Effects of short and long incubations on DNA fragmentation of testicular sperm

Quality of testicular spermatozoa improves with changes in composition of culture medium

BACKGROUND

Spermatozoa retrieved from the testis and epididymis are deprived of the beneficial effects of seminal fluid. Thus applying an artificial medium with normal seminal fluid characteristics, known as artificial seminal fluid (ASF), may provide an appropriate condition for improving some sperm parameters in azoospermia. The objective was to investigate the impact of in vitro exposure of testicular and epididymal spermatozoa to ASF on sperm quality. The study was conducted on testicular (n = 20) and epididymal (n = 20) sperm specimens obtained from azoospermic men. Each sample was divided into two equal parts: Part I) for processing and incubation with Ham's F10 medium; Part II) for processing and incubation with ASF.

RESULTS

After 2 h incubation, testicular sperm motility was significantly higher in ASF than in Ham's F10 medium. In comparison to 0 h, mitochondrial membrane potential levels of testicular spermatozoa were significantly higher after 2 h and 24 h in ASF and after 24 h in Ham's F10 medium. Furthermore, the data indicated significantly lower rates of epididymal spermatozoa with high MMP in both media after 24 h. There were no significant differences in the DNA fragmentation index of testicular and epididymal spermatozoa between ASF and Ham's F10 medium at different time points.

CONCLUSION

The results demonstrated that in vitro incubation of testicular spermatozoa improved their motility more effectively than Ham's F10 medium in the short term (2 h), but had no effect on epididymal spermatozoa. Since the physiology of testicular spermatozoa is different from that of ejaculated spermatozoa, it seems that a special environment should be designed and used for each of them.

Embryo development and live birth resulted from artificial oocyte activation after microdissection testicular sperm extraction with ICSI in patients with non-obstructive azoospermia

INTRODUCTION

The application of microdissection testicular sperm extraction (micro-TESE) to retrieve the sperm of patients with non-obstructive azoospermia (NOA) has greatly increased. Patients with NOA often have poor quality sperm. Unfortunately, there are few studies on artificial oocyte activation (AOA) performed on patients who successfully retrieved motile and immotile sperm by micro-TESE after intracytoplasmic sperm injection (ICSI). Therefore, this study sought to obtain more comprehensive evidence-based data and embryo development outcomes to aid consultation of patients with NOA who opted to receive assisted reproductive techniques and to determine whether AOA needs to be performed in different motile sperm after ICSI.

METHODS

This retrospective study involved 235 patients with NOA who underwent micro-TESE to retrieve adequate sperm for ICSI between January 2018 and December 2020. A total of 331 ICSI cycles were performed in the 235 couples. Embryological, clinical, and neonatal outcomes were demonstrated comprehensively between motile sperm and immotile sperm using AOA and non-AOA treatment.

RESULTS

Motile sperm injection with AOA (group 1) showed significantly higher fertility rate (72.77% vs. 67.59%, p=0.005), 2 pronucleus (2PN) fertility rate (64.33% vs. 60.22%, p=0.036), and miscarriage rate (17.65% vs. 2.44%, p=0.018) compared with motile sperm injection with non-AOA (group 2). Group 1 had comparable available embryo rate (41.29% vs. 40.74%, p=0.817), good embryo rate (13.44% vs. 15.44%, p=0.265), and without an embryo for transfer rate (10.85% vs. 9.90%, p=0.815) compared with group 2. Immotile sperm injection with AOA (group 3) displayed significantly higher fertility rate (78.56% vs. 67.59%, p=0.000), 2PN fertility rate (67.36% vs. 60.22%, p=0.001), without an embryo for transfer rate (23.76% vs. 9.90%, p=0.008), and miscarriage rate (20.00% vs. 2.44%, p=0.014), but significantly lower available embryo rate (26.63% vs.40.74%, p=0.000) and good embryo rate (15.44% vs. 6.99%, p=0.000) compared with group 2. In groups 1, 2, and 3, the rates of implantation (34.87%, 31.85% and 28.00%, respectively; p=0.408), clinical pregnancy (43.87%, 41.00%, and 34.48%, respectively; p=0.360) and live birth (36.13%, 40.00%, and 27.59%, respectively; p=0.194) were similar.

DISCUSSION

For those patients with NOA from whom adequate sperm were retrieved for ICSI, AOA could improve fertilization rate, but not embryo quality and live birth outcomes. For patients with NOA and only immotile sperm, AOA can help achieve acceptable fertilization rate and live birth outcomes. AOA is recommended for patients with NOA only when immotile sperm are injected.

How does sperm apoptosis affect the outcome of intrauterine insemination and intracytoplasmic sperm injection?

Up to 20% of male infertility is caused by abnormal DNA organization of the sperm and anomalies of the sperm apoptosis. The aim of this study was to investigate the sperm DNA apoptosis and viability in patients undergoing intrauterine insemination (IUI) and intracytoplasmic sperm injection (ICSI). In the second part of the analysis, sperm DNA apoptosis and viability were investigated in patients with oligozoospermia and normospermia respectively. A total of 45 IUI and 38 ICSI patients were included in this study. Annexin V analysis was performed to investigate the sperm viability, and TUNEL assay was used to evaluate the sperm DNA apoptosis. Further investigations using 12 oligozoospermia and 11 control samples for sperm viability and sperm DNA apoptosis at different incubation periods and temperatures were performed. The results of this study showed a negative correlation between the sperm DNA apoptosis in IUI patients, but no relationship was observed for the ICSI patients. The second part of this study showed that incubation of semen samples at 37°C for 3 h has detrimental effects on the sperm DNA integrity. In conclusion, the incubation of semen at high temperatures affects the sperm quality. The results of this study showed that these tests can be beneficial for the infertile couples to achieve pregnancy.

DNA damage in preimplantation embryos and gametes: specification, clinical relevance and repair strategies

BACKGROUND

DNA damage is a hazard that affects all cells of the body. DNA-damage repair (DDR) mechanisms are in place to repair damage and restore cellular function, as are other damage-induced processes such as apoptosis, autophagy and senescence. The resilience of germ cells and embryos in response to DNA damage is less well studied compared with other cell types. Given that recent studies have described links between embryonic handling techniques and an increased likelihood of disease in post-natal life, an update is needed to summarize the sources of DNA damage in embryos and their capacity to repair it. In addition, numerous recent publications have detailed novel techniques for detecting and repairing DNA damage in embryos. This information is of interest to medical or scientific personnel who wish to obtain undamaged embryos for use in offspring generation by ART.

OBJECTIVE AND RATIONALE

This review aims to thoroughly discuss sources of DNA damage in male and female gametes and preimplantation embryos. Special consideration is given to current knowledge and limits in DNA damage detection and screening strategies. Finally, obstacles and future perspectives in clinical diagnosis and treatment (repair) of DNA damaged embryos are discussed.

SEARCH METHODS

Using PubMed and Google Scholar until May 2021, a comprehensive search for peer-reviewed original English-language articles was carried out using keywords relevant to the topic with no limits placed on time. Keywords included ‘DNA damage repair’, ‘gametes’, ‘sperm’, ‘oocyte’, ‘zygote’, ‘blastocyst’ and ‘embryo’. References from retrieved articles were also used to obtain additional articles. Literature on the sources and consequences of DNA damage on germ cells and embryos was also searched. Additional papers cited by primary references were included. Results from our own studies were included where relevant.

OUTCOMES

DNA damage in gametes and embryos can differ greatly based on the source and severity. This damage affects the development of the embryo and can lead to long-term health effects on offspring. DDR mechanisms can repair damage to a certain extent, but the factors that play a role in this process are numerous and altogether not well characterized. In this review, we describe the multifactorial origin of DNA damage in male and female gametes and in the embryo, and suggest screening strategies for the selection of healthy gametes and embryos. Furthermore, possible therapeutic solutions to decrease the frequency of DNA damaged gametes and embryos and eventually to repair DNA and increase mitochondrial quality in embryos before their implantation is discussed.

WIDER IMPLICATIONS

Understanding DNA damage in gametes and embryos is essential for the improvement of techniques that could enhance embryo implantation and pregnancy success. While our knowledge about DNA damage factors and regulatory mechanisms in cells has advanced greatly, the number of feasible practical techniques to avoid or repair damaged embryos remains scarce. Our intention is therefore to focus on strategies to obtain embryos with as little DNA damage as possible, which will impact reproductive biology research with particular significance for reproductive clinicians and embryologists.

Cryopreservation of human spermatozoa by freezing testicular seminiferous tubule with novel cryopiece

This study was carried out to evaluate the effectiveness of cryopreservation of human spermatozoa by freezing testicular seminiferous tubule with a new cryocarrier named ‘novel cryopiece’. Testicular tissue (TT) was collected from patients who underwent diagnostic testicular biopsy. Overall, 35 TT samples were obtained. Each TT sample was equally divided into four groups named (e.g. G1, G2, G3 and Gc). G1 was frozen as testicular seminiferous tubule using novel cryopiece, G2 was frozen as testicular cell suspensions using novel cryopiece, G3 was frozen as testicular cell suspensions using 0.25 ml straw, and Gc was not frozen. The samples in G1 and G2 experimental groups were cryopreserved in five separate aliquots and stored in the same cryovial. The freeze–thaw sperm DNA fragmentation index (DFI) of G2 was lower than that of G3 (20.27 ± 5.40 vs 23.55 ± 6.02; p = 0.004). After thawing, spermatozoa could be found in all 35 testicular seminiferous tubule specimens in G1; however, it could not be found in 2 of 35 (5.7%) and 1 of 35 (2.9%) testicular cell suspensions samples in G2 and G3 respectively. This study indicates that novel cryopiece presented for the cryopreservation of testicular seminiferous tubules and testicular cell suspension is simple and effective.

Sperm Selection Procedures for Optimizing the Outcome of ICSI in Patients with NOA

Retrieving spermatozoa from the testicles has been a great hope for patients with non-obstructive azoospermia (NOA), but relevant methods have not yet been developed to the level necessary to provide resolutions for all cases of NOA. Although performing testicular sperm extraction under microscopic magnification has increased sperm retrieval rates, in vitro selection and processing of quality sperm plays an essential role in the success of in vitro fertilization. Moreover, sperm cryopreservation is widely used in assisted reproductive technologies, whether for therapeutic purposes or for future fertility preservation. In recent years, there have been new developments using advanced technologies to freeze and preserve even very small numbers of sperm for which conventional techniques are inadequate. The present review provides an up-to-date summary of current strategies for maximizing sperm recovery from surgically obtained testicular samples and, as an extension, optimization of in vitro sperm processing techniques in the management of NOA.

Phosphatidylcholine and L-acetyl-carnitine-based freezing medium can replace egg yolk and preserves human sperm function

Background

Conventional cryopreservation methods induce chemical and mechanical damage to the sperm membranes. The cryoprotectant potential of phospholipids of vegetal origin as soybean lecithin has been investigated as a substitute for egg yolk in diluents used for the cryopreservation of human spermatozoa. Therefore, the objective of this study was comparing the efficacy of a synthetic cryoprotectant supplemented with L-α-phosphatidylcholine (PC) and L-acetyl-carnitine (ANTIOX-PC) and the standard egg-based TEST-yolk buffer (TYB) in preserving sperm motility and chromatin quality in cryopreserved semen samples.

Methods

Prospective experimental study in which semen samples from 63 men with normal sperm motility and 58 men with low sperm motility were included and analyzed both before and after cryopreservation using ANTIOX-PC or TYB freezing media. Sperm quality was evaluated by routine semen analysis and DNA fragmentation index using the Terminal deoxynucleotidyl transferase dUTP nick end labeling assay.

Results

Differences in the post-thaw progressive motility and DNA fragmentation index were not detected between TYB and ANTIOX-PC cryoprotectants in both normal and low sperm motility groups (P>0.05). However, ANTIOX-PC medium retained higher non-progressive motility and lower percentage of immotile sperm when compared to TYB medium, resulting in a greater total motile sperm count (P<0.05), regardless baseline values of motility characteristic of the normospermic or asthenozoospermic samples.

Conclusions

ANTIOX-PC medium was effective to protect human sperm during a freeze-thaw cycle compared to the TYB medium. A clinically relevant advantage in better preserving kinetic parameters as higher total motility and lower immotile post-thawed sperm from ANTIOX-PC, in normal and low motility semen samples, demonstrated the positive impact of phospholipid and antioxidant treatment on sperm cryotolerance with high potential for egg yolk lipids replacement and biosafety.

Self-reported physical health status of donor sperm-conceived adults

Donor-conceived neonates have poorer birth outcomes, including low birth weight and preterm delivery that are associated with poorer long-term health in adulthood through the developmental origins of health and disease (DOHaD) theory. The aim of this study was to conduct the first investigation of the adult health outcomes of donor-conceived people. An online health survey was completed by 272 donor sperm-conceived adults and 877 spontaneously conceived adults from around the world. Donor and spontaneously conceived groups were matched for age, sex, height, smoking, alcohol consumption, exercise, own fertility and maternal smoking. Donor sperm-conceived adults had significantly higher reports of being diagnosed with type 1 diabetes (P = 0.031), thyroid disease (P = 0.031), acute bronchitis (P = 0.008), environmental allergies (P = 0.046), sleep apnoea (P = 0.037) and having ear tubes/grommets surgically implanted (P = 0.046). This is the first study to investigate the health outcomes of adult donor sperm-conceived people. Donor sperm-conceived adults self-reported elevated frequencies of various health conditions. The outcomes are consistent with birth defect data from donor sperm treatment and are consistent with the DOHaD linking perturbed early growth and chronic disease in adulthood.

Co-incubation of spermatozoa with human follicular fluid reduces sperm DNA fragmentation by mitigating DNase activity in the seminal plasma

PURPOSE

To examine the effect of co-incubating spermatozoa with human follicular fluid (HFF) on the rate of sperm DNA fragmentation.

METHODS

This prospective study used semen (n = 23) and HFF from oocyte donors (n = 23). Liquified semen was divided into four aliquots: (1) neat semen (NEAT), (2) seminal plasma removed and replaced with sperm media (HTF) containing 0% (FF0), (3) 20% (FF20), or (4) 50% (FF50) HFF. Sperm motility and DNA fragmentation (SDF) were assessed following 24 h of incubation at 37 °C. Pro-oxidant capacity of HFF and seminal plasma and the effect of HFF on seminal plasma DNase activity was assessed in a sub-sample of 10 ejaculates.

RESULTS

Sperm motility was higher after 3 h of incubation in media that contained HFF compared to the NEAT sample or when sperm was diluted in media without HFF. r-SDF (increase of SDF per time unit) values after 24 h of incubation for NEAT, FF0, FF20 and FF50 were 0.91, 0.69, 0.25 and 0.36, respectively. While pro-oxidant capacity of seminal plasma samples showed large variation (mean: 94.6 colour units; SD 65.4), it was lower and more homogeneous in FF samples (mean: 29.9 colour units; SD: 6.3). Addition of HFF to seminal plasma appeared to inhibit DNase activity.

CONCLUSION

While differences exist in the pro-oxidant capacity of seminal plasma of patients, sperm DNA integrity was preserved with addition of HFF to sperm media, irrespective of the level of pro-oxidant capacity. DNase activity in the original seminal plasma was abolished after HFF co-incubation.

Failed sperm retrieval from severely oligospermic or non-obstructive azoospermic patients on oocyte retrieval day: Emergent oocyte cryopreservation is a feasible strategy

Purpose

Unexpected sperm retrieval failure on the day of oocyte retrieval is not common but frequently happened in patients with severe oligospermia or non-obstructive azoospermia(NOA). Oocyte cryopreservation is a common strategy after failed collection of sperm when concurrent ovarian stimulation is underwent. However, the use of oocyte vitrification in such male-infertility cases remains unclear.

Objective

To investigate the outcomes of emergent oocyte cryopreservation after failed sperm retrieval from severe oligospermic or non-obstructive azoospermic (NOA) patients on oocyte retrieval day.

Methods

Design: Retrospective cohort study

Setting: Academic fertility center at Lee Women's Hospital, Taiwan, between March 2015 and August 2017.

Patients: For 203 couples with NOA(n = 200) or severe oligospermia(n = 3), testicular spermatozoa (n = 67 cycles) or frozen donor sperm (n = 209 cycles) were injected into fresh or frozen-thawed oocytes via 276 intracytoplasmic sperm injection (ICSI) cycles.

Main Outcome Measures: Clinical pregnancy and live-birth rates (LBRs).

Results

In the 67 cycles involving the use of fresh testicular spermatozoa, no significant differences were observed between fresh and warmed oocytes with respect to the fertilization rates (69.2% vs. 74.1%; p = 0.27), number of Day-3 embryos (8.6±4.4 vs. 6.4±3.4; p = 0.08), number of good-quality Day-3 embryos (4.5±3.9vs. 4.7±3.0; p = 0.45), implantation rates (29.1% vs. 17.8%; p = 0.21), clinical pregnancy rates (36.4% vs. 26.8.0%; p = 0.81), live birth rates (36.4% vs. 14.3%; p = 0.46), or perinatal outcomes. In the 209 cycles involving the use of frozen donor sperm, no significant differences were seen between the two groups, except that the mean birth weights were significantly lower with fresh oocyte pregnancies than with warmed oocytes (2952±196 gm vs 2643±700 gm; p = 0.006).

Conclusions

Emergent oocyte cryopreservation is a feasible strategy to manage unexpected sperm retrieval failure from severe oligospermic or NOA patients on the oocyte retrieval day. There is no detrimental effect on the live birth rate when testicular spermatozoa or frozen donor sperm are injected into the thawed oocytes compared with fresh oocytes.

DNA integrity and methylation changes of mouse spermatozoa following prolonged incubation

Sperm quality can be affected by different factors including the length of incubation time between sperm preparation and intracytoplasmic sperm injection. Here, we have evaluated the level of DNA methylation and expressions of related genes in mice spermatozoa. The spermatozoa were divided into three groups: fresh, spermatozoa incubated at room temperature (RT) and 37°C for 24 hr. The sperm chromatin structure assay was used to determine the DNA fragmentation index (DFI), and DNA methylation was analysed by flow cytometry. The expression levels of DNA methylation-related genes were determined by quantitative real-time PCR (qRT-PCR). According to the results, we observed significantly higher sperm progressive motility and viability in the group incubated at RT compared to the spermatozoa incubated at 37°C (p < 0.05). Spermatozoa incubated at 37°C had a higher DFI compared to the other groups (p < 0.05), but the DNA methylation level significantly decreased (p < 0.05). qRT-PCR analysis showed increased Dnmt-1 expression in spermatozoa after 24-hr incubation at 37°C. However, there were significantly higher expression levels of Dnmt-3l, Dnmt-3a and Dnmt-3b after incubation at both RT and 37°C compared to the fresh group (p < 0.05). The 24-hr incubation period affected both sperm DNA methylation and integrity. This study indicated that incubation at RT resulted in better sperm quality.

An adapted carrier for the cryopreservation of human testicular spermatozoa

RESEARCH QUESTION

Does the adapted carrier Cryoplus improve the quality of cryopreserved spermatozoa compared with the use of conventional containers, and what is the effect of the adapted carrier on clinical outcomes?

DESIGN

Semen samples from 27 cases of oligozoospermia were used to investigate whether the adapted carrier improved cryopreserved sperm quality compared with the use of 0.25-ml straws and 2-ml cryogenic vials. Thirty testicular sperm samples were used to study the quality of testicular spermatozoa cryopreserved in the adapted carrier. The retrospective study included a further 104 men with azoospermia to investigate the clinical outcomes of testicular spermatozoa cryopreserved with the adapted carriers. Men with mostly obstructive azoospermia were included in this study.

RESULTS

The adapted carrier improved cryopreserved spermatozoa motility of semen samples compared with 2-ml cryogenic vials but not compared with 0.25-ml straws. No differences were found in cryopreserved sperm DNA fragmentation among the three carriers. Fertilization and good-quality embryo rates were similar in ICSI cycles using fresh or cryopreserved testicular spermatozoa. Additionally, no difference was evident between frozen-thawed embryo transfer cycles using fresh or cryopreserved testicular spermatozoa in clinical pregnancy, implantation, miscarriage, live birth rates or birth weight.

CONCLUSIONS

The adapted carrier improved the cryopreserved sperm motility compared with the effects of 2-ml cryogenic vials. The outcomes of intracytoplasmic sperm injection and frozen-thawed embryo transfer outcomes indicate that testicular spermatozoa cryopreserved using the adapted carrier is not inferior to fresh testicular spermatozoa. The use of the adapted carrier for cryopreserving human testicular spermatozoa especially from obstructive azoospermia is simple and effective.

Influence of extended incubation time on Human sperm chromatin condensation, sperm DNA strand breaks and their effect on fertilisation rate

The purpose of this study was to determine influence of extended incubation time on sperm chromatin condensation and DNA strand breaks and their effect on fertilisation rate. Forty couples undergoing ICSI therapy were included. Semen was prepared by PureSperm gradient centrifugation and divided into two parts. The first part (G1) was used immediately for ICSI, whereas the second part (G2) was kept in the incubator at 37°C, 5% and 90% Humidity for 5 hr, and thereafter, the capacitated spermatozoa were used for ICSI. The TUNEL test and chromomycin CMA3 were used to evaluate the DNA strand breaks and chromatin condensation respectively. The percentage of condensed chromatin was 73.92 ± 12.70 in the group 1 and 81.13 ± 10.31% in group 2 (p = .001). However, the double-strand breaks were 11.15 ± 8.67% in G.1 and 16.30 ± 11.12% in G.2. (p = .001). Fertilisation rate in the (Group 1) was 62.45% and 69.17% in (Group 2). There was a positive correlation between condensed chromatin and fertilisation rate (r = 0.846, p = .001) and a negative correlation with DNA double-strand breaks (r = -0.802; p = .001). In conclusion, the prolonged sperm incubation (5 hr) leads to a higher chromatin condensation and to a significantly increased number of DNA strands double breaks with no influence on fertilisation rates.

Long-term clinical outcomes of testicular sperm extraction and intracytoplasmic sperm injection for infertile men

Purpose

To find the best methods to achieve the highest pregnancy and birth rates for couples needing testicular sperm extraction (TESE)‐intracytoplasmic sperm injection (ICSI).

Methods

Retrospectively studied were 801 patients with male factor infertility who had undergone TESE‐ICSI between April, 1996 and July, 2016 and who had been categorized into four groups: obstructive azoospermia (OA); non‐obstructive azoospermia (NOA); Klinefelter syndrome (KS); and cryptozoospermia (Crypt). The sperm retrieval rate, hormone levels, fertilization rate (FR), pregnancy rate (PR), and birth rate (BR) after ICSI among three groups were compared: fresh testicular sperm (FS)‐fresh oocytes (FO) (Group I); frozen‐thawed testicular sperm‐FO (Group II); and FS‐vitrified‐warmed oocytes (Group III).

Results

The testicular sperm recovery rate was 57.8% (463/801): 89.6% in the Crypt, 97.1% in the OA, 28.9% in the NOA, and 42.2% in the KS groups. The follicle‐stimulating hormone levels were significantly higher in the NOA and KS groups and the testosterone levels were significantly lower in the KS group. The FR, PR, and BR were: 65.2%, 43.2%, and 28.5% in group I; 59.2%, 33.4%, and 18.7% in group II; and 56.4%, 33.8%, and 22.1% in group III.

Conclusion

Intracytoplasmic sperm injection with FS‐FO achieved the best PR and BR. It should be considered what to do in cases with no testicular sperm by TESE. The authors hope that ICSI with donor sperm will be allowed in Japan in the near future.

Longer time interval between semen processing and intrauterine insemination does not affect pregnancy outcome

OBJECTIVE

To study whether the pregnancy outcome of intrauterine insemination (IUI) is affected by a longer time interval between semen processing and insemination.

DESIGN

Retrospective cohort.

SETTING

Teaching hospital.

PATIENT(S)

Couples with subfertility and an indication for IUI over a 10-year period.

INTERVENTION (S)

Insemination performed the day after but within 24 hours of semen collection and processing (delayed insemination) compared with insemination performed immediately after sperm collection and processing (immediate insemination).

MAIN OUTCOME MEASURE(S)

Ongoing pregnancy rate, defined as a pregnancy confirmed by ultrasound at 10 to 12 weeks of gestation.

RESULT(S)

In total, 1,136 cycles were analyzed. In 77 of 547 couples (14%) an ongoing pregnancy occurred after delayed insemination, and in 77 of 589 couples (13%) an ongoing pregnancy occurred after immediate insemination. Both groups had similar baseline characteristics. After adjustment for confounders, there was no difference in the ongoing pregnancy rate between delayed as compared with immediate insemination (odds ratio 0.89; 95% confidence interval, 0.63-1.25).

CONCLUSION(S)

There is no negative effect on pregnancy rate when IUI of processed sperm is delayed until the next day. This approach allows additional flexibility for couples when the male partner is not available on the day of ovulation, and it allows for a spread of workload in the laboratory.

Role of Antioxidants in Assisted Reproductive Techniques

Oxidative stress (OS) has been recognized as a significant cause of suboptimal assisted reproductive outcome. Many of the sperm preparation and manipulation procedures that are necessary in the in vitro environment can result in excessive production of reactive oxygen species (ROS) thereby exposing the gametes and growing embryos to significant oxidative damage. Antioxidants have long been utilized in the management of male subfertility as they can counterbalance the elevated levels of ROS inducing a high state of OS. Few studies have looked into the clinical effectiveness of antioxidants in patients undergoing assisted reproduction. While an overall favorable outcome has been perceived, the specific clinical indication and optimal antioxidant regimen remain unknown. The goal of our review is to explore the sources of ROS in the in vitro environment and provide a clinical scenario-based approach to identify the circumstances where antioxidant supplementation is most beneficial to enhance the outcome of assisted reproduction.

Processing and selection of surgically-retrieved sperm for ICSI: a review

Although the technique of intracytoplasmic sperm injection (ICSI) has been a revolution in the alleviation of male infertility, the use of testicular sperm for ICSI was a formerly unseen breakthrough in the treatment of the azoospermic man with primary testicular failure. At the clinical level, different procedures of testicular sperm retrieval (conventional TESE, micro-TESE, FNA/TESA, MESA, PESA) are being performed, the choice is mainly based on the cause of azoospermia (obstructive versus non-obstructive) and the surgeon's skills. At the level of the IVF laboratory, mechanical procedures to harvest the sperm from the tissue may be combined with enzymatic treatment in order to increase the sperm recovery rates. A number of techniques have been developed for viable sperm selection in males with only immotile testicular sperm available. However, large, well-designed studies on the benefit and safety of one over the other technique are lacking. Despite all the available methods and combinations of laboratory procedures which have a common goal to maximize sperm recovery from testicular samples, a large proportion of NOA patients fail to father a genetically own child. Advanced technology application may improve recovery rates by detection of the testicular foci with active spermatogenesis and/or identification of the rare individual sperm in the testicular suspensions. On the other hand, in vitro spermatogenesis or sperm production from embryonic stem cells or induced pluripotent stem cells might be future options. The present review summarizes the available strategies which aim to maximize sperm recovery from surgically retrieved samples.

A meta-analysis of sperm donation offspring health outcomes

Although the use of donor sperm as a treatment modality for male infertility has become common place, the health outcomes for those conceived has been poorly studied. A structured search of the literature using PubMed, EMBASE and Cochrane Reviews was performed to investigate the health outcomes of offspring conceived from donor sperm. Eight studies were eligible and included in the review, and of these, three were included in a meta-analysis. Meta-analysis of clinical outcomes showed that donor sperm neonates are not at increased risk of being born of low birth weight (<2500 g), preterm (<37 weeks) or with increased incidences of birth defects, than spontaneously conceived neonates.

The effect of two cryopreservation methods on human sperm DNA damage

Several methods are currently available for selection when conducting sperm cryopreservation, however, these methods might cause different degrees of damage on sperm DNA. The aim of the this study is to compare the effects of storage at -80 °C (in ultra-low temperature refrigerator) and at -196 °C (in liquid nitrogen) on sperm DNA damage, thus to provide a reference for choosing the right method according to different aims. We randomly collected 28 semen samples from college students of Chongqing city. The samples stored at -80 °C were neat semen samples and the samples stored at -196 °C were mixed with additional cryoprotectants. Each sample was subjected to two freezing-thawing cycles, and the sperm DNA damage levels of fresh and thawed samples were measured by single cell gel electrophoresis (SCGE) and sperm chromatin structure assay (SCSA). Both SCGE and SCSA assays showed cryopreservation induced significant damage to sperm DNA. However, storage at -196 °C lead to more severe damage to sperm DNA than storage at -80 °C measured by SCSA. Sperm DNA damage increased simultaneously with the higher frequency of freezing-thawing cycles. We concluded that storage of neat semen samples at -80 °C had milder damage to sperm DNA than storage at -196 °C mixed with cryoprotectants. To avoid additional sperm DNA damage, repeated freezing and thawing should be prevented.

Validation-verification of a highly effective, practical human testicular tissue in vitro culture-cryopreservation procedure aimed to optimize pre-freeze and post-thaw motility

PURPOSE

The aim of our paper was to validate a testicular biopsy procedure that simplifies handling, processing, and cryopreservation, while at the same time optimizes sperm motility before freezing and after thawing.

METHODS

Two prospective studies were conducted to verify, optimize, and understand the virtues of pre-freeze testicular tissue IVC at different temperatures (21, 30, or 37 °C). Testicular tissue was obtained from clinical specimens designated for whole tissue cryopreservation (i.e., intact mass of tubules) and/or for fresh use in IVF-ICSI cycles. Whole testicular biopsy pieces (1-3 mm(3)) were diluted in glycerol containing freeze solutions, slow cooled to 4 °C and then rapidly frozen in LN2 vapor. Fresh and post-thaw testicular biopsy tissue were evaluated for changes in the quantity (%) and pattern of motility (I-IV: twitching to rapid progression, respectively) over a 1 week duration. The clinical effectiveness of IVC-cryopreserved whole testicular biopsy tissue was also validated analyzing fresh embryo transfers.

RESULTS

More reliable recovery of motile testicular sperm was achieved using whole tissue freeze preservation combined with IVC (24-96 h) post-acquisition at an incubation temperature of 30 °C compared to ambient temperature (21 °C) or 37 °C. Up to 85 % of the pre-freeze motility was conserved post-thaw (+3 h) for easy ICSI selection. Sperm longevity was optimized to fresh tissue levels by implementing testicular biopsy sucrose dilution post-thaw. Favorable clinical outcomes were proven using frozen-thawed testicular biopsy sperm for ICSI.

CONCLUSIONS

By employing minimal tissue manipulation, integrating pre-freeze IVC processing at 30 °C and the freezing of whole testicular biopsy tissue, we have reduced the labor and improved the efficacy of processing testicular tissue for freeze-preservation and subsequent ICSI use.

Comparison of reproductive outcome in oligozoospermic men with high sperm DNA fragmentation undergoing intracytoplasmic sperm injection with ejaculated and testicular sperm

OBJECTIVE

To investigate the effectiveness of intracytoplasmic sperm injection (ICSI) using testicular sperm as a strategy to overcome infertility in men with high sperm DNA fragmentation (SDF).

DESIGN

Prospective, observational, cohort study.

SETTING

Private IVF centers.

PATIENT(S)

A total of 147 couples undergoing IVF-ICSI and day 3 fresh ETs whose male partner has oligozoospermia and high SDF.

INTERVENTION(S)

Sperm injections were carried out with ejaculated sperm (EJA-ICSI) or testicular sperm (TESTI-ICSI) retrieved by either testicular sperm extraction (TESE) or testicular sperm aspiration (TESA). SDF levels were reassessed on the day of oocyte retrieval in both ejaculated and testicular specimens.

MAIN OUTCOME MEASURE(S)

Percentage of testicular and ejaculated spermatozoa containing fragmented DNA (%DFI) and clinical pregnancy, miscarriage, and live-birth rates.

RESULT(S)

The %DFI in testicular sperm was 8.3%, compared with 40.7% in ejaculated sperm. For the TESTI-ICSI group versus the EJA-ICSI group, respectively, the clinical pregnancy rate was 51.9% and 40.2%, the miscarriage rate was 10.0% and 34.3%, and the live-birth rate was 46.7% and 26.4%.

CONCLUSION(S)

ICSI outcomes were significantly better in the group of men who had testicular sperm used for ICSI compared with those with ejaculated sperm. SDF was significantly lower in testicular specimens compared with ejaculated counterparts. Our results suggest that TESTI-ICSI is an effective option to overcome infertility when applied to selected men with oligozoospermia and high ejaculated SDF levels.

Unpacking the mysteries of sperm DNA fragmentation

Although it has been thirty years since publication of one of the most influential papers on the value of assessing sperm DNA damage, andrologists have yet to reach a general consensus about how to apply this seminal parameter to improve or predict reproductive outcomes. Studies that have attempted to establish a causal relationship between sperm DNA damage and pregnancy success have often resulted in conflicting findings, eroding the practitioner’s confidence to incorporate this phenomenon into their appraisal of fertility. In this review we have identified and answered ten important unresolved questions commonly asked by andrologists with respect to the relationship between sperm DNA damage and fertility. We answer questions ranging from a basic comprehension of biological mechanisms and external factors that contribute to increased levels of sperm DNA damage in the ejaculate to what type of DNA lesions we might be expect to occur and what are some of the consequences of DNA damage on early embryonic development. We also address some of the fundamental technical issues associated with the most appropriate measurement of sperm DNA damage and the need to attenuate the confounding impacts of iatrogenic damage. We conclude by asking whether it is possible to reduce elevated levels of sperm DNA damage therapeutically.

Impact on ICSI outcomes of adding 24 h of in vitro culture before testicular sperm freezing: a retrospective study

Purpose

To compare sperm parameters and intracytoplasmic sperm injection (ICSI) outcomes for testicular spermatozoa frozen on the day of the biopsy (DO) with those frozen after 24 h of in vitro culture (D1).

Methods

In this retrospective study, from 1999 to 2012, forty-nine azoospermic patients were included to compare sperm (motility and viability) and outcomes (fertilization (FR), implantation (IR), pregnancy (PR) and delivery rates (DR)).

Results

The in vitro culture increased total motility (+2.8 %, p = 0.0161) but decreased viability (−8.3 %, p = 0.007). After 24 h of culture, the post-thaw changes in motility and viability were not significant. Twenty-six couples underwent ICSI: thirty–four ICSI were performed with spermatozoa cryopreserved at D0 and eighteen with spermatozoa frozen at D1. Cumulated IR and DR were lower for ICSI with D1 spermatozoa than with D0 spermatozoa (IR: 21.6 % with D0 vs. 9.8 % with D1, p = 0.102; DR: 27.5 % with D0 vs. 8.3 % with D1, p = 0.049).

Conclusion

Despite improving motility, freezing spermatozoa 24 h after testicular biopsy had a potential negative effect on ICSI outcomes, notably on delivery rates. These results may be related to the detrimental impact of the additional culture on the nuclear integrity of sperm.

Impact of fresh versus cryopreserved testicular sperm upon intracytoplasmic sperm injection pregnancy outcomes in men with azoospermia due to spermatogenic dysfunction: a meta-analysis

OBJECTIVE

To determine if clinical pregnancy rates and fertilization rates with the use of cryopreserved sperm for intracytoplasmic sperm injection (ICSI) in patients with azoospermia due to spermatogenic dysfunction (i.e., nonobstructive azoospermia) are similar to those with fresh sperm.

DESIGN

Systematic review and meta-analysis.

SETTING

Academic medical center.

PATIENT(S)

Azoospermic men secondary to spermatogenic dysfunction.

INTERVENTION(S)

Not applicable.

MAIN OUTCOME MEASURE(S)

Clinical pregnancy rate, fertilization rate.

RESULT(S)

Eleven studies met criteria for the outcome of clinical pregnancy rate. Seventy-nine (28.7%) of 275 intracytoplasmic sperm injection cycles using fresh testicular sperm resulted in a clinical pregnancy, compared with 84 (28.1%) of 299 intracytoplasmic sperm injection cycles using cryopreserved sperm (relative risk [RR] 1.00, 95% confidence interval [CI] 0.75-1.33). Ten studies met criteria for the outcome of fertilization rate. A total of 1,422 (52.9%) of 2,687 oocytes injected with fresh testicular sperm were fertilized, compared with 1,490 (54.0%) of 2,757 oocytes injected with cryopreserved sperm (RR 0.97, 95% CI 0.92-1.02).

CONCLUSION(S)

In men with azoospermia due to spermatogenic dysfunction, there is no statistical difference between the use of fresh versus cryopreserved-thawed testicular sperm when assessing clinical pregnancy or fertilization rates in couples undergoing ICSI.

Sperm selection: effect on sperm DNA quality

The selection of spermatozoa without DNA fragmentation and chromosomal diseases prior to assisted reproductive techniques helps to optimize the outcome of the treatment; in particular, sperm selection prior to in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI) is crucial. In fact, although ICSI has been successfully and safely applied worldwide for almost 20 years, at the present time we have no real knowledge regarding the hypothetical long-term side effects on ICSI adults, given the increased likelihood of spermatozoa with defective nuclear content fertilizing oocytes.In the case of DNA damage, the basal sperm DNA fragmentation rate can be significantly reduced by some sperm processing procedures that improve the percentage of spermatozoa with normal chromatin structure by filtering out DNA-damaged spermatozoa. After this first step, new advances in micromanipulation can be performed to choose the "ideal" mature spermatozoa for ICSI, reducing potential damage to the gametes. In fact, it is possible to prevent fertilization by DNA-damaged and chromosomal-unbalanced spermatozoa by selecting ICSI sperm by maturation markers such as hyaluronic acid or other zona pellucida receptors. Furthermore, novel noninvasive imaging techniques can be valid tools for helping in the morphological selection of ICSI spermatozoa.

An improved experimental model for understanding the impact of sperm DNA fragmentation on human pregnancy following ICSI

Using donor oocytes of proven fertility, the effect of sperm DNA fragmentation (SDF) and motility on reproductive success was examined in 70 couples undergoing ICSI. Both SDF and sperm motility were assessed at the time of sperm injection and using the same sperm sample that was processed for ICSI. While there was no difference in the fertilization rate, cleavage rate, embryo quality, or sperm motility between pregnant and nonpregnant couples, the SDF of nonpregnant couples (SDF = 23.9%) was higher than that of pregnant couples (SDF = 17.0%; U Mann-Whitney 347; P = .002). Using a combination of the sensitivity and specificity measures from the production of ROC (receiver-operating characteristic) curves and the Youden index, we determined a threshold SDF value for our data set of 17% for predicting pregnancy (77.8% sensitivity and 71.1% specificity). Our results suggest that proven donor oocytes in combination with SDF assessment at the time of sperm injection represent a useful experimental model for reducing the confounding influences of sperm DNA repair by the oocyte and iatrogenic sperm damage.

Sperm processing by swim-up and density gradient is effective in elimination of sperm with DNA damage

PURPOSE

DNA damage may occur during sperm processing, thereby negatively influencing fertilizing ability of the sperm. The present study was designed to compare the effectiveness of gradient and swim-up, either alone or in combination, to eliminate sperm with DNA damage.

METHODS

A total of 51 subjects visiting the University infertility clinic with normozoospermic parameters, oligozoospermia and teratozoospermia were included. Semen characteristics were analysed by standard criteria; Terminal deoxy nucelotidyl transferase mediated dUTP nick end labeling assay was employed for DNA damage assessment.

RESULTS

The percentage of TUNEL positive sperm after sperm processing was significantly lower in normozoospermic (P < 0.05), oligozoospermic (P < 0.001) and teratozoospermic samples (P < 0.01). No difference was observed in the incidence of TUNEL positive sperm between the various techniques, suggesting that they are comparable.

CONCLUSIONS

Sperm preparation has been found to result in enrichment of sperm with intact chromatin, which is likely to improve the chances of achieving a viable pregnancy.

Male factor infertility and ART

For years, the management and treatment of male factor infertility has been 'experience' and not 'evidence' based. Although not evidence-based, current clinical practice involves extensive use of assisted reproductive techniques (ART). Where specific treatments are not indicated or have failed, ART have become popular adjunctive treatments for alleviating male factor infertility. According to the limited evidence available, intrauterine insemination (IUI) may be considered as a first-line treatment in a couple in which the female partner has a normal fertility status and at least 1×10(6) progressively motile spermatozoa are recovered after sperm preparation. If no pregnancy is achieved after 3-6 cycles of IUI, optimized in vitro fertilization (IVF) can be proposed. When less than 0.5×10(6) progressively motile spermatozoa are obtained after seminal fluid processing or sperm are recovered surgically from the testis or epididymis, intracytoplasmic sperm injection (ICSI) should be performed. Although the outcome of no other ART has ever been scrutinized as much before, no large-scale 'macroproblems' have as yet been observed after ICSI. Yet, ICSI candidates should be rigorously screened before embarking on IVF or ICSI, and thoroughly informed of the limitations of our knowledge on the hereditary aspects of male infertility and the safety aspects of ART.

Dynamics of sperm DNA damage in fresh versus frozen-thawed and gradient processed ejaculates in human donors

The rate of increase of sperm DNA fragmentation (rsDF) in fresh and frozen-thawed and processed sperm samples after a density gradient for sperm selection was analysed after 0, 0.5, 1.5, 4.5, 6, 24, 48 and 72 h of incubation at 37 °C, in five donors with proven fertility. The results showed that: (i) sperm DNA fragmentation (sDF) at baseline in fresh samples (14.3 ± 3.3) was lower than that obtained after freeze-thawing and selection (19.4 ± 4.1), significant differences; (ii) After 6 h of incubation the mean sDF in fresh samples (24.2 ± 10.2) was significantly lower than that in frozen-thawed samples (45.3 ± 7.1); (iii) Subsequently, the rsDF in fresh semen samples was 1.6% per h after 6 h of incubation, while after thawing and selection the rsDF was 4.3% per h; The tendency to increase in sDF showed high R(2) values (R(2) = 0.90) for exponential functions in case of fresh samples, whereas R(2) values for linear functions were higher after sperm selection (R(2) = 0.97). These results indicate that differences in sperm DNA fragmentation dynamics before and after storage are an important issue that must be considered for storage of sperm to be used for artificial reproduction techniques.

Sperm nuclear DNA fragmentation and chromatin structure in one-day-old ejaculated sperm

Objective

To evaluate sperm nuclear DNA fragmentation and chromatin structure after 18 hours'incubation at room temperature.

Methods

Twenty-eight male partners who participating IVF treatment were prospectively included in this study. Ejaculated sperm count and motility were assessed. The sperm was then immediately processed by the conventional swim-up method. After utilization of some of the sample for routine clinical use, the remainder of each of the samples was divided into two aliquots. One aliquot was immediately assessed for sperm nuclear DNA fragmentation (TUNEL assay) and chromatin structure (toluidine blue [TB] staining). The other aliquot was incubated at room temperature for 18 hours and then assessed by two methods. Only dark-TB sperms were considered as having abnormal chromatin structure. Data before and after extended incubation were compared using a paired Student's t-test.

Results

Before and after extended culture, nuclear DNA fragmentation assessed by TUNEL was 4.9±4.7% and 7.0±6.4%, respectively (p=0.008). The proportion of abnormal chromatin structure (dark-TB sperm) was 8.2±5.6% and 10.3±6.5% (p<0.001), before and after incubation, respectively.

Conclusion

After 18 hours' incubation at room temperature, sperm nuclear DNA and chromatin structure were significantly affected. The IVF practitioner should bear this information in mind when performing delayed insemination, especially for in vitro maturation cycles.

Preparation and incubation conditions affect the DNA integrity of ejaculated human spermatozoa

Appropriate semen processing and assessment are critical for successful infertility treatment. We investigated whether laboratory procedures including semen preparation and incubation affect sperm DNA integrity. A total of 153 infertile men were involved. Conventional semen parameters and sperm chromatin structure assay (SCSA) parameters, that is, DNA fragmentation index (%DFI) and high DNA stainability (%HDS), were assessed on the fresh ejaculated semen samples, which were treated and incubated under different conditions. Negative correlations were identified between the %DFI and sperm concentration, motility, progressive motility and morphology. A lower percentage of DFI was detected in spermatozoa when density gradient centrifugation (DGC) was followed by swim-up treatment in comparison with DGC alone (P < 0.01). Although the %DFI increased in a time-dependent manner with incubation both at room temperature (RT) and at 37 degrees C in air, the %DFI after 24 h at RT was significantly lower than that at 37 degrees C (P < 0.05). Incubation with 5% CO2 was effective in maintaining sperm motility (P < 0.01); however, it induced further elevation of %DFI (P < 0.001). Thus, sperm DNA damage was associated with longer incubation periods. Interestingly, common culture conditions, such as maintaining pH and temperature, compromised the sperm DNA integrity.

Sperm DNA fragmentation: mechanisms of origin, impact on reproductive outcome, and analysis

OBJECTIVE

To review the mechanisms responsible for DNA fragmentation in human sperm, including those occurring during spermatogenesis and transport through the reproductive tract. The mechanisms examined include: apoptosis in the seminiferous tubule epithelium, defects in chromatin remodeling during the process of spermiogenesis, oxygen radical-induced DNA damage during sperm migration from the seminiferous tubules to the epididymis, the activation of sperm caspases and endonucleases, damage induced by chemotherapy and radiotherapy, and the effect of environmental toxicants. The different tests currently used for sperm DNA fragmentation analysis and the factors that determine the predictive value of sperm DNA fragmentation testing and their implications in the diagnosis and treatment of infertility are also discussed. Finally, we also scrutinize how the presence in the embryonic genome of DNA strand breaks or modifications of DNA nucleotides inherited from the paternal genome could impact the embryo and offspring. In particular we discuss how abnormal sperm could be dealt with by the oocyte and how sperm DNA abnormalities, which have not been satisfactorily repaired by the oocyte after fertilization, may interfere with normal embryo and fetal development.

CONCLUSION(S)

Sperm DNA can be modified through various mechanisms. The integrity of the paternal genome is therefore of paramount importance in the initiation and maintenance of a viable pregnancy both in a natural conception and in assisted reproduction. The need to diagnose sperm at a nuclear level is an area that needs further understanding so that we can improve treatment of the infertile couple.

Rapid rates of sperm DNA damage after activation in tench (Tinca tinca: Teleostei, Cyprinidae) measured using a sperm chromatin dispersion test

Spermatozoal haplotypic DNA is prone to damage, leading to male fertility problems. So far, the assessment of sperm DNA breakage has been challenging because protamines render the nuclear chromatin highly compacted. Here, we report the application of a new test to quantify DNA fragmentation in spermatozoa of an externally fertilizing teleost fish. The sperm chromatin dispersion (SCD) test uses a species-specific lysing solution to generate controlled protein depletion that, followed by DNA-specific fluorescent labelling, allows an easy morphological discrimination between nuclei affected by DNA damage. Using tench (Tinca tinca) as our model, we first trialled the test against established, but more technically demanding, assays employing in situ nick translation (ISNT) and the comet assay. The SCD test showed high concordance with ISNT, comet assay measures and a chromatin-swelling test, confirming the application of this straightforward SCD technique to various aspects of reproductive biology. Second, we examined between-male variation in DNA damage, and measured changes through time following spermatozoal activation. Between-male variation in the basal levels of average DNA damage ranged from 0 to 20% of sperm showing damage, and all showed increases in DNA fragmentation through time (0-60 min). The rates of DNA damage increase are the fastest so far recorded in sperm for a living organism, and may relate to the external fertilization mode. Our findings have relevance for broodstock selection and optimizing IVF protocols routinely used in modern aquaculture.

Pregnancies and live births following ICSI with testicular spermatozoa after repeated implantation failure using ejaculated spermatozoa

The use of testicular spermatozoa for IVF/intracytoplasmic sperm injection (ICSI) is currently indicated exclusively for patients with azoospermia, since a favourable outcome is expected even when very few spermatozoa are present in the ejaculate. Here, a series of four couples with long-standing male factor infertility and multiple failed IVF/ICSI cycles are described. In all couples, the use of ejaculated spermatozoa for ICSI resulted in poor embryo quality and repeated implantation failure. Testicular sperm aspiration was performed in subsequent cycles, and testicular spermatozoa were used for ICSI. Embryo implantation and ongoing pregnancies/deliveries were achieved in all four couples. It is postulated that spermatozoa are subjected to post-testicular damage during sperm transport between the seminiferous tubules and epididymis, with the injection of damaged spermatozoa being the cause for repetitive IVF/ICSI failures. In selected patients, the use of testicular spermatozoa for IVF/ICSI should be considered, even when motile spermatozoa can be identified in the ejaculate.

Effect of thawing temperature on the motility recovery of cryopreserved human spermatozoa

OBJECTIVE

To investigate the effects of thawing temperature on sperm function after cryopreservation. The technical aspects of sperm cryopreservation have significantly improved over the last few decades. However, a standard protocol designed to optimize sperm motility recovery after thawing has not yet been established.

DESIGN

Prospective study.

SETTING

Private infertility institute and university-based research laboratory.

PATIENT(S)

Eighty consenting normozoospermic patients consulting for infertility.

INTERVENTION(S)

Spermatozoa from donor semen samples were thawed at different temperatures.

MAIN OUTCOME MEASURE(S)

Sperm motility, viability, adenosine-5'-triphosphate (ATP) content, acrosomal status, and DNA integrity were evaluated as a function of thawing temperature in cryopreserved human sperm samples.

RESULT(S)

Thawing at 40 degrees C resulted in a statistically significant increase in sperm motility recovery compared with thawing at temperatures between 20 degrees C and 37 degrees C. There were no statistically significant differences in sperm viability, acrosomal status, ATP content, and DNA integrity after thawing at 40 degrees C compared with thawing at temperatures between 20 degrees C and 37 degrees C.

CONCLUSION(S)

Sperm thawing at 40 degrees C could be safely used to improve motility recovery after sperm cryopreservation.