The relationship between acridine orange fluorescence of sperm nuclei and the fertilizing ability of human sperm

Azilsartan as a preventive agent against cyclophosphamide-induced testicular injury in male rats

Cyclophosphamide (CP) is a popular cancer treatment; however, despite its efficacy, it is known to cause harm to the testicles. To mitigate the reproductive damage caused by CP in male rats, we examined the protective effect of azilsartan (AZ) on CP-induced testicular damage. Thirty Sprague-Dawley male rats were equally divided into three groups: normal control group: received 0.5% CMC suspension for 13 days; induction group: received a single dose of 200 mg/kg of CP on day 6 by intraperitoneal (IP) injection, azilsartan group: received azilsartan (4 mg/kg) orally for 5 days followed by a single dose of 200 mg/kg of (CP) on day 6 by IP injection, then azilsartan administered again for 7 days. Animals were sacrificed on day 14, and sperm characteristics, testosterone levels, and testicular histopathology were evaluated. Induction with CP caused a significant reduction in median value compared to normal control in sperm count (12.0 vs. 22.0 × 106/mm3), sperm motility (30 vs. 90%), abnormal sperm (30.32 vs. 14.43%), dead sperm count (32.43 vs. 10.49 × 106/mm3), DNA fragmentation (21.57 vs. 5.49%); meanwhile, azilsartan prevent these effects on median sperm count (17.0 × 106/mm3), sperm motility (70.0%), abnormal sperm (23.19%), dead sperm count (26.17 × 106/mm3), DNA fragmentation (13.81%), and improved plasmatic testosterone levels compared to the CP group and prevented histopathological alterations of the testes. Azilsartan's mitigation of CP's effects suggests it can prevent male rats' reproductive damage caused by CP. One possible explanation for AZ's protective effects is that it inhibits lipid peroxidation and has antioxidant properties.

Looking with new eyes: advanced microscopy and artificial intelligence in reproductive medicine

Microscopy has long played a pivotal role in the field of assisted reproductive technology (ART). The advent of artificial intelligence (AI) has opened the door for new approaches to sperm and oocyte assessment and selection, with the potential for improved ART outcomes.

Heparin and Progesterone Exert Synergistic Effects to Improve the In-Vitro Fertilization Rate of Bovine Sperm Bound to Oviduct Cell Aggregates from the Isthmus

Simple Summary

After mating, sperm starts its long journey with the ultimate goal of fertilizing the oocyte. Inside the oviduct, sperm is attached to the surface of epithelial cells. The intact and good-quality sperm are elected and stored. Many infertility-related problems are related to the short life span of the sperm and/or the delay of the capacitation process of sperm attached to the oviduct. Thus, the elongation of the life span of the sperm would be very helpful in overcoming such problems. We hereby aimed to evaluate the fertilization ability of sperm that bind to cell aggregates oviduct (infundibulum-ampulla-isthmus), and assess the effect of heparin and or progesterone on the in-vitro fertilization ability of sperm co-incubated with isthmus cells aggregates. The sperm bound to isthmus aggregates improved the rate of in-vitro fertilization compared to infundibulum and ampulla. Moreover, pre-treatment of mature oocytes with heparin and progesterone plays a coactive role that improves the in-vitro fertilization of sperm bound to cell aggregates from isthmus. In conclusion, binding to isthmus aggregates improves the in-vitro fertilization of bovine sperm. Additionally, heparin together with progesterone, exerts a synergistic action that improves the in-vitro fertilizing potential of sperm attached to isthmus aggregates.

Abstract

After the copulation process, some sperm start the long journey with an ultimate goal of fertilizing the oocyte. Inside the oviduct, sperm are stored, waiting for the ovulated oocyte where they bind to the apical surface of the oviduct cells, which in turn hold sperm to form a sperm nest. The essential functions of the sperm reservoir include attaching spermatozoa to oviduct epithelial cells, selecting intact, good-quality sperm with an end result of extending sperm life expectancy. The current study aimed to evaluate the fertilization ability of sperm that bind to cell aggregates from different parts of the oviduct (infundibulum-ampulla-isthmus), and to assess the effect of heparin and or progesterone (P4) on the in-vitro fertilization ability of sperm co-incubated with cell aggregates from the isthmus. In-vitro fertilization was identified as a cleaved oocyte to two cells or more. The sperm bound to cell aggregates from the isthmus improved the rate of in-vitro fertilization (48.09%) compared to aggregates from the infundibulum (36.90%) and ampulla (37.61%). Moreover, pre-treatment of mature COCs with heparin (40 μg/mL) and P4 (80 nanomolar) play a coactive role that improves the in-vitro fertilization ability of sperm bound to cell aggregates from isthmus (63.33%), compared to 42.61% in the absence of cells aggregates. In conclusion, binding to cell aggregates from isthmus improves the in-vitro fertilization ability of Bovine sperm. Additionally, heparin, together with P4, exerts a synergistic action that improves the in-vitro fertilizing potential of sperm attached to cell aggregates from the isthmus of the bovine oviduct.

DNA damage in human sperm: The sperm chromosome assay

Background

Sperm DNA damage is a major cause of pre‐ and post‐implantation embryonic loss in humans. However, the factors that control how and when such DNA damage occurs in human sperm are poorly understood.

Methods

Here, I review information relating to sperm DNA damage that can be obtained from the sperm chromosome assays described in the existing literature.

Main findings

The sperm chromosome assays, which consist of interspecific in vitro fertilization or intracytoplasmic sperm injection using murine oocytes and subsequent chromosome analysis, indicate that the proportion of sperm showing DNA damage is initially low and there are larger numbers of sperm with potential membrane and DNA damage that are induced after ejaculation and separation from the seminal plasma. Other assays that directly detect sperm DNA (e.g., TUNEL assays, Comet assays, and acridine orange test) are not able to distinguish and detect the initial and potential DNA damage. Furthermore, the positive values in these direct assays are influenced by the frequency of immotile sperm and amorphous sperm populations.

Conclusion

The findings in the sperm chromosome assays show that further improvements in sperm preparation protocols may result in the reduction of sperm DNA damage, followed by more successful outcomes in infertility treatment.

Melittin-induced metabolic changes on the Madin-Darby Bovine Kidney cell line

ABSTRACT In this study, the toxic effects of melittin on Madin-Darby Bovine Kidney cells (MDBK) were analyzed with respect to mitochondrial functionality by reduction of MTT and flow cytometry, apoptosis potential, necrosis, oxygen reactive species (ROS) production, lipid peroxidation, and DNA fragmentation using flow cytometry and cell membrane destabilization by confocal microscopy. The toxicity presented dose-dependent characteristics and mitochondrial activity was inhibited by up to 78.24 ±3.59% (P<0.01, n = 6) in MDBK cells exposed to melittin (10μg/mL). Flow cytometry analysis revealed that melittin at 2μg/mL had the highest necrosis rate (P<0.05) for the cells. The lipoperoxidation of the membranes was also higher at 2μg/mL of melittin (P<0.05), which was further confirmed by the microphotographs obtained by confocal microscopy. The highest ROS production occurred when the cells were exposed to 2.5μg/mL melittin (P<0.05), and this concentration also increased DNA fragmentation (P<0.05). There was a significative and positive correlation between the lipoperoxidation of membranes with ROS (R=0.4158), mitochondrial functionality (R=0.4149), and apoptosis (R=0.4978). Thus, the oxidative stress generated by melittin culminates in the elevation of intracellular ROS that initiates a cascade of toxic events in MDBK cells.

Recovery of sperms bearing X chromosomes with different concentrations of magnetic nanoparticles in ram

Pre-conceptual sex selection is still a highly debatable process whereby X and Y chromosome bearing spermatozoa are isolated before oocyte fertilization. Recently, magnetic nanoparticles (MNP) have been used to determine X and Y chromosomes bearing spermatozoa as a result of searching for a cheap, highly efficient method using non-toxic materials. This study aimed to recover the sperm bearing X chromosomes in ram with different concentrations of MNP and then evaluate the success of this method using polymerase chain reaction (PCR). Ram sperms were divided into four groups, treated with 0 (control), 50, 100 and 200 μg/ml MNP, respectively. MNP was used to restore sperm cells bearing X chromosomes. Upon recovery, the PCR was performed to identify the X and Y sperms, Methyl ThiazoleTetrazolium (MTT), to assess MNP toxicity and sperm viability and acridine orange (AO) to evaluate sperm DNA integrity. The results of PCR revealed that the treatment of spermatozoa- bearing X chromosomes with 50 μg/ml MNP had the highest effects on the recovery of X sperm rather than the other concentrations of MNP. However, the concentrations of MNP did not have any toxic effects on spermatozoa, sperm viability and, DNA integrity, but the high concentration of MNP (200 μg/ml) significantly reduced DNA integrity. According to MTT and AO results, the concentrations of MNP used in this study had no toxic effects on spermatozoa and did not reduce the sperm viability and DNA integrity, except that 200 μg/ml MNP significantly reduced DNA integrity.

Apamin-induced alterations in J774 1.6 macrophage metabolism

ABSTRACT Among the immune system cells, macrophages have an important role. Apamin, a bee venom constituent, is important in the defense of these insects. Thus, we aimed to evaluate the metabolism of J774 1.6 macrophage cell line when exposed to isolated and purified apamin, using cytotoxicity tests by MTT reduction and analysis by flow cytometry (apoptosis / necrosis, production of reactive oxygen species (ROS), membranous lipoperoxidation (LPO), electrical potential of the mitochondrial membrane (mMP) and DNA fragmentation). None of the tested concentrations (10 to 100μg/mL) were cytotoxic according to MTT reductions. Apoptosis rates decreased at concentrations of 2.5, 5.0, and 10.0μg/mL (P<0.05), while necrosis rates increased (P<0.05). However, rates of healthy cells at the highest tested concentration (10μg/mL) did not differ from control (P>0.05). Apamin did not alter ROS, LPO, or DNA fragmentation. Therefore, all analyzed concentrations (1.25 to 10μg/mL) decreased mMP. Such decrease in apoptosis might be due to a suppression of mitochondrial pro-apoptotic messengers, as this peptide causes no oxidative stress, lipid peroxidation, and DNA damage. Highly sensitive techniques are majorly important for proper interpretation of cellular toxicity mechanisms, combined with routine laboratory methods.

In vivo acridine orange human spermatozoa staining-A new perspective for RNA detection and spermatozoa morphology evaluation

Significant increases in male infertility and the still unresolved questions on the compatibility and interpretation of current methods in infertility diagnostics call for new protocols. Morphology, genome damage, RNA content and quantity are currently in practice as the major parameters in evaluation of sperm quality. However, results of various methods are not always in mutual concordance. In this study, in vivo acridine orange (AO) staining, which is presently in application in the estimation of genome damage in reticulocytes, was adjusted for spermatozoa staining. Ten men suffering from oligoasthenoteratozoospermia (OAT) and 10 healthy fertile men were analysed using in vivo AO staining. Microscopic analysis was performed by fluorescent and confocal fluorescent microscopy. Our results show that this method preserves spermatozoa membranes, which enables new insight into spermatozoa genome damage, RNA content in residual cytoplasm, damage of neck area with mitochondrion and tail pathology. The introduced method explains the difference between results of sperm DNA fragmentation assay and the globally used AO staining and opens new options for the development of automated systems. In conclusion, the results of our study offer (a) an innovative approach to the analysis of spermatozoa pathology, (b) enable localization and quantification of RNA in residual cytoplasm, (c) a significant contribution to research of aetiology of infertility in men, (d) open new perspectives for the automatization of sperm quality estimation and (e) improve the personalized approach in the selection of in vitro fertilization protocols.

Comparative analysis of tests used to assess sperm chromatin integrity and DNA fragmentation

Male infertility has a complex etiology, and many times, the cause is unknown. While routine semen analysis provides an overview of basic semen parameters, such as sperm concentration, motility, viability and morphology, a significant overlap of these parameters has been reported in fertile and infertile men. Moreover, conventional semen parameters do not reveal the cellular or molecular mechanisms of sperm dysfunctions leading to infertility. Therefore, sperm functional parameters, including sperm chromatin integrity, are evaluated to provide information on subtle sperm defects that are not routinely identified. Incomplete or defective sperm chromatin condensation increases the susceptibility of the sperm DNA to oxidative damage or other factors. To evaluate sperm chromatin integrity, different methods with varying degrees of diagnostic and prognostic capabilities are available. Among these assays, SCSA, TUNEL and SCD assays are most commonly used. While these assays rather evaluate the DNA directly for damages, the aniline blue and chromomycin A3 stains test for the quality of chromatin condensation. Thus, this review discusses and compares different methods used to evaluate sperm chromatin integrity and condensation, and their inclusion in the routine evaluation of the male infertility.

Sperm DNA fragmentation index with unexplained recurrent spontaneous abortion: A systematic review and meta-analysis

BACKGROUND

A high sperm DNA fragmentation index (DFI) influences human reproduction and is observed in infertile men. However, the influence of DFI on unexplained recurrent spontaneous abortion (RSA) remains controversial.

OBJECTIVE

We explored the influence of DFI on unexplained recurrent spontaneous abortion.

DATA SOURCES

We conducted a meta-analysis of DFI (assessed by sperm chromatin structure assay(SCSA), terminal deoxynucleotidyl transferase-mediated deoxyuridine (TdT)triphosphate (dUTP) nick end labeling assay(TUNEL), sperm chromatin dispersion(SCD), single cell gel electrophoresis assay(COMET assay), and acridine orange test(AOT) with unexplained RSA from the Cochrane Library, EMBASE, Pubmed and Web of Science database.

METHODS

Records were screened for eligible studies and data were extracted to an online data extraction form. The main outcome was the sperm DFI. Summary measures were reported as the mean difference(MD) and Odds Ratio(OR) with 95 % confifidence interval (CI).

RESULT

We identified 27 articles including 3, 2, 9, 9, and 8 studies using AO, COMET, SCSA, SCD and TUNEL respectively; 7 articles used qualitative methods and 21 articles used in quantitative methods. The combined MD estimates of 7 SCSA studies (MD=5.4; 95 % CI: 1.76-9.03; P<0.01), 9 SCD studies (MD=11.16; 95 % CI:6.70-15.62; P<0.01), and 8 TUNEL studies (MD=12.12; 95 % CI: 3.34-20.91; P<0.01) showed significant differences. Notably, qualitative studies showed consistent results with quantitative studies.

CONCLUSION(S)

These findings support an association between sperm DFI and recurrent pregnancy loss. Previous studies revealed that DFI negatively impacts unexplained RSA.

Effects of temperature and storage time on the motility, viability, DNA integrity and apoptosis of processed human spermatozoa

The aim of this study was to evaluate motility, viability, DNA integrity and apoptosis of spermatozoa when washed semen samples were kept for up to 12 days at 4-6°C and 25°C. In this experimental study, 26 normozoospermic semen samples were washed twice in Modified Ham's F10 and resuspended in IVF fertilisation medium. Half of the specimens were stored at 4-6°C, and the other half was kept at 25°C for 12 days. The proportions of viable, motile, spermatozoa with double-stranded DNA and apoptotic spermatozoa were examined during storage time. Apoptosis was measured using annexin V-PI staining followed by flow cytometry. Results showed that sperm motility and viability decreased during 12 days of sample storage (p < .001). There was no significant difference between the two temperatures in terms of motility and viability for up to 2 days (p < .05). The percentage of spermatozoa with double-stranded DNA remained unchanged during the 12 days of storage at both temperatures (p > .05). Although there was no difference between the two temperatures in terms of motility, viability and apoptosis during the first two days of storage, storage of spermatozoa at 4-6°C is better than storage for a longer period than storage at 25°C. Sperm DNA resisted against denaturation during storage.

Impact of leukocytospermia on sperm dynamic motility parameters, DNA and chromosomal integrity

Introduction

To characterize sperm dynamic motility patterns and chromatin integrity in infertile men with leukocytospermia.

Material and methods

Fifty patients with primary infertility and oligoasthenoteratozoospermia included in this prospective, controlled, blind study. All patients underwent clinical evaluation, semen peroxidase stain, computer aided semen analysis (CASA), sperm DNA integrity evaluation with acridine orange test (AOT) and fluorescence in situ hybridization (FISH) analysis of 18, X and Y chromosomes. Pregnancy outcomes were documented following antibiotic treatment of patients with leukocytospermia.

Results

Infertile men with leukocytospermia had significantly lower progressive and total sperm motility percentages compared to the control group. Sperm dynamic motility parameters by CASA including curvilinear, straight line and average pathway velocities, straightness and amplitude of lateral head displacement were significantly lower in leukocytospermia. Sperm DNA fragmentation index was significantly higher in leukocytospermia. Percentages of sperm with disomy XY and 18 were significantly higher. These changes in sperm motility parameters and DNA integrity correlated with the number of peroxidase positive leukocytes. Follow-up of 23 of the 25 patients with leukocytospermia after antibiotic treatment revealed significantly higher pregnancy rates in cured patients than in those with persistent leukocytospermia.

Conclusions

Leukocytospermia has a significant impact on sperm dynamic motility patterns, DNA and chromosomal integrity in infertile men which can adversely affect the likelihood of a successful pregnancy.

Impact of a mild scrotal heating on sperm chromosomal abnormality, acrosin activity and seminal alpha-glucosidase in human fertile males

The aim of this study was to observe sperm aneuploidy, DNA integrity, seminal alpha-glucosidase (NAG) and acrosin activity (AA) under testicular heat stress (SH). Spermatozoa were obtained from 30 healthy adult volunteers subjected to scrotal warming at 43°C for 30-40 min on two successive days per week for 3 months between February 2012 and September 2016. Aniline blue (AB), acridine orange (AO) staining, TUNEL assay and FISH analysis to evaluate sperm function, sperm DNA integrity and chromosomal abnormalities were carried on before, during and after SH. Sperm AA and NAG was measured by microplate reader. The mean parameters of sperm parameters, AA and NAG were significantly decreased. In contrast, the mean percentage of sperm DNA fragmentation and the proportion of aneuploidy of chromosomes 13, 18, 21, X and Y were significantly increased for spermatozoa collected during SH versus before SH (p < .01-.001). After stopping scrotal heating for 3 months, most parameters were completely restored to pre-SH levels. Sperm parameters, sperm DNA integrity, chromosomes, AA and NAG are affected by scrotal exposure to constant SH temperatures several degrees over normal physiological temperature, and after treatment, these parameters were reversibly restored to the level before SH in adult men.

A systematic review on sperm DNA fragmentation in male factor infertility: Laboratory assessment

Objective

To review sperm DNA fragmentation (SDF) testing as an important sperm function test in addition to conventional semen analysis. High SDF is negatively associated with semen quality, the fertilisation process, embryo quality, and pregnancy outcome. Over recent decades, different SDF assays have been developed and reviewed extensively to assess their applicability and accuracy as advanced sperm function tests. Amongst them, the standardisation of the terminal deoxynucleotidyl transferased UTP nick-end labelling (TUNEL) assay with a bench top flow cytometer in clinical practice deserves special mention with a threshold value of 16.8% to differentiate infertile men with DNA damage from fertile men.

Materials and methods

A systematic literature search was performed through the PubMed, Medline, and ScienceDirect databases using the keywords ‘sperm DNA fragmentation’ and ‘laboratory assessment’. Non-English articles were excluded and studies related to humans were only included.

Results

Of the 618 identified, 87 studies (original research and reviews) and in addition eight book chapters meeting the selection criteria were included in this review. In all, 366 articles were rejected in the preliminary screening and a further 165 articles related to non-human subjects were excluded.

Conclusion

There are pros and cons to all the available SDF assays. TUNEL is a reliable technique with greater accuracy and as an additional diagnostic test in Andrology laboratories along with basic semen analysis can predict fertility outcome, and thus direct the choice of an assisted reproductive technology procedure for infertile couples. Also, the TUNEL assay can be used as a prognostic test and results are beneficial in deciding personalised treatment for infertile men.

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% CI: 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% CI: 1.08–1.59; P = 0.0068), and mixed IVF + ICSI studies (16 estimates, OR = 2.37; 95% CI: 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.

Measuring Sperm DNA Fragmentation and Clinical Outcomes of Medically Assisted Reproduction: A Systematic Review and Meta-Analysis

Sperm DNA fragmentation has been associated with reduced fertilization rates, embryo quality, pregnancy rates and increased miscarriage rates. Various methods exist to test sperm DNA fragmentation such as the sperm chromatin structure assay (SCSA), the sperm chromatin dispersion (SCD) test, the terminal deoxynucleotidyl transferase mediated deoxyuridine triphosphate nick end labelling (TUNEL) assay and the single cell gel electrophoresis (Comet) assay. We performed a systematic review and meta-analysis to assess the value of measuring sperm DNA fragmentation in predicting chance of ongoing pregnancy with IVF or ICSI. Out of 658 unique studies, 30 had extractable data and were thus included in the meta-analysis. Overall, the sperm DNA fragmentation tests had a reasonable to good sensitivity. A wide variety of other factors may also affect the IVF/ICSI outcome, reflected by limited to very low specificity. The constructed hierarchical summary receiver operating characteristic (HSROC) curve indicated a fair discriminatory capacity of the TUNEL assay (area under the curve (AUC) of 0.71; 95% CI 0.66 to 0.74) and Comet assay (AUC of 0.73; 95% CI 0.19 to 0.97). The SCSA and the SCD test had poor predictive capacity. Importantly, for the TUNEL assay, SCD test and Comet assay, meta-regression showed no differences in predictive value between IVF and ICSI. For the SCSA meta-regression indicated the predictive values for IVF and ICSI were different. The present review suggests that current sperm DNA fragmentation tests have limited capacity to predict the chance of pregnancy in the context of MAR. Furthermore, sperm DNA fragmentation tests have little or no difference in predictive value between IVF and ICSI. At this moment, there is insufficient evidence to recommend the routine use of sperm DNA fragmentation tests in couples undergoing MAR both for the prediction of pregnancy and for the choice of treatment. Given the significant limitations of the evidence and the methodological weakness and design of the included studies, we do urge for further research on the predictive value of sperm DNA fragmentation for the chance of pregnancy after MAR, also in comparison with other predictors of pregnancy after MAR.

Target Delivery of a Novel Antitumor Organoplatinum(IV)-Substituted Polyoxometalate Complex for Safer and More Effective Colorectal Cancer Therapy In Vivo

An inactive organoplatinum(IV)-substituted polyoxometalate is developed as an efficient and nontoxic prodrug with significant potential for treating human colorectal cancers. Further encapsulation of Pt(IV) -PW11 with DSPE-PEG2000 nanoparticles (NPs) enables targeted delivery and controlled release of inactive prodrug. Such Pt(IV) -PW11 -DSPE-PEG2000 NPs are highly efficient in inhibiting cellular growth of HT29 cells and treating human colorectal cancer in mice, superior to classic cisplatin.

Acridine Orange and Flow Cytometry: Which Is Better to Measure the Effect of Varicocele on Sperm DNA Integrity?

We evaluated the effect of varicocelectomy on semen parameters and levels of sperm DNA damage in infertile men. A total of 75 infertile men with varicocele and 40 fertile men (controls) were included in this study. Semen analysis and sperm DNA damage expressed as the DNA fragmentation index using acridine orange staining and chromatin condensation test by flow cytometry were assessed before and 6 months after varicocelectomy. The patients were also followed up for 1 year for pregnancy outcome. Semen parameters were significantly lower in varicocele patients compared to controls (P < 0.05). Mean percentages of sperm DNA fragmentation and sperm DNA chromatin condensation in patients were significantly higher than those in controls (P < 0.05). After varicocelectomy, sperm DNA fragmentation improved significantly, whereas sperm chromatin condensation was not significantly changed. In 15 out of 75 varicocele patients, clinical pregnancy was diagnosed; those with positive pregnancy outcome had significant improvement in sperm count, progressive sperm motility, and sperm DNA fragmentation, but there was no significant difference in sperm DNA condensation compared to negative pregnancy outcome patients. We concluded from this study that acridine orange stain is more reliable method than flow cytometry in the evaluation of sperm DNA integrity after varicocelectomy.

Does varicocelectomy affect DNA fragmentation in infertile patients?

Introduction:

The aims of this study were to investigate the effect of varicocelectomy on DNA fragmentation index and semen parameters in infertile patients before and after surgical repair of varicocele.

Materials and Methods:

In this prospective study, 72 men with at least 1-year history of infertility, varicocele and oligospermia were examined. Varicocele sperm samples were classified as normal or pathological according to the 2010 World Health Organization guidelines. The acridine orange test was used to assess the DNA fragmentation index (DFI) preoperatively and postoperatively.

Results:

DFI decreased significantly after varicocelectomy from 34.5% to 28.2% (P = 0.024). In addition all sperm parameters such as mean sperm count, sperm concentration, progressive motility and sperm morphology significantly increased from 19.5 × 10⁶ to 30.7 × 10⁶, 5.4 × 10⁶/ml to 14.3 × 10⁶/ml, and 19.9% to 31.2% (P < 0.001) and 2.6% to 3.1% (P = 0.017). The study was limited by the loss to follow-up of some patients and unrecorded pregnancy outcome due to short follow-up.

Conclusion:

Varicocele causes DNA-damage in spermatozoa. We suggest that varicocelectomy improves sperm parameters and decreases DFI.

Impact of sperm chromatin evaluation on fertilization rate in intracytoplasmic sperm injection

BACKGROUND

Sperm DNA in human beings and most vertebrates is packed by protamines into highly compact form of chromatin. There are many staining methods to assess sperm chromatin. Three different methods of staining were used simultaneously in this study and the goal was to determine which of these sperm tests has a relation with fertilization rate in intracytoplasmic sperm injection (ICSI).

MATERIALS AND METHODS

Thirty couples who referred to Yamagata University Hospital (Yamagata, Japan) for ICSI were included in this study. The greater part of semen was prepared for ICSI. The remaining part was used for staining with aniline blue, acridine orange, and chromomycin A3 (CMA3). For evaluation of abnormal morphology and abnormality of head, Papanicolaou-stained smears were used. The analysis of data was done using Spearman coefficient of correlation and logistic regression model. Receiver operator characteristic (ROC) curve was used for discrimination of CMA3 staining power to identify ICSI rates.

RESULTS

Percentage of CMA3 positivity, unlike those of aniline blue and acridine orange, showed significant negative correlation with fertilization rate. Moreover, the percentage of CMA3 positivity showed a positive correlation with the percentage of abnormal morphology and abnormality of head. By dividing patients into CMA3 <48% and CMA3> 48% groups, the area under the curve was 0.646.

CONCLUSIONS

CMA3 staining (protamine deficiency) could be considered as a useful tool for evaluation of male fertility prior to infertility treatment.

Potential Health Risks Associated to ICSI: Insights from Animal Models and Strategies for a Safe Procedure

Artificial reproductive techniques are currently responsible for 1.7–4% of the births in developed countries and intracytoplasmatic sperm injection (ICSI) is the most commonly used, accounting for 70–80% of the cycles performed. Despite being an invaluable tool for infertile couples, the technique bypasses several biological barriers that naturally select the gametes to achieve an optimal embryonic and fetal development. In this perspective, ICSI has been associated with an increased risk for diverse health problems, ranging from premature births and diverse metabolic disorders in the offspring to more severe complications such as abortions, congenital malformations, and imprinting disorders. In this review, we discuss the possible implications of the technique per se on these adverse outcomes and highlight the importance of several experiments using mammalian models to truthfully test these implications and to uncover the molecular base that origins these health problems. We also dissect the specific hazards associated to ICSI and describe some strategies that have been developed to mimic the gamete selection occurring in natural conception in order to improve the safety of the procedure.

Sperm preparation before freezing improves sperm motility and reduces apoptosis in post-freezing-thawing sperm compared with post-thawing sperm preparation

PURPOSE

To evaluate whether sperm preparation (swim-up technique) before freezing improves the percentages of sperm motility, sperm viability, and non-apoptotic spermatozoa after freezing-thawing process compared with preparation after cryopreservation.

METHODS

Semen samples from 65 infertile males were equally divided into two aliquots one of which was processed for swim-up prior to cryopreservation and one of which was processed following cryopreservation. Sperm count, motility, and apoptosis index were measured in each group.

RESULT (S)

The total sperm count and the total motile sperm count decreased after thawing in both the pre-preparation and non-preparation groups compared with neat semen group (P < 0.001). Moreover, the percentage of apoptotic sperm in the pre-preparation group after cryopreservation was lower than that in the non-preparation group (P < 0.05), whereas the percentage of vital sperm with progressive motility was higher than that in the pre-preparation group (P < 0.001).

CONCLUSION (S)

Semen preparation by swim-up before freezing resulted in better sperm quality and fewer apoptotic sperm than sperm preparation after thawing. Therefore, sperm preparation before cryopreservation should be considered in routine sperm cryopreservation.

Small-volume vitrification for human spermatozoa in the absence of cryoprotectants by using Cryotop

Cryotop is a carrier that has been used successfully in the cryopreservation of human spermatozoa. Here, we explored a novel method to vitrify human spermatozoa without cryoprotective agents (CPAs) using Cryotop. Spermatozoa from 21 Normozoospermic patients were collected and vitrified without CPAs or with sucrose in small volume using Cryotop. The sperm recovery rate, motility, viability, chromatin damage and DNA fragmentation were assessed. No significant difference was observed in the sperm recovery rate and motility rate between the spermatozoa cryopreserved without CPAs and with sucrose. The post-thawed spermatozoa cryopreserved without CPAs had a higher viability and lower damage to sperm chromatin and DNA than those cryopreserved with sucrose. These results suggest that small numbers of human spermatozoa can be successfully vitrified without CPAs using Cryotop.

Does centrifugation and semen processing with swim up at 37°C yield sperm with better DNA integrity compared to centrifugation and processing at room temperature?

AIM:

To evaluate whether semen processing at 37°C yield sperm with better DNA integrity compared to centrifugation and processing at room temperature (RT) by swim-up method.

SETTINGS:

This study was done at tertiary care center attached to Reproductive Medicine Unit and Medical College.

DESIGN:

Prospective pilot study.

PATIENTS:

Normozoospermic men (n = 50) undergoing diagnostic semen analysis.

MATERIALS AND METHODS:

Normozoospermic samples (World Health Organization, 2010 criteria) after analysis was divided into two aliquots (0.5 mL each); one was processed at 37°C and the other at RT by swim-up method. DNA fragmentation of both samples post wash was calculated by acridine orange method.

STATISTICAL ANALYSIS USED:

The values of sperm DNA fragmentation were represented as mean and standard error (mean ± SEM) of the mean. Paired t-test was used for calculating the sperm DNA integrity difference between post wash at RT and 37°C.

RESULTS:

Statistically significant difference was not observed in post wash sperm DNA fragmentation values at 37°C compared to RT.

CONCLUSION:

Our data represents that there was no significant difference in sperm DNA fragmentation values of samples processed at 37°C and at RT. Hence, sperm processing at 37°C does not yield sperm with better DNA integrity compared to centrifugation and processing at RT.

Sperm chromatin condensation, DNA integrity, and apoptosis in men with spinal cord injury

OBJECTIVES

To evaluate the effect of cord injury on (1) sperm parameters and (2) DNA chromatin status.

DESIGN

Case-control study.

SETTING

Data were collected from men referred to Research and Clinical Center for Infertility, Yazd, Iran.

PARTICIPANTS

Thirty infertile men with the presence of any level of spinal cord injury (SCI) were compared with 30 healthy donors with definite fertility and normal sperm parameters.

INTERVENTIONS

Not applicable.

OUTCOME MEASURES

Sperm chromatin integrity was assessed using aniline blue (AB), chromomycin A3 (CMA3), toluidine blue (TB), and acridine orange (AO) assays. The rate of apoptotic spermatozoa was evaluated with terminal deoxynucleotidyl transferase-mediated dUTP nick-end labelling (TUNEL) staining.

RESULTS

Sperm concentration, motility, and morphology in men with SCI were significantly decreased compared with control group (P < 0.05). In addition, with regard to cytochemical staining and TUNEL test, the rate of reacted spermatozoa was increased significantly in SCI group when compared with the controls (P < 0.05). The majority of AB, TB, AO, and CMA3-reacted spermatozoa were higher than the "cut-off" value in men with SCI, as were the number of apoptotic spermatozoa stained with TUNEL.

CONCLUSION

Results showed that SCI disturbs sperm parameters, nuclear maturity, and DNA integrity of spermatozoa. Therefore, the production of spermatozoa with less condensed chromatin and more apoptotic rate increases after cord injury and this may be one possible cause of infertility following SCI.

Sperm flow cytometric parameters are associated with ICSI outcome

The association of sperm nuclear chromatin condensation and ploidy with embryo development and outcome after intracytoplasmic sperm injection (ICSI) was explored. The study population consisted of 16 couples referred to Ioannina University Medical School In vitro Fertilization Unit with male factor infertility and serious impairments in sperm nuclear chromatin condensation and ploidy, according to sperm flow cytometry. Additionally, 20 couples with male factor infertility and relatively high sperm flow cytometry parameters participated as controls. The 35 cycles of the study population were characterized by a lower fertilization rate (P<0.001) as well as decreased grade A embryo rate (P=0.004) and increased grade C embryo rate (P=0.028), compared with the 29 cycles of the control group. Additionally, a significantly elevated arrested embryo rate (P<0.001) and a decreased clinical pregnancy rate (P<0.020) were observed in the couples of the study population. Consequently, high levels of sperm nuclear chromatin condensation abnormalities and sperm aneuploidies are probably associated with lower fertilization rates, impaired embryo quality, elevated arrested embryo rates and decreased pregnancy rates. These preliminary results strongly support the use of sperm flow cytometry as a potential prognostic tool of ICSI outcome.

Assessment of sperm chromatin condensation and ploidy status using flow cytometry correlates to fertilization, embryo quality and pregnancy following in vitro fertilization

PURPOSE

Sperm flow cytometry (SFC) was used to evaluate the association of sperm chromatin condensation and ploidy with fertilization, embryo development, pregnancy and abortion rates following IVF.

METHODS

Conventional semen analysis was performed in one hundred fifty men, as well as SFC analysis, after acridine orange and propidium iodide staining, for the evaluation of sperm maturity and ploidy respectively. Conventional IVF was performed in all couples.

RESULTS

Couples with low percentages of mature spermatozoa presented with lower fertilization rates (p < 0.005), lower rates of grade A embryos (p < 0.003) and lower pregnancy rates (p < 0.006), compared to couples with high percentages of mature spermatozoa. Couples with low total aneuploidy rates presented with higher fertilization rates (p < 0.007), higher rates of grade A embryos (p < 0.004) and higher pregnancy rates (p < 0.003), compared to couples with high total aneuploidy rates.

CONCLUSIONS

Sperm chromatin condensation and ploidy constitute critical parameters for the evaluation of semen samples before IVF and for the identification of cases in need of ICSI application.

Effects of ethanol consumption on chromatin condensation and DNA integrity of epididymal spermatozoa in rat

Alcohol abuse is considered as one of the problems associated with poor semen production and sperm quality. Both acute and chronic alcohol consumption may affect spermatozoal chromatin disorders through apoptosis. Therefore, for the first time, this experimental study was performed to evaluate the effect of ethanol consumption on sperm parameters and chromatin integrity of spermatozoa aspirated from cauda epididymis of rats. Twenty adult Wistar rats were divided into ethanol consumption and control groups. Access to ethanol and water was provided ad libitum for experimental and control animals, respectively. The cauda epididymal spermatozoa were aspirated for analysis of sperm parameters and sperm chromatin integrity with aniline blue (AB), chromomycin A3 (CMA3), toluidine blue (TB), and acridine orange (AO) assays. Sperm progressive and nonprogressive motility of ethanol-consuming rats were significantly decreased compared with control animals (P < .05). In addition, the rates of AB-reacted spermatozoa were similar in both groups (P > .05). However, with regard to CMA3, AO, and TB stainings, there was a significant increase in ethanol group when compared with the controls (P < .05). The majority of TB+ and AO+ spermatozoa were higher than "cut-off" value in ethanol group, whereas the mean rates of CMA3+ spermatozoa was below the "cut-off" value in both groups. The results showed that ethanol consumption disturbs sperm motility, nuclear maturity and DNA integrity of spermatozoa in rat. Therefore, ethanol abuse results in the production of spermatozoa with less condensed chromatin, and this may be one possible cause of infertility following ethanol consumption.

DNA sperm damage correlates with nuclear ultrastructural sperm defects in teratozoospermic men

Sperm morphology has consistently been the best indicator of male fertility. Transmission electron microscopy currently provides the most information on the subcellular details of sperm structure. Recently, assessment of sperm DNA damage has been employed to assess fertility potential. The purpose of this work was to link sperm DNA damage, evaluated by an intercalated fluorescent dye, with the structural characteristics of sperm. Conventional semen analysis was performed on samples from men undergoing fertility evaluation. Thirty men were evaluated and assigned to three subgroups based on strict criteria for sperm morphology: normal morphology (>14% normal forms), intermediate morphology (5-14% normal forms), and poor morphology (<5% normal forms). By quantifying acridine orange-positive cells and ultrastructural sperm defects, we found that the poor morphology pattern group showed a positive association between sperm carrying damaged DNA and the percentage of sperm nucleus with vacuoles (P = 0.01). No statistically significant correlations were established in other ultrastructural characteristics of sperm, including immature chromatin, lytic changes, or abnormal sperm tails. These results suggest that zones without chromatin in the sperm nucleus reflect underlying chromosomal or DNA defects in severe teratozoospermic men. This association should be considered in the evaluation of male fertility.

Sperm chromatin condensation in infertile men with varicocele before and after surgical repair

OBJECTIVE

To assess sperm chromatin integrity in infertile men with varicocele before and after surgical repair.

DESIGN

Prospective.

SETTING

Academic setting.

PATIENT(S)

Seventy-two infertile men with varicocele compared with 20 healthy fertile men.

INTERVENTION(S)

History taking, genital examination, semen analysis, sperm chromatin condensation assessment by aniline blue stain before and 3 months after varicocelectomy.

MAIN OUTCOME MEASURE(S)

Stained sperm heads (abnormal chromatin condensation) before and 3 months after varicocelectomy.

RESULT(S)

The mean percentage of aniline blue-stained sperm heads was significantly higher in infertile men with varicocele compared with fertile controls. The mean percentage of stained sperm heads was significantly decreased in infertile men with varicocele 3 months after surgery compared with the preoperative data. There was a significant negative correlation between percentage of stained sperm heads and normal morphology where nonsignificant correlation was elicited regarding sperm count and sperm motility.

CONCLUSION(S)

There is a significant increase of abnormal sperm chromatin condensation in infertile men with varicocele that is markedly improved after varicocelectomy.

An assessment of new sperm tests for male infertility

The routine semen analysis, although used for more than 50 years, fails to accurately distinguish between fertile and infertile men. As a consequence, many tests of sperm function (TSF) have been developed. This review discusses both older and newer diagnostic TSF. It outlines the principles underlying each assay and reviews aggregate clinical data to determine its current relevance and utility. It concludes that the relevance of many older TSF is questionable, with the wide acceptance of intracytoplasmic sperm injection (ICSI). Newer TSF have the potential to deliver more clinically relevant information but require more extensive study to better understand their predictive role in the ICSI era.

Selection against spermatozoa with fragmented DNA after postovulatory mating depends on the type of damage

BACKGROUND

Before ovulation, sperm-oviduct interaction mechanisms may act as checkpoint for the selection of fertilizing spermatozoa in mammals. Postovulatory mating does not allow the sperm to attach to the oviduct, and spermatozoa may only undergo some selection processes during the transport through the female reproductive tract and/or during the zona pellucida (ZP) binding/penetration.

METHODS

We have induced DNA damage in spermatozoa by two treatments, (a) a scrotal heat treatment (42 degrees C, 30 min) and (b) irradiation with 137Cs gamma-rays (4 Gy, 1.25 Gy/min). The effects of the treatments were analyzed 21-25 days post heat stress or gamma-radiation. Postovulatory females mated either with treated or control males were sacrificed at Day 14 of pregnancy, and numbers of fetuses and resorptions were recorded.

RESULTS

Both treatments decreased significantly implantation rates however, the proportion of fetuses/resorptions was only reduced in those females mated to males exposed to radiation, indicating a selection favoring fertilization of sperm with unfragmented DNA on the heat treatment group. To determine if DNA integrity is one of the keys of spermatozoa selection after postovulatory mating, we analyzed sperm DNA fragmentation by COMET assay in: a) sperm recovered from mouse epididymides; b) sperm recovered from three different regions of female uterine horns after mating; and c) sperm attached to the ZP after in vitro fertilization (IVF). Similar results were found for control and both treatments, COMET values decreased significantly during the transit from the uterine section close to the uterotubal junction to the oviduct, and in the spermatozoa attached to ZP. However, fertilization by IVF and intracytoplasmatic sperm injection (ICSI) showed that during sperm ZP-penetration, a stringent selection against fragmented-DNA sperm is carried out when the damage was induced by heat stress, but not when DNA fragmentation was induced by radiation.

CONCLUSION

Our results indicate that in postovulatory mating there is a preliminary general selection mechanism against spermatozoa with low motility and fragmented-DNA during the transport through the female reproductive tract and in the ZP binding, but the ability of the ZP to prevent fertilization by fragmented-DNA spermatozoa is achieved during sperm-ZP penetration, and depends on the source of damage.

Embryo development after intracytoplasmic sperm injection can be predicted by assessment of sperm nuclear chromatin

Purpose

To assess the influence of structural differences in sperm nuclei on embryo development in intracytoplasmic sperm injection (ICSI).

Methods

Semen obtained from forty-four infertile patients who underwent ICSI was examined. In assessing blastocyst development, only those patients who had successfully obtained over five fertilized eggs were included to exclude any oocyte factors (n = 22). Spermatozoa were assessed using excitation fluorescence flow cytometry with acridine orange and the sperm chromatin dispersion (SCD) test.

Results

There was a significant positive correlation between the COMP values obtained from flow cytometry and blastocyst formation. (r = 0.477, p = 0.025). There was a significant negative correlation between the SCD values representing DNA fragmentation and blastocyst formation. (r = 0.796, p < 0.001). COMP values and SCD values were independent parameters to assess sperm nuclear quality regarding embryo development in vitro (r = 0.224, p = 0.080).

Conclusion

Results suggest that injection of spermatozoa with fewer disulfide bonds and less nuclear DNA fragmentation could achieve better blastocyst formation in human ICSI. Assessment of sperm chromatin should help to predict embryo development after ICSI.

Markers of oxidative stress and sperm chromatin integrity

Oxidative stress (OS) is an imbalance between the amount of reactive oxygen species (ROS) produced and the ability of the antioxidants to scavenge these. OS has been established as a major etiological cause of male infertility. High levels of ROS are harmful and cause damage to sperm nuclear DNA. Evaluation of OS-related damage to spermatozoa is therefore highly relevant in assisted reproductive techniques (ART) such as intracytoplasmic sperm injection (ICSI). ICSI is an effective therapy for severe male factor infertility that bypasses the majority of reproductive tract deficiencies. Despite the controversial findings in the existing literature, there is now enough evidence to show that sperm DNA damage is detrimental to reproductive outcomes. In addition to impairment of fertility, such damage might increase the transmission of genetic diseases to the offspring. Standardization of protocols to assess ROS, antioxidant status, and DNA damage is very important for implementation of these tests in clinical practice. Estimation of seminal ROS levels and extent of sperm DNA damage, especially in an infertile male, may help develop new therapeutic strategies and improve the success of ART.

Hypothyroidism has an adverse effect on human spermatogenesis: a prospective, controlled study

BACKGROUND

Abnormalities of spermatogenesis are associated with numerous diseases and aging. The objective of this study was to investigate the impact of hypothyroidism on human spermatogenesis and different sperm function tests.

METHODS

Twenty-five hypothyroid men and 15 normal individuals were investigated. Semen analysis, fructose and acid phosphatase measurements, teratozoospermia index (TZI), and acridine orange test were determined before and 6-9 months after the initiation of treatment with levothyroxine.

RESULTS

Morphology is the only sperm parameter that differs significantly between hypothyroid patients and controls (p < 0.0001). After treatment, morphology improved significantly (p < 0.001). Motility was also decreased before treatment in comparison with controls, and improved after treatment. However, the difference was not significant. TZI correlated with free thyroxine.

CONCLUSIONS

Hypothyroidism has an adverse effect on human spermatogenesis. Morphology is the only sperm parameter that is significantly affected. Motility may also be affected, but further studies regarding this are needed. Screening for thyroid dysfunction in males who present with a defect in spermatogenesis is strongly recommended, and if hypothyroidism is noted, the response to thyroid hormone should be evaluated before initiating other treatments.

Association of various sperm parameters with unexplained repeated early pregnancy loss--which is most important?

OBJECTIVES

To study the relationship of various sperm characteristics with repeated unexplained early pregnancy loss.

BASIC PROCEDURE

Semen samples from husbands of 74 couples with the history of repeated early pregnancy loss were analyzed as per WHO criteria, and DNA integrity was studied in each case by Acridine Orange staining test. Semen samples from 65 husbands of proven fertility were also studied for comparison.

MAIN FINDINGS

No statistically significant differences were noted in the age of the husbands, sperm concentration, total count per ejaculate, and rapid progressive motility of sperms between the two groups. On the other hand, significant differences were found in total motile sperms per ejaculate, percentage of motile sperm and, most importantly, in the DNA integrity value.

CONCLUSION

The sperm DNA-integrity damage is an important paternal factor associated with repeated embryonic or early fetal loss and should be included in the evaluation of these couples.

Significance of large nuclear vacuoles in human spermatozoa: implications for ICSI

The aim of this study was to determine the extent of DNA fragmentation and the presence of denatured single-stranded or normal double-stranded DNA in spermatozoa with large nuclear vacuoles (LNV) selected by high magnification. Fresh semen samples from 30 patients were prepared by discontinuous isolate concentration gradient. Spermatozoa with normal nucleus (NN) and LNV were selected at x8400 magnification and placed on different slides. DNA fragmentation was determined by TUNEL assay. Denatured and double-stranded DNA was identified by the acridine orange fluorescence method. DNA fragmentation in spermatozoa with LNV (29.1%) was significantly higher (P < 0.001) than in spermatozoa with NN (15.9%). Therefore, cleavage of genomic DNA in low molecular weight DNA fragments (mono- and oligonucleosomes), and single-strand breaks (nicks) in high molecular weight DNA occur more frequently in spermatozoa with LNV. Similarly, the percentage of denatured-stranded DNA in spermatozoa with LNV (67.9%) was significantly higher (P < 0.0001) than in spermatozoa with NN (33.1%). The high level of denatured DNA in spermatozoa with LNV suggests precocious decondensation and disaggregation of sperm chromatin fibres. The results show an association between LNV and DNA damage in spermatozoa, and support the routine morphological selection and injection of motile spermatozoa at high magnification for ICSI.

Factors affecting chromatin stability of bovine spermatozoa

The structural stability of transcriptionally inert paternal chromatin is of vital importance for the fertilization process and early embryonic development. Accordingly, a series of eight experiments were conducted during a 7-month period to investigate: (1) effects of bull breed, individuality, successive ejaculations, semen quality characteristics (SQC), semen dilution rates and hypothermic storage of semen in a Tris-egg yolk extender on incidence of sperm nuclear chromatin instability (NCI), and (2) effects of the interaction between variation of NCI within a frozen ejaculate and variation of oocytes quality due to maturation time and/or season on the efficiency of in vitro embryo production (IVEP). Semen samples were collected once a week from six bulls using an AV and only ejaculates (n=220) of >0.30x10(9) sperm/ml and >or=60% motility were used. NCI was measured by: (1) detection of lysine-rich histones in sperm chromatin using aniline blue staining, (2) sperm susceptibility to acid-induced nuclear DNA denaturation in situ using acridine orange test, and (3) sperm susceptibility to nuclear chromatin decondensation (NCD). Bovine oocytes (n=695) were matured in vitro for 18 or 24 h, fertilized after sperm selection through a swim-up procedure and cultured for 72 h. The results showed that the 2nd ejaculates were superior to the 1st ones with respect to chromatin stability. Dilution of semen to 49.67+/-8.56x10(6) sperm/ml (1:19) decreased resistance of sperm to NCD. Cooling of semen had no significant effect on chromatin stability. Cryopreservation of semen augmented sperm vulnerability to DNA denaturation. Improvement of SQC (semen volume, sperm motility, velocity, viability and morphological normalcy) was generally concomitant with increase of sperm resistance to NCI. While Blonde d'Aquitaine bulls had a resistance to NCD higher than Limousine bulls in fresh semen, the former showed a greater susceptibility to DNA denaturation than the latter in cooled semen. Individuality significantly influenced NCI. The variability of NCI within a frozen ejaculate affected efficiency of IVEP. Significant negative correlations were observed between incidence of NCI and both fertilization rate and developmental capacity of embryos after maturation of oocytes for 18 h. The significant variation in IVEP traits due to season was independent of the effect of sperm chromatin instability.

Mammalian sperm chromatin structure and assessment of DNA fragmentation

This review article illustrates the biology of mammalian sperm chromatin structure. The possible causes of DNA (deoxyribonucleic acid) fragmentation are discussed. Also available molecular techniques for assessment of mammalian sperm DNA damage are described.

[Assessing sperm DNA damage]

Infertility affects almost 20% of couples in reproductive age and the male factor being responsible of 50% of this infertility. Among the classic parameters that determine a good seminal quality such as sperm motility, sperm morphology or the quality of the of acrosomes and/or sperm membranes, the integrity of the DNA molecule is crucial to carry out a successful fertilization. Nevertheless, the study of this parameter has not been straightforward approached. This fact has shunned its incorporation, as a routine technique, within a standard seminogram. The aim of the present review is to summarize and update those technologies that are considered more successful to study sperm DNA fragmentation with special emphasis to: 1) the levels of technological complexity and the possibility of its use in laboratories of andrology, according with the equipment and the resources available, and 2) the effects and possible implications of high level of sperm DNA fragmentation for fecundation, embryo development and fertility.