counting, we found that 45 proteins were threefold upregulated and 56 proteins were threefold downregulated in the AS group when compared with the control. Most of these proteins originated from the epididymis and prostate. This study identified a rich source of biomarker candidates for male infertility and indicates that functional abnormalities of the epididymis and prostate can contribute to AS. We identified D J-1--a protein that has been shown elsewhere to be involved in the control of oxidative stress （OS）-as a downregulated protein in AS seminal plasma. The levels of D J-1 in AS seminal plasma were about half of those in the control samples. In addition, the levels of reactive oxygen species were 3.3-fold higher in the AS samples than in the controls. Taken together, these data suggest that downregulation of DJ-1 is involved in OS in semen, and therefore affects the quality of the semen.

Quick recovery and characterization of cell-free DNA in seminal plasma of normozoospermia and azoospermia： implications for non-invasive genetic utilities

We established a quick and reliable method for recovering cell-free seminal DNA （cfsDNA）, by using the binding-washing-elution procedure on the DNA purification column. Low variations （below 15%） among the triplicate values of cfsDNA quantity verified the reproducibility of our cfsDNA recovery method. Similar cfsDNA yield and size distribution between seminal plasma acquired by filtration and centrifugation confirmed the presence of cfsDNA. To investigate the general characterization of cfsDNA, the quantitation and size distribution of cfsDNA from normozoospermic and azoospermic semen were analyzed by real-time PCR and electrophoresis, respectively. CfsDNA concentration in semen with normozoospermia （n = 11） was 1.34 ± 0.65 μg ·mL^-1, whereas a higher cfsDNA concentration was observed in azoospermia （2.56 ± 1.43 μg ·mL^-1, n = 9）. The continuous distribution of DNA fragments ranging from -1 kb to 15 kb and a spectrum of multiples of 180-bp fragments were observed in each normozoospermic and azoospermic sample. Distinct characteristic DNA ladder fragmentations in some azoospermic samples implicated that cfsDNA originate partly from apoptotic cells. CfsDNAs of 36 selected azoospermic patients with known information of Y chromosome microdeletion were subjected to the same microdeletion analysis by multiplex PCR and PCR amplification of sY114 （1 450 bp）. All multiplex PCR reactions with cfsDNA amplified successfully and provided the same result as leukocyte DNA. PCR amplification of sY114 gave a 1 450-bp amplicon as expected. Our data suggested the potential use of cfsDNA in search of biomarker or diagnostic procedures.

Evaluation of deoxyribonuclease activity in seminal plasmaof ejaculated chicken semen

Aim: To confirm the stability of exogenous genes in the generation of transgenic chickens using ejaculated chicken sperm, the deoxyribonuclease (DNase) activity was evaluated in the seminal plasma of ejaculated semen and the stability of DNA was examined by adding lipofection reagents. Methods: A PCR fragment (249 bp) of pEGFPN-1 vector was used as the DNA substrate and was incubated with the seminal plasma at 40 ℃ for 30 min. Then, the whole reaction solution was subjected to agarose gel electrophoresis and the DNA size was evaluated under UV light. Results: The DNA substrate was completely diminished after incubation with seminal plasma. However, the substrate was intact after incubation with heat-treated seminal plasma or incubation with seminal plasma in the presence of 0.5 mmol/L -5 mmol/L EDTA. The substrate was stabilized in the seminal plasma by the addition of commercially available lipofection reagents. Conclusion: The DNase activity is present in the seminal plasma of ejaculated chicken semen. However, DNA is stable in the liposomal-DNA complex.

Beta-endorphin in serum and seminal plasma in infertile men

Aim： To access beta-endorphin levels in serum as well as seminal plasma in different infertile male groups. Methods： Beta-endorphin was estimated in the serum and seminal plasma by enzyme-linked immunosorbent assay （ELISA） method in 80 infertile men equally divided into four groups： non-obstructive azoospermia （NOA）, obstructive azoospermia （OA）, congenital bilateral absent vas deferens （CBVAD） and asthenozoospermia. The results were compared to those of 20 normozoospermic proven fertile men. Results： There was a decrease in the mean levels of betaendorphin in the seminal plasma of all successive infertile groups （mean ± SD： NOA 51.30 ± 27.37, OA 51.88 ± 9.47, CBAVD 20.36 ± 13.39, asthenozoospermia 49.26 ± 12.49 pg/mL, respectively） compared to the normozoospermic fertile control （87.23 ± 29.55 pg/mL）. This relation was not present in mean serum level of beta-endorphin between four infertile groups （51.09 ± 14.71, 49.76 ± 12.4, 33.96 ± 7.2, 69.1 ± 16.57 pg/mL, respectively） and the fertile control group （49.26 ± 31.32 pg/mL）. The CBVAD group showed the lowest seminal plasma mean level of beta-endorphin. Testicular contribution of seminal beta-endorphin was estimated to be approximately 40%. Seminal beta-endorphin showed significant correlation with the sperm concentration （r = 0.699, P = 0.0188） and nonsignificant correlation with its serum level （r = 0.375, P = 0.185） or with the sperm motility percentage （r = 0.470, P = 0.899）. Conclusion： The estimation of beta-endorphin alone is not conclusive to evaluate male reproduction as there are many other opiates acting at the hypothalamic pituitary gonadal axis.

Oxytocin in pig seminal plasma is positively related with in vivo fertility of inseminated sows

Background:Identification of relevant in vivo biomarkers for fertility remains a challenge for the livestock industry.Concentrations of the small peptide hormone oxytocin(OXT),involved in male reproductive function and present in the seminal plasma(SP)of several species could be a robust one.This study characterized concentrations of SPOXT in ejaculates from boars used in artificial insemination(AI)programs aiming to evaluate its relationship with sperm quality variables and in vivo fertility of their liquid-stored AI-semen.Seminal OXT concentrations(ng/mL)were measured in 169 ejaculates from 61 boars of the Duroc,Pietrain,Landrace and Large White breeds using a direct competitive immunoassay test based on AlphaLISA®technology.Ejaculate(ejaculate volume,sperm concentration,total sperm count)and sperm parameters(motility,viability,intracellular generation of reactive oxygen species,plasma membrane fluidity)were assessed at 0 h and 72 h in AI-semen samples stored at 17℃.In vivo fertility included only 18 Large White and Landrace boars whose AI-semen was used to inseminated>100 sows and evaluated both farrowing rate and litter size of 3,167 sows.Results:The results showed that SP-OXT differed between boars and between ejaculates within boar(P<0.05)but not between breeds(Duroc,Pietrain,Landrace and Large White).Ejaculates with higher SP-OXT concentration/mL(hierarchically grouped;P<0.001)had larger volume and came from younger boars(P<0.05).Ejaculates of boars showing positive farrowing rate deviation exhibited higher(P<0.05)SP-OXT concentration/mL than those with negative farrowing rate deviation.Conclusion:The SP concentrations of OXT are boar,ejaculate and age dependent,and positively related with ejaculate volume and farrowing rates of liquid-stored semen AI-doses.

Assessment of seminal plasma laminin in fertile and infertile men

Aim： To assess laminin levels in the seminal plasma of infertile and fertile men, and to analyze the correlation of laminin levels with sperm count, age, sperm motility and semen volume. Methods： One hundred and twenty-five recruited men were equally divided into five groups according to their sperm concentration and clinical examination： fertile normozoospermia, oligoasthenozoospermia, non-obstructive azoospermia （NOA）, obstructive azoospermia （OA） and congenital bilateral absent vas deferens （CBAVD）. The patients＇ medical history was investigated and patients underwent clinical examination, conventional semen analysis and estimation of seminal plasma laminin by radioimmunoassay. Results： Seminal plasma laminin levels of successive groups were： 2.82 ± 0.62, 2.49 ± 0.44, 1.77 ± 0.56, 1.72 ± 0.76, 1.35 ± 0.63 U/mL, respectively. The fertile normozoospermic group showed the highest concentration compared to all infertile groups with significant differences compared to azoospermic groups （P 〈 0.05）. Testicular contribution was estimated to be approximately one-third of the seminal laminin. Seminal plasma laminin demonstrated significant correlation with sperm concentration （r = 0.460, P 〈 0.001） and nonsignificant correlation with age （r = 0.021, P = 0.940）, sperm motility percentage （r = 0.142, P = 0.615） and semen volume （r = 0.035, P = 0.087）. Conelusion： Seminal plasma laminin is derived mostly from prostatic and testicular portions and minimally from the seminal vesicle and vas deferens. Estimating seminal laminin alone is not conclusive in diagnosing different cases of male infertility.

Metabolomic fingerprinting of pig seminal plasma identifies in vivo fertility biomarkers

Background:Metabolomic approaches,which include the study of low molecular weight molecules,are an emerging-omics technology useful for identification of biomarkers.In this field,nuclear magnetic resonance(NMR)spectroscopy has already been used to uncover(in)fertility biomarkers in the seminal plasma(SP)of several mammalian species.However,NMR studies profiling the porcine SP metabolome to uncover in vivo fertility biomarkers are yet to be carried out.Thus,this study aimed to evaluate the putative relationship between SPmetabolites and in vivo fertility outcomes.To this end,24 entire ejaculates(three ejaculates per boar)were collected from artificial insemination(AI)-boars throughout a year(one ejaculate every 4 months).Immediately after collection,ejaculates were centrifuged to obtain SP-samples,which were stored for subsequent metabolomic analysis by NMR spectroscopy.Fertility outcomes from 1525 inseminations were recorded over a year,including farrowing rate,litter size,stillbirths per litter and the duration of pregnancy.Results:A total of 24 metabolites were identified and quantified in all SP-samples.Receiver operating characteristic(ROC)curve analysis showed that lactate levels in SP had discriminative capacity for farrowing rate(area under the curve[AUC]=0.764)while carnitine(AUC=0.847),hypotaurine(AUC=0.819),sn-glycero-3-phosphocholine(AUC=0.833),glutamate(AUC=0.799)and glucose(AUC=0.750)showed it for litter size.Similarly,citrate(AUC=0.743),creatine(AUC=0.812),phenylalanine(AUC=0.750),tyrosine(AUC=0.753)and malonate(AUC=0.868)levels had discriminative capacity for stillbirths per litter;and malonate(AUC=0.767)and fumarate(AUC=0.868)levels for gestation length.Conclusions:The assessment of selected SP-metabolites in ejaculates through NMR spectroscopy could be considered as a promising non-invasive tool to predict in vivo fertility outcomes in pigs.Moreover,supplementing AI-doses with specific metabolites should also be envisaged as a way to improve their fertility potential.

Cytokines in Human Seminal Plasma and Their Effect on Male Fertility

Cytokines are a heterogeneous group of peptides that play an important role in intercellular communication, regulation of innate and specific immunity, hematopoiesis, interaction between the immune system and neuroendocrine network as well as in reproduction and development. Seminal plasma provides an immunological environ- ment for the semen and contains important biological response mediators. Numerous studies investigated the presence of various cytokines in the seminal plasma and tried to correlate cytokine levels with sperm quality and male fertility. However, the patho- physiological significance of seminal cytokines in sperm function is still not completely understood. The purpose of this review is to provide a brief summary of the extensive literature dealing with cytokines in the seminal plasma and to discuss the contribution of local cytokine immunity to male fertility.

Cryopreservation-induced decrease in heat-shock protein 90 in human spermatozoa and its mechanism

<abstract>Aim: To study the protein changes of spermatozoa associated with sperm motility during sperm cryopreservation and its mechanism. Methods: In 18 healthy men, the seminal sperm motility and HSP90 levels were studied before and after cryopreservation using SDS-PAGE, Western blotting and computerized image analysis. Results: The sperm motility declined significantly after cryopreservation (P<0.01). The average grey level and the integrated grey level of sperm HSP90 before cooling were 34.1±3.2 and 243.0±21.6, respectively, while those after thawing were 23.2±2.5 and 105.7±28.5, respectively. Both parameters were decreased significantly (P<0.01). No HSP90 was found in the seminal plasma before and after cryopreservation. Conclusion: HSP90 in human spermatozoa was decreased substantially after cryopreservation. This may result from protein degradation, rather than leakage into the seminal plasma.

PCR analysis of Yq microdeletions in infertile males, a study from South India

AIM: To estimate the frequency of microdeletions in the long arm of Y-chromosome of 20 infertile males from South India. METHODS: Polymerase chain reaction (PCR) amplification using Y-specific STS of azoospermia factor (AZF) regions i.e., SY 84 for AZFa, SY 127 for AZFb and SY 254 for AZFc. RESULTS: Of the 20 infertile subjects 3 (15 %), one azoospermic and two oligozoospermic, showed microdeletions in the AZF region of Y-chromosome. CONCLUSION: The frequency of deletions involving AZF region of the Y-chromosome is 15 % in azoospermic and severely oligozoospermic infertile men. PCR amplification of AZF locus is useful for the diagnosis of microdeletions in the Y-chromosome.

Desmosterol, the main sterol in rabbit semen： distribution among semen subfractions and its role in the in vitro spermatozoa acrosome reaction and motility

Sterols are essential components of the cell membrane lipid bilayer that include molecules such as cholesterol and desmosterol, which are significantly found in the spermatozoa of several animal species. However, the presence of desmosterol in rabbit semen has never been investigated. The aims of this study were to characterize the sterol composition of subfractions of ejaculated rabbit semen and evaluate the in vitro effects of sterol on the spermatozoa acrosome reaction and motility. Two sterols, occurring prevalently in the free form （94.3%）, were identified in whole semen collected from 10 fertile New Zealand White rabbits, specifically desmosterol （58.5% of total sterols） and cholesterol （35.9% of total sterols）. Desmosterol was the predominant sterol found in all subfractions of rabbit semen, varying from 56.7% （in the prostatic secretory granules, PSGs） to 63.8% （in the seminal plasma）. Spermatozoa contained an intermediate proportion of desmosterol （59.8%）, which was asymmetrically distributed between the heads （52.0% of the total content of sterols） and the tails （81.8%）. Results showed that both desmosterol and cholesterol can be transferred from the PSGs to the spermatozoa and are equally effective in inhibiting in vitro spermatozoa capacitation at a concentration higher than 1 mg L^-1. In contrast, neither desmosterol nor cholesterol had a significant effect on spermatozoa motility. Thus, it was concluded that, the various fractions of rabbit seminal fluid differ from each other in sterol composition and quantity, probably due to their different functional properties, and these fractions may undergo significant sterol changes depending on the stage of spermatozoa capacitation.

Relationship between HSP90a, NPC2 and L-PGDS proteins to boar semen freezability

Background： The purpose of this study was to determine the association of three proteins involved in sperm function on the freezability of porcine semen： the heat shock protein 90 alpha（HSP90a）, the Niemann-Pick disease type C2 protein（NPC2）, and lipocalin-type prostaglandin D synthase（L-PGDS）.Six adult boars（each boar was ejaculated three times, 18 in total） were classified by freezability based on the percentage of functionally competent sperm. The male semen with highest freezability（MHF） and the male semen with lowest freezability（MLF） were centrifuged immediately after collection to separate seminal plasma and spermatozoa to make four possible combinations of these two components and to incubate them for 3 h,adjusting the temperature to 17 °C, to freeze them afterwards. The quantification of proteins was performed in two stages： at zero and at 3 h after incubation of the four combinations.Results： The spermatozoa × incubation time（IT） interaction only had effect（P 〈 0.01） on HSP90 a levels; this protein increased in seminal plasma, after 3 h of incubation, in larger quantity（P 〈 0.05） in combinations with MLF spermatozoa. In relation with the NPC2 protein, two isoforms of 16 and 19 kDa were identified. The 19 kDa isoform was affected（P 〈 0.01） only by the seminal plasma × IT interaction, with superior values（P 〈 0.01） both at zero and three hours of incubation, in the combinations with MHF seminal plasma; and 16 kDa isoform was affected（P 〈 0.01） only by the IT with reduction after 3 h of incubation. The levels of L-PGDS was affected（P 〈 0.01）only by the spermatozoa × IT interaction, which reduced（P 〈 0.01） in combinations with MLF spermatozoa after 3 h of incubation.Conclusions： It is possible to consider that the three proteins evaluated were associated with freezability of boar semen due, especially, to the fact that mixtures with MLF spermatozoa showed greater increase levels of the HSP90 a protein and reduction of L-PGDS in plasma. In addition, the seminal plasma of MHF had higher concentration of the NPC2 of 19 kDa protein, which was reduced by incubating with MHF spermatozoa.

Effect of transient scrotal hyperthermia on sperm parameters, seminal plasma biochemical markers, and oxidative stress in men

In this experimental prospective study, we aimed to analyze the effect of transient scrotal hyperthermia on the male reproductive organs, from the perspective of sperm parameters, semen plasma biochemical markers, and oxidative stress, to evaluate whether different frequencies of heat exposure cause different degrees of damage to spermatogenesis. Two groups of volunteers （10 per group） received testicular warming in a 43~C water bath 10 times, for 30 min each time： group 1：10 consecutive days; group 2： once every 3 days. Sperm parameters, epididymis and accessory sex gland function, semen plasma oxidative stress and serum sex hormones were tested before treatment and in the 16-week recovery period after treatment. At last, we found an obvious reversible decrease in sperm concentration （P = 0.005 for Group 1 and P = 0.008 for Group 2 when the minimums were compared with baseline levels, the same below）, motility （P= 0.009 and 0.021, respectively）, the hypoosmotic swelling test score （P-- 0.007 and 0.008, respectively）, total acrosin activity （P = 0.018 and 0.009, respectively）, and an increase in the seminal plasma malondialdehyde concentration （P = 0.005 and 0.017, respectively）. The decrease of sperm concentration was greater for Group 2 than for Group 1 （P = 0.031）. We concluded that transient scrotal hyperthermia seriously, but reversibly, negatively affected the spermatogenesis, oxidative stress may be involved in this process. In addition, intermittent heat exposure more seriously suppresses the spermatogenesis compared to consecutive heat exposure. This may be indicative for clinical infertility etiology analysis and the design of contraceptive methods based on heat stress.

Proteomic profile of seminal plasma in adolescents and adults with treated and untreated varicocele

Varicocele, the most important treatable cause of male infertility, is present in 15% of adult males, 35% of men with primary infertility, and 80% of men with secondary infertility. On the other hand, 80% of these men will not present infertility. Therefore, there is a need to differentiate a varicocele that is exerting a deleterious effect that is treatable from a ＂silent＂ varicocele. Despite the growing evidence of the cellular effects of varicocele, its underlying molecular mechanisms are still eluding. Proteomics has become a promising area to determine the reproductive biology of semen as well as to improve diagnosis of male infertility. This review aims to discuss the state-of-art in seminal plasma proteomics in patients with varicocele to discuss the challenges in undertaking these studies, as well as the future outlook derived from the growing body of evidence on the seminal proteome.

Seminal plasma miR-192a： a biomarker predicting successful resolution of nonobstructive azoospermia following varicocele repair

This study was performed to investigate a potential marker for the presence of spermatozoa in the ejaculate following varicocelectomy in Chinese men with nonobstructive azoospermia and varicoceles. The micro-RNA （miR）-192a levels in seminal plasma and testicular tissue were evaluated by quantitative real-time polymerase chain reaction from 60 men with nonobstructive azoospermia and varicoceles （Group A： 27 men with spermatozoa found in the ejaculate after surgery; Group B： 33 men without spermatozoa found in the ejaculate after surgery） and 30 controls. The seminal plasma and testicular tissue miR-192a levels were higher in Group B than in Group A and the controls （P〈 0.001）, and there was no significant difference between Group A and the controls （P〉 0.05）. Apoptosis and proliferation assays with miR mimics and inhibitors showed that miR-192a induced GC-2 cell apoptosis through the activation of Caspase-3 protein. Thus, seminal plasma miR-192a appears to be a potential marker for successfully indicating spermatozoa in the ejaculate following microsurgical varicocelectomy in men with nonobstructive azoospermia and varicoceles. Seminal plasma miR-192a may be a useful clinical marker for prescreening to determine which patients with nonobstructive azoospermia and varicoceles would benefit from varicocelectomy.

Future directions of clinical laboratory evaluation ol pregnancy

In recent years, our understanding of how the immune system interacts with the developing fetus and placenta has greatly expanded. There are many laboratories that provide tests for diagnosis of pregnancy outcome in women who have recurrent pregnancy loss （RPL） or pre-eclampsia. These tests are based on the premise that immune response to the fetus is equivalent to the adaptive immune response to a transplant. New understanding leads to the concept that the activated innate response is vital for pregnancy and this can result in more effective testing and treatment to prevent an abnormal pregnancy in the future. We describe here only three such areas for future testing： one area involves sperm and semen and factors necessary for successful fertilization; another area would determine conditions for production of growth factors necessary for implantation in the uterus; finally, the last area would be to determine conditions necessary for the vascularization of the placenta and growing fetus by activated natural killer （NK） cells （combinations of killer cell immunoglobulin-like receptor （KIR） family genes with HLA-C haplotypes） that lead to capability of secreting angiogenic growth factors. These areas are novel but understanding their role in pregnancy can lead to insight into how to maintain and treat pregnancies with complicating factors.

Serum amyloid P component:a new biomarker for low sperm concentration?

Serum amyloid P component(SAP)is present in seminal plasma,on spermatozoa,and in different tissues of the male reproductive tract,but its function is not known.The aims of this study were to determine if the concentration of SAP in seminal plasma is associated with commonly assessed semen parameters and to investigate if SAP could be a new,indirect biomarker for these parameters.In a cross-sectional study of 203 young volunteers,the concentration of SAP in seminal plasma was measured with a in-house developed enzyme-linked immunosorbent assay.Scatter plots,Pearson’s correlation coefficients(r),and linear regression models were produced,and SAP showed a statistically significant correlation with sperm concentration(r=0.75),sperm number(r=0.68),semen volume(r=-0.19),progressive sperm motility(r=0.24),and sperm immotility(r=-0.20).When the study group was dichotomized,SAP could be used to discriminate samples with a sperm concentration<or≥5×10^(6)ml^(-1),15×10^(6)ml^(-1),or 40×10^(6)ml^(-1),and in receiver operating characteristic curves,the corresponding areas under the curves were 0.97,0.93,and 0.82,respectively,with P<0.001 for all three cutoff values studied.The concentration of SAP in seminal plasma showed a strong,positive correlation with the concentration of spermatozoa in semen.SAP may be used as a new indirect potential biomarker for sperm concentration in fresh and in frozen,stored samples.In addition,it is envisaged that the assay could be developed into a home fertility test to differentiate between a low and a normal sperm concentration.