Delayed fertilization and poor embryonic development associated with impaired semen quality

Addition of Cryoprotectant DMSO Reduces Damage to Spermatozoa of Yellow Catfish (Pelteobagrus fulvidraco) during Cryopreservation: Ultrastructural Damage, Oxidative Damage and DNA Damage

Spermatozoa cryopreservation protocols have been established for yellow catfish (Pelteobagrus fulvidraco), but cryopreservation can still cause cellular damage and affect spermatozoa viability and fertility. Therefore, the aim of this paper was to evaluate the effects of adding or not adding cryoprotectants during low-temperature storage on the ultrastructural damage, oxidative damage, and DNA damage of thawed yellow catfish spermatozoa. The mixed semen of three male yellow catfish was divided into a fresh spermatozoa group, a frozen spermatozoa group (DMSO+) with a cryoprotectant (10% DMSO), and a frozen spermatozoa group without a cryoprotectant (DMSO-). Ultrastructural of the spermatozoa after thawing were observed under an electron microscope and the spermatozoa were assayed for SOD, MDA, and T-AOC enzyme activities, as well as for DNA integrity. In terms of movement parameters, compared with DMSO-, the addition of DMSO has significantly improved sperm motility, curve line velocity (VCL), and straight line velocity (VSL). The ultrastructural results showed that although thawed spermatozoa exhibited increased damage than fresh spermatozoa, 10% DMSO effectively reduced the damage to the plasma membrane, mitochondria, and flagellum of spermatozoa by cryopreservation, and most of the spermatozoa were preserved with intact structure. The results of oxidative damage showed that compared with frozen spermatozoa, 10% DMSO significantly increased the activities of SOD and T-AOC enzymes and clearly reduced the activity of the MDA enzyme. The antioxidant capacity of spermatozoa was improved, lipid peroxidation was reduced, and the oxidative damage caused by cryopreservation was mitigated. The DNA integrity of spermatozoa showed that 10% DMSO clearly reduced the DNA fragmentation rate. In conclusion, 10% DMSO can effectively reduce the ultrastructural damage, oxidative damage, and DNA damage of yellow catfish spermatozoa during cryopreservation; it can also further optimize the cryopreservation protocol for yellow catfish spermatozoa. Meanwhile, it also provides a theoretical basis for the future optimization of the cryopreservation protocols.

Automated Single-Sperm Selection Software (SiD) during ICSI: A Prospective Sibling Oocyte Evaluation

The computer-assisted program SiD was developed to assess and select sperm in real time based on motility characteristics. To date, there are limited studies examining the correlation between AI-assisted sperm selection and ICSI outcomes. To address this limit, a total of 646 sibling MII oocytes were randomly divided into two groups as follows: the ICSI group (n = 320): ICSI performed with sperm selected by the embryologist and the ICSI-SiD group (n = 326): ICSI performed with sperm selected using SiD software. Our results show a non-significant trend towards improved outcomes in the ICSI-SiD group across various biological parameters, including fertilization, cleavage, day 3 embryo development, blastocyst development, and quality on day 5. Similarly, we observed a non-significant increase in these outcomes when comparing both groups with sperm selection performed by a junior embryologist. Embryo development was monitored using a timelapse system. Some fertilization events happen significantly earlier when SiD is used for ICSI, but no significant difference was observed in the ICSI-SiD group for other timepoints. We observed comparable cumulative early and clinical pregnancy rates after ICSI-SiD. This preliminary investigation illustrated that employing the automated sperm selection software SiD leads to comparable biological outcomes, suggesting its efficacy in sperm selection.

Haploid Parthenogenetic Embryos Exhibit Unique Stress Response to pH, Osmotic and Oxidative Stress

Preimplantation-stage embryos are susceptible to various types of stress when cultured in vitro. Parthenogenetic embryos that lack spermatozoa contribution exhibit aberrant developmental dynamics due to their uniparental origin. Herein, we assessed whether the absence of paternal genome affects the susceptibility of the embryos to pH, osmotic and oxidative stress. Haploid parthenogenetic embryos (HPE) (activated oocytes with 1 pronucleus and 2 polar bodies) were generated by incubating cumulus oocyte complexes of Swiss albino mice with 10 mM strontium chloride for 3 h. Normally fertilized embryos (NFE) (fertilized oocytes with 2 pronuclei and 2 polar bodies) were derived using in vitro fertilization. At 2-cell stage, both HPE and NFE were exposed to various stressors including pH (6.8 to 8.2), osmotic (isotonic, hypotonic, and hypertonic), and peroxidatic oxidative (H2O2, 25 µM) stress. Endoplasmic reticulum stress response, mitochondrial membrane potential, and the rate of blastocyst development were assessed. HPE were susceptible to alteration in the pH that was well tolerated by NFE. Similarly, HPE displayed remarkable difference in sensitivity to hypertonic stress and oxidative stress compared to NFE. The results clearly indicate that the oocytes that develop into embryos in the absence of paternal contribution are more vulnerable to environmental stressors, further highlighting the importance of spermatozoa contribution and/or the ploidy status in mitigating these stressors and towards healthy early embryo development.

Intracytoplasmic sperm injection cycle success in patients under 35 years old with diminished ovarian reserve plus severe male factor

OBJECTIVE

We aimed to evaluate intracytoplasmic sperm injection (ICSI) outcomes in young patients with diminished ovarian reserve (DOR) plus severe male factor (SMF) compared with age-matched controls with DOR.

STUDY DESIGN

A total of 189 infertile women under 35 years with DOR undergoing ICSI procedures were included retrospectively. Participants whose partners' sperm analysis was normal considered as the DOR group (n = 154) and whose partners' had SMF considered as the DOR + SMF group (n = 35). The two groups were compared regarding cycle characteristics and pregnancy outcomes.

RESULTS

Demographic features except infertility duration were similar between two groups. The duration of infertility was significantly longer in the DOR + SMF group compared to the DOR group (p = 0.02). Ovarian stimulation characteristics, oocyte retrieval parameters, fertilization rate, quality of embryos, embryo cancellation rate, and development up to blastocyst stage were found similar between two groups. Implantation, clinical pregnancy, abortion, and live birth rate, multiple pregnancy rate per cycle were distributed homogenously between the DOR and DOR + SMF groups. Regarding perinatal and neonatal outcomes of groups, fetal height and weight were significantly lower in DOR + SMF group than in DOR group (p = 0.001 and 0.01, respectively). Gestational week at delivery was lower in the DOR + SMF group compared to the DOR group (p < 0.0001).

CONCLUSION

Fetal anthropometric measures were lower regarding to preterm delivery in the DOR + SMF group than the DOR group. Large sample-sized studies should be performed to explain the decreased gestational week at the time of delivery in the DOR + SMF group.

The outcome of intra-cytoplasmic sperm injection (ICSI): do the sperm concentration and motility matter?

OBJECTIVES

The male-factor subfertility was reported to be 30% globally; thus, the intracytoplasmic sperm injection (ICSI) procedure was implemented to improve the overall in vitro fertilization (IVF) rates. Nevertheless, at least 10% of fertilization failure still occurs. Concerning this issue, we explored the association of sperm concentration and motility with the quality of embryo development and pregnancy outcome in IVF-ICSI cycles.

METHODS

Retrospective analysis of 109 couples with male factor were done over 14 months in a tertiary university hospital in Malaysia. The data were divided into four groups; Group I: normal sperm parameters, Group II: normal sperm concentration but reduced total sperm motility, Group III: reduced sperm concentration and motility, Group IV: reduced sperm concentration but normal sperm motility. Only fresh semen samples and fresh embryo transfers were included. The fertilization, cleavage rate, embryo quality and pregnancy outcome were assessed.

RESULTS

Overall, group I had the highest oocytes yield and ICSI attempted; (10.12 + 6.50), whereas the lowest was in group IV; (7.00 + 2.82). Group II revealed the highest fertilization and cleavage rates; (54.14 + 25.36), (55.16 + 26.06), thus not surprisingly resulting in the highest number of good embryos and highest clinical pregnancy rates. The lowest cleavage and pregnancy rates were seen in group IV. However, all the outcomes were not statically significant (p>0.05).

CONCLUSIONS

Similar fertilization rate and comparable pregnancy outcome was seen among couples with normal and reduced sperm concentration and motility.

Reproductive Chances of Men with Azoospermia Due to Spermatogenic Dysfunction

Non-obstructive azoospermia (NOA), or lack of sperm in the ejaculate due to spermatogenic dysfunction, is the most severe form of infertility. Men with this form of infertility should be evaluated prior to treatment, as there are various underlying etiologies for NOA. While a significant proportion of NOA men have idiopathic spermatogenic dysfunction, known etiologies including genetic disorders, hormonal anomalies, structural abnormalities, chemotherapy or radiation treatment, infection and inflammation may substantively affect the prognosis for successful treatment. Despite the underlying etiology for NOA, most of these infertile men are candidates for surgical sperm retrieval and subsequent use in intracytoplasmic sperm injection (ICSI). In this review, we describe common etiologies of NOA and clinical outcomes following surgical sperm retrieval and ICSI.

The impact of fresh and frozen testicular tissue quality on embryological and clinical outcomes

Our ability to predict the potential of testicular spermatozoa to support embryonic development is still limited. Although motility of testicular spermatozoa is associated with embryo development, the impact of morphology and the presence of spermatozoa in the testicular sample has not been previously researched. Moreover, while the majority of data indicate no effect of cryopreservation, there are studies reporting impaired clinical outcomes due to testicular cryopreservation. In a retrospective study, 118 ICSI-TESE cycles were analysed to study the impact of (a) total quality of testicular tissue, (b) testicular tissue cryopreservation and (c) presence/motility/morphology of testicular spermatozoa in fertilisation rate, embryonic development, clinical pregnancy (CPR), ongoing pregnancy (OPR) and live birth rate (LBR). Results showed that fertilisation rate was significantly affected by both total quality of testicular tissue (p < .05) and rare presence of spermatozoa (p < .01). Moreover, total tissue quality (p < .01), cryopreservation of low-quality samples (p < .01), absence of motile testicular spermatozoa (p < .01) and poor spermatozoa morphology (p < .05) had a negative impact on the number of good quality day 3 embryos. CPR, OPR or LBR was not affected by any parameters examined. Our data suggest that the quality of testicular tissue influences both fertilisation rate and embryo development. Moreover, cryopreservation of low-quality testicular samples has a negative impact on the number of available embryos for transfer.

Impact of Cryopreservation on Spermatozoa Freeze-Thawed Traits and Relevance OMICS to Assess Sperm Cryo-Tolerance in Farm Animals

Sperm cryopreservation is a powerful tool for the livestock breeding program. Several technical attempts have been made to enhance the efficiency of spermatozoa cryopreservation in different farm animal species. However, it is well-recognized that mammalian spermatozoa are susceptible to cryo-injury caused by cryopreservation processes. Moreover, the factors leading to cryo-injuries are complicated, and the cryo-damage mechanism has not been methodically explained until now, which directly influences the quality of frozen–thawed spermatozoa. Currently, the various OMICS technologies in sperm cryo-biology have been conducted, particularly proteomics and transcriptomics studies. It has contributed while exploring the molecular alterations caused by cryopreservation, identification of various freezability markers and specific proteins that could be added to semen diluents before cryopreservation to improve sperm cryo-survival. Therefore, understanding the cryo-injury mechanism of spermatozoa is essential for the optimization of current cryopreservation processes. Recently, the application of newly-emerged proteomics and transcriptomics technologies to study the effects of cryopreservation on sperm is becoming a hotspot. This review detailed an updated overview of OMICS elements involved in sperm cryo-tolerance and freeze-thawed quality. While also detailed a mechanism of sperm cryo-injury and utilizing OMICS technology that assesses the sperm freezability potential biomarkers as well as the accurate classification between the excellent and poor freezer breeding candidate.

Hollow fiber vitrification allows cryopreservation of embryos with compromised cryotolerance

PURPOSE

This study aims to demonstrate vitrification methods that provide reliable cryopreservation for embryos with compromised cryotolerance.

METHODS

Two-cell stage mouse embryos and in vitro produced porcine embryos were vitrified using the hollow fiber vitrification (HFV) and Cryotop (CT) methods. The performance of these two methods was compared by the viability of the vitrified-rewarmed embryos.

RESULTS

Regardless of the method used, 100% of the mouse 2-cell embryos developed successfully after vitrification-rewarming into the blastocyst stage, whereas vitrification tests using porcine morulae with the HFV method produced significantly better results. The developmental rates of vitrified porcine morula into the blastocyst stage, as well as blastocyst cell number, were 90.3% and 112.3 ± 6.9 in the HFV group compared with 63.4% and 89.5 ± 8.1 in the CT group (P < .05). Vitrification tests using 4- to 8-cell porcine embryos resulted in development into the blastocyst stage (45.5%) in the HFV group alone, demonstrating its better efficacy. The HFV method did not impair embryo viability, even after spontaneous rewarming at room temperature for vitrified embryos, which is generally considered a contraindication.

CONCLUSION

Vitrification test using embryos with compromised cryotolerance allows for more precise determining of effective cryopreservation methods and devices.

Colloid centrifugation of fresh semen improves post-thaw quality of cryopreserved dromedary camel spermatozoa

Colloids have been successfully used in a number of species to improve sperm populations for IVF and for cryopreservation The usefulness of Single Layer Centrifugation (SLC) for freezing dromedary camel spermatozoa in two different extenders was evaluated by examining the motility, viability, acrosome status, DNA integrity, and ability of cryopreserved sperm to penetrate oocytes in vitro in a heterologus IVF system. Two ejaculates from each of five males were divided into four aliquots: two were processed by SLC (selected) while two were centrifuged without colloid (control). Pellets were cryopreserved in Green Buffer or INRA-96® containing 3% glycerol and evaluated at 0 and 1 h post thawed. The SLC improved post-thaw total and progressive motility at 0 (both P < 0.0001) and 1 (P < 0.001; P < 0.01, respectively) h, and STR (both P < 0.05) and BCF (both P < 0.001) at 0 h. Sperm viability and acrosome integrity (both P < 0.001) were improved at both time points. Sperm frozen in Green Buffer had greater total and progressive motilities at 0 (both P < 0.001) and 1 (both P < 0.001) h than INRA-96® samples. Spermatozoa in Green Buffer also had a greater VAP, VCL and VSL at 0 h and improved viability and acrosome integrity at 0 h (P < 0.05; P = 0.001, respectively) and 1 h (P < 0.05; P < 0.001, respectively). Viability of SLC spermatozoa was improved in Green Buffer at 1 h (P < 0.05). Oocyte penetration (P < 0.05) and pronuclear formation (P < 0.01) were greater with SLC-selected spermatozoa than non-selected spermatozoa, regardless of extender. No difference was observed between treatments or extenders in the mean number of spermatozoa per oocyte penetrated. The SLC spermatozoa had less (P < 0.01) DNA fragmentation compared to controls. The DNA fragmentation was moderately and negatively correlated with penetration (r = -0.4162; P = 0.02) and pronuclear formation (r = -0.3390; P < 0.01). In conclusion, colloid centrifugation of spermatozoa and cryopreservation in Green Buffer improves post thaw motility variables and IVF performance of dromedary camel spermatozoa.

Paternal influence of sperm DNA integrity on early embryonic development

STUDY QUESTION

Does sperm DNA damage affect early embryonic development?

SUMMARY ANSWER

Increased sperm DNA damage adversely affects embryo quality starting at Day 2 of early embryonic development and continuing after embryo transfer, resulting in reduced implantation rates and pregnancy outcomes.

WHAT IS KNOWN ALREADY

Abnormalities in the sperm DNA in the form of single and double strand breaks can be assessed by an alkaline Comet assay. Some prior studies have shown a strong paternal effect of sperm DNA damage on IVF outcome, including reduced fertilization, reduced embryo quality and cleavage rates, reduced numbers of embryos developing into blastocysts, increased percentage of embryos undergoing developmental arrest, and reduced implantation and pregnancy rates.

STUDY DESIGN, SIZE, DURATION

A cross-sectional study of 215 men from infertile couples undergoing assisted reproduction techniques at the University of Utah Center for Reproductive Medicine.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Sperm from men undergoing ART were analyzed for DNA damage using an alkaline Comet assay and classified into three groups: 'low damage' (0-30%), 'intermediate damage' (31-70%) and 'high damage' (71-100%). The cause of couples' infertility was categorized into one of the three types (male, female or unexplained). Each embryo was categorized as 'good', 'fair' or 'poor' quality, based on the number and grade of blastomeres. The influence of sperm DNA damage on early embryonic development was observed and classified into four stages: peri-fertilization effect (fertilization rate), early paternal effect (embryonic days 1-2), late paternal effect (embryonic days 3-5) and implantation stage effect.

MAIN RESULTS AND THE ROLE OF CHANCE

The paternal effect of sperm DNA damage was observed at each stage of early embryonic development. The peri-fertilization effect was higher in oocytes from patients with female infertility (20.85%) compared with male (8.22%; P < 0.001) and unexplained (7.30%; P < 0.001) infertility factors. In both the early and late paternal effect stages, the low DNA damage group had a higher percentage of good quality embryos (P < 0.05) and lower percentage of poor quality embryos (P < 0.05) compared with the high DNA damage group. Implantation was lower in the high DNA damage (33.33%) compared with intermediate DNA damage (55.26%; P < 0.001) and low DNA damage (65.00%; P < 0.001) groups. The implantation rate was higher following blastocyst transfer (58.33%), when compared with early stage blastocyst (53.85%; P = 0.554) and cavitating morula transfers (34.40%; P < 0.001). Implantation was higher when the female partner age was ≤35 years when compared with >35 year age group (52.75 versus 35.44%; P = 0.008).

LIMITATIONS, REASONS FOR CAUTION

A potential limitation of this study is that it is cross-sectional. Generally in such studies more than one variable could affect the outcome. Analyzing sperm is one part of the equation but a number of environmental and female factors also have the potential to influence embryo development and implantation. Furthermore, the selection of morphologically normal and physiologically motile sperm may result in isolation of sperm with reduced DNA damage. Therefore, selecting the best available sperm for ICSI may lead to experimental bias, as the selected sperm do not represent the overall sperm population in which the DNA damage is measured. Similar studies on selected sperm and with a larger sample size are now required.

WIDER IMPLICATIONS OF THE FINDINGS

The paternal influence of damaged chromatin is more prominent after zygotic transcriptional activation. A prolonged paternal effect on the developing embryo may be due to the active repair mechanism present in oocytes that tends to overcome the damaged paternal chromatin. The probability of eliminating an embryo fertilized by a sperm with damaged DNA is higher at the blastocyst stage than the cleavage stage; therefore blastocyst transfer could be recommended for better implantation success. Finally, we recommend ICSI treatment for patients with a higher percentage of sperm with DNA damage as well as additional studies with a larger sample size aimed at assessing DNA damage analysis as a diagnostic tool for IVF.

STUDY FUNDING/COMPETING INTERESTS

This work was supported by the University of Utah internal funds. The authors declare no competing interests.

TRIAL REGISTRATION NUMBER

N/A.

Sperm morphological abnormalities visualised at high magnification predict embryonic development, from fertilisation to the blastocyst stage, in couples undergoing ICSI

PURPOSE

To investigate the predictive value of the motile sperm organelle morphology examination (MSOME) on embryo morphology.

METHODS

The morphologies of 540 embryos obtained from 60 couples undergoing ICSI were evaluated from days 1 to 5 of development and were examined for associations with the percentages of morphologically normal paternal sperm and of the paternal sperm with large nuclear vacuoles (LNVs) as determined by MSOME.

RESULTS

An increased percentage of LNV sperm was associated with increased odds of a zygote presenting with pronuclear abnormalities. It was also associated with decreased odds of (i) normal cleavage on days 2 and 3 of development, (ii) the presence of a high-quality embryo on day 3, (iii) the development of an embryo to the blastocyst stage, and (iv) an embryo possessing a normal trophectoderm and inner cell mass. The calculated areas under the curves differed for the embryos that did and did not develop to the blastocyst stage and for the high- and low-quality blastocysts. The optimal cut-off value for the percentage of LNV sperm that maximised proper blastocyst formation was ≤24.5 %, and the cut-off value that maximised blastocyst quality was ≤19.5 %.

CONCLUSIONS

These results suggest a very early onset of paternal influences on embryo development. The evaluation of the incidence of vacuoles by MSOME may significantly improve upon the prognostic information provided by conventional semen analyses.

The usefulness of Real Time Morphology software in semen assessment of teratozoospermic boars

The aim of the present study was to compare two different techniques of sperm cell morphology evaluation in teratozoospermic boars: computer assisted semen morphology analysis and conventional assessment of stained semen smears. The semen samples were collected manually from 30 boars with reduced semen quality. In all samples the percentage of morphologically normal spermatozoa was below 70%. Computer assisted semen morphology assessment was performed using the Real Time Morphology (RTM) software (IVOS ver. 12.2, Hamilton Thorne Bioscience). The assessment was made by phase contrast optics, with the magnification of 20 x 3.8 and without staining. Conventional morphology assessment was performed by bright field microscopy with 1,000 x magnification after staining with Giemsa. At least 200 spermatozoa were evaluated per slide in both methods. The Bland-Altman plot indicated a general agreement between both methods of sperm morphology evaluation. The plots revealed the widest limits of agreement (mean ± 1.96 SD) for the percentage of midpiece anomalies (from -16 to 13.2), and the narrowest for the percentage of looped tail (from -1.49 to 1.09). The Bland Altman plot indicates general agreement between RTM and Giemsa staining in the percentage of major and minor defects. However, it was not possible to evaluate acrosomes using RTM. Otherwise, RTM proved to be a valuable tool in sperm morphology assessment, with accuracy equal to typical conventional methods.

Sperm chromatin integrity may predict future fertility for unexplained recurrent spontaneous abortion patients

The pathogenesis of recurrent spontaneous abortion (RSA) is multi-factorial, complex and poorly understood. In the present study, semen parameters, including sperm chromatin integrity, sperm concentration, sperm motility and sperm morphology, were compared between 111 men whose partners had a history of unexplained RSA (RSA group) and 30 healthy fertile men (control group). The RSA group was further separated into three subgroups, depending on their reproductive outcome during the 12 months after they were enrolled in the study: the pregnancy subgroup consisted of 43 men whose partners achieved a successful pregnancy up to at least the 24th week of gestation; the abortion subgroup included 31 men whose partners experienced further abortions; and the infertile subgroup had 37 men whose partners did not have any positive pregnancy test after regular, unprotected intercourse. Significantly lower proportion of sperm with normal morphology was found in the abortion subgroup (14.7 ± 4.3%) than in the control group (17.5 ± 5.0%). Sperm concentrations were significantly lower in the infertile subgroup (55.7 ± 24.1%) than in the controls (68.6 ± 27.8%). The rates of abnormal sperm chromatin integrity were significantly higher in the abortion (16.7 ± 7.7%) and infertile (16.3 ± 6.6%) subgroups, compared to the control group (13.0 ± 4.4%). Logistic regression analysis showed that the subsequent reproductive outcome of the 111 RSA patients was negatively correlated to the rates of abnormal sperm chromatin integrity. In conclusion, sperm chromatin integrity, sperm morphology, and sperm concentration were associated with future reproductive outcome of RSA patients. The sperm chromatin integrity was a significant predictor for future abortion and infertility.

Poor sperm quality and advancing age are associated with increased sperm DNA damage in infertile men

With increasing evidence for faulty paternal contribution to reproduction, there has been a steady increase in studies highlighting an association between sperm DNA damage, failed/delayed fertilisation and aberrant embryo development. Owing to prevailing ambiguity, the aims of the study were to analyse the genetic integrity of the male gamete and then to understand its association with age, standard semen parameters, lifestyle and occupational factors. The study included 504 subjects, attending university infertility clinic for fertility evaluation and treatment. Semen characteristics were analysed by standard criteria; terminal deoxynucelotidyl transferase-mediated nick end-labelling assay was employed for DNA damage assessment. The average incidence of sperm DNA damage in patients with normozoospermic semen parameters was <10%. Patients with oligozoospermia, severe oligozoospermia, oligoasthenoteratospermia, asthenoteratozoospermia and necrozoospermia had significantly higher level of sperm DNA damage (P < 0.001). Patients above 40 years of age had significantly high levels of DNA damage (P < 0.001) compared with their counterparts. Patients with varicocele and a history of alcohol consumption had higher incidence of spermatozoa with DNA damage (P < 0.01). Poor sperm characteristics in the ejaculate are associated with increased sperm DNA damage. Age-related increase in sperm DNA damage and association of the same with varicocele and alcohol consumption are also demonstrated.

Diagnostic significance of sperm-zona pellucida interaction

Spermatozoa binding to the zona pellucida is an early, critical event leading to fertilization and early pre-embryo development. Fertilization involves a complex and orderly sequence of events that is completed at syngamy, which is defined as the union of the two sets of haploid chromosomes to form a new diploid fertilized ovum (zygote). In order to be able to fertilize an oocyte, spermatozoa need to undergo a process called ‘capacitation’, which is usually defined as a series of changes that renders the sperm cells capable of undergoing the acrosome reaction. This process that naturally occurs within the female genital tract is possible under in vitro conditions. However, capacitation is not the only process spermatozoa must undergo to fertilize the oocytes successfully. To fertilize an oocyte, spermatozoa must also be at least highly motile, as well as being capable of undergoing the acrosome reaction timely, penetrating through the oocyte investments and fusing with the oocyte plasma membrane properly.

Fresh and frozen-thawed sperm quality, nuclear DNA integrity, invitro fertility, embryo development, and live-born offspring of N-ethyl-N-nitrosourea (ENU) mice

Efficient collection, freezing, reliable archiving of sperm, and re-derivation of mutant mice are essential components for large-scale mutagenesis programs in the mouse. Induced mutations (i.e. transgenes, targeted mutations, chemically induced mutations) in mice may cause inherited or temporary sterility, increase abnormal sperm values, or decrease fertility. One purpose of this study was to compare the effect(s) on fresh and frozen-thawed sperm quality, spermatozoa DNA integrity, unassisted in vitro fertility (IVF) rate, in vitro embryo development rate to blastocysts, and live-born offspring rates in non-ENU (control) animals and the F1-generation of N-ethyl-N-nitrosourea (ENU)-treated male mice (765mg/kg C57BL6/J or 600mg/kg 129S1/SvImJ total dose). The second purpose was to determine the effect(s) of parental oocyte donor strain on in vitro fertilization, in vitro embryo development to blastocysts, and live-born offspring rates using sperm and unassisted IVF to re-derive animals from non-ENU control and ENU mice. Sperm assessment parameters included progressive motility, concentration, plasma membrane integrity, membrane function integrity, acrosome integrity, and DNA integrity. There were no significant differences in fresh sperm assessment parameters, DNA integrity, unassisted in vitro fertility rate, in vitro embryo development rate to blastocysts, and live-born offspring rates between non-ENU and C3B6F1/J or B6129S1F1/J ENU mice. In addition, there were no significant differences in frozen-thawed sperm assessment parameters and DNA integrity rates for non-ENU control and ENU C3B6F1/J or B6129SF1/J mice. In vitro fertilization and in vitro embryo development to blastocysts were effected from strain genetic variability (P<0.05). However, the cryopreservation process caused an increase of DNA fragmentation in non-ENU control and ENU C3B6F1/J or B6129S1F1/J hybrid mice compared to fresh control sperm (P<0.01). Unlike the combinations of hybrid sperm and hybrid oocyte, increasing frozen-thawed sperm DNA fragmentation decreased the embryo development rate to blastocyst compared to fresh sperm when C57BL6, C3H, or 129S inbred mice were used as oocyte donors (P<0.05).

Determination of new types of DNA lesions in human sperm

Careful attention has been focused recently on DNA quality in human IVF. Therefore a variety of methods has been developed to evaluate DNA integrity, especially concerning fragmentation. Using liquid chromatography and mass spectrometry (LC/MS/MS) for our best sperm samples, we have established reference values for several oxidative lesions, in order to gain insights into the cause of DNA lesions. Besides 8-oxodeoxyguanosine, we found rather high levels of two ethenonucleosides: 1,N6-ethenoadenosine and 1,N2-ethenoguanosine. These compounds probably arise from a reaction with 4-hydroxy-2-nonenal, the main aldehyde compound released during lipid peroxidation, or after occupational exposure to vinyl chloride. The quantity of chlorinated bases detected is low. All of this decay has to be repaired by the oocytes at the time of fertilization or immediately after. This aspect should not be overlooked in assisted reproductive technology, in order to understand risks and limitations.

Is abnormal sperm function an indicator among couples with recurrent pregnancy loss?

OBJECTIVE

To determine whether or not sperm function parameters are altered in male partners of couples with a history of idiopathic recurrent pregnancy loss (RPL).

DESIGN

In comparison with proven fertile volunteers, sperm function parameters like hypo-osmotic swelling (HOS), acrosomal status (AS), and nuclear chromatin decondensation (NCD) were assessed in vitro from male partners of couples with a history of idiopathic RPL.

SETTING

Infertility clinic and andrology laboratory at National Institute of Health and Family Welfare.

PATIENT(S)

Male partners of couples with a history of idiopathic RPL and proven fertile male volunteers (control).

INTERVENTION(S)

Standard semen analysis, assessment of sperm morphology, and sperm function with tests such as HOS, AS, and NCD.

MAIN OUTCOME MEASURE(S)

Sperm paameters, such as HOS, AS, and NCD, were assessed in semen samples from RPL in comparison with the proven fertile control group.

RESULT(S)

Semen samples from the idiopathic RPL group showed below normal test scores in 57.1% of the cases for all three sperm parameters. The highest aberration (83% of cases) in sperm attributes was observed in NCD, followed by AS (45.7%) and HOS (42.9%). In contrast, abnormality in sperm morphology was limited to 5.7% of the cases. Subnormal sperm function is directly proportional with subnormal sperm motility (<50%) in 23% of the cases. Even in semen samples with normal sperm motility, sperm function scores were below normal in 31.4% of the RPL group.

CONCLUSION(S)

Reduction in test scores of sperm function, like HOS, AS, and NCD, in male partners of couples with idiopathic RPL suggests that sperms with altered or lowered functional competencies, if they fertilize the oocytes, may lead to the development of an unsustainable embryo resulting in early pregnancy loss. Normal sperm motility does not always ensure normal sperm function scores.

APEX/Ref-1 (apurinic/apyrimidic endonuclease DNA-repair gene) expression in human and ascidian (Ciona intestinalis) gametes and embryos

In recent years, the impact of sperm DNA damage on fertility has become an important issue. The different technologies developed to check sperm DNA fragmentation lead to the same conclusion: DNA damage negatively impacts upon reproductive processes. Oocyte DNA repair capacity is one of the cues to understanding embryo developmental arrest. APEX/Ref-1 (apurinic/apyrimidic endonuclease) is an enzyme involved in the DNA base excision repair pathway removing the abasic sites, the most common DNA decays. In humans, APEX has a multifunctional role, including the control of the redox status of transcription factors. RT-PCR allowed us to detect human APEX transcripts in oocytes, spermatozoa and preimplantation blocked embryos. In parallel, a comparative study on sea squirt Ciona intestinalis (ascidian) indicated that APEX transcripts are clearly detectable in oocytes and embryos until the larva stage, but not in spermatozoa, suggesting the appearance of the paternal contribution to DNA repair during development having arisen only late in Vertebrate evolution. Of additional phylogenetic significance is the observation that sea squirt APEX appears to lack redox transcriptional activity.

Effects of cryopreservation on sperm quality, nuclear DNA integrity, in vitro fertilization, and in vitro embryo development in the mouse

Efficient freezing, archiving, and thawing of sperm are essential techniques to support large scale research programs using mouse models of human disease. The purpose of this study was to investigate the effects of variable combinations and concentrations of cryoprotectants on sperm-assessment parameters of frozen–thawed mouse sperm in order to optimize cryopreservation protocols. Sperm was frozen using combinations of 3% skim milk + 0.2 or 0.3 M nonpermeating raffinose with either permeating glucose, fructose, propylene glycol, ethylene glycol, glycerol, or sodium pyruvate in CD-1, C3FeB6F1/J, B6129SF1, C57BL/6NCrIBR, 129S/SvPaslco, and DBA/2NCrIBR mice. Sperm-assessment parameters included progressive motility, plasma membrane integrity (SYBR-14 + PI),in vitrofertilization rate, andin vitroembryo development rate to blastocyst. DNA content analysis of sperm was measured by the sperm chromatin structure assay (SCSA). 0.3 M raffinose with 0.1 M fructose significantly improved post-thaw sperm-assessment parameters for CD-1, C3B6F1, B6129SF1 mice (P< 0.05–0.01), whereas 0.2 M raffinose with 0.1 M glycerol or 0.1 M fructose enhanced sperm assessment values for C57BL/6 and 129S mice (P< 0.01), compared to 0.3 M raffinose alone. DNA fragmentation during cryopreservation was significantly increased in all strains evaluated when compared with fresh control sperm in a strain-dependent manner (P< 0.01). Supplementation with permeating glycerol or fructose to the cryoprotectant (CPA) solution showed a significant protective effect to DNA integrity when cryopreserving sperm from C57BL/6 and 129S mice. Damage to sperm DNA significantly decreased the rate ofin vitroembryo development to blastocyst in C57BL/6 mice. The type of monosaccharide sugar or polyols, CPA molarity, and combination of permeating and nonpermeating cryoprotectant are significant factors for improving progressive motility, plasma membrane integrity, DNA integrity,in vitrofertilization rate, andin vitroembryo development rate to blastocyst in cryopreserved mouse sperm.

Paternal and maternal factors in preimplantation embryogenesis: interaction with the biochemical environment

Paternal effect on embryonic development occurs as early as fertilization. Incorrect formation of the spermatozoon due to centrosome defects and abnormal concentrations of any components involved in the activation process lead to failure immediately or in the subsequent cell cycles. Sperm chromosomal abnormalities result in early embryo developmental arrests. Generally poor spermatozoa lead to poor blastocyst formation. Sperm DNA fragmentation may impair even late post-implantation development. The DNA repair capacity of the oocytes is of major importance. Early preimplantation development, i.e. until maternal to zygotic transition, is maternally driven. Maternal mRNAs and proteins are of major importance, as there is an unavoidable turnover of these reserves. Polyadenylation of these mRNAs is precisely controlled, in order to avoid too early or too late transcription and translation of the housekeeping genes. An important set of maternal regulations, such as DNA stability, transcriptional regulation and protection against oxidative stress, are impaired by age. The embryo biochemical endogenous pool is very important and may depend upon the environment, i.e. the culture medium. Paternal, maternal and environmental factors are unavoidable parameters; they become evident when age impairs oocyte quality.

The effects of sperm quality on embryo development after intracytoplasmic sperm injection

PURPOSE

To explore the possible relationship between sperm quality and embryo development, pregnancy and implantation rates, in patients undergoing intracytoplasmic sperm injection (ICSI).

METHODS

Fertilization and cleavage rates, quality of embryos, blastocyst development, pregnancy and implantation rates were analyzed in 1020 embryos from 219 couples undergoing first ICSI treatment cycle. The couples were allocated in five groups, according to semen parameters: Group 1: patients with normal semen parameters, Group 2: patients with mild oligo-astheno-teratozoospermia, Group 3: patients with severe oligo-astheno-teratozoospermia, Group 4: patients with obstructive azoospermia, Group 5: patients with non-obstructive azoospermia.

RESULTS

Fertilization and cleavage rates, quality of embryos as well as blastocyst development rates were significantly reduced, as semen quality decreased. However, no significant differences were observed in clinical pregnancy and implantation rates.

CONCLUSION

Overall, a negative relationship was observed between semen quality and embryo development, even before activation of the embryonic genome, suggesting that sperm can affect embryogenesis from a very early stage.

La fragmentation de l'ADN du spermatozoïde : impact en Assistance médicale à la procréation

We have used the sperm chromatin structure assay (SCSA) test in order to determine if correlations can be found between sperm DNA fragmentation and spermogram parameters. Only necrospermia and DNA fragmentation index are strongly correlated (P<0.0001). Neither fertilization rates for ICSI and IVF, nor blastocyst formation rates are impaired by a high DFI. However when the critical DFI>30% is reached, the chances of having ongoing pregnancies after blastocyst transfer are reduced by three. Treatments with antioxidants are of limited efficacy even though we obtained 2 deliveries after DFI treatments with such treatments. New strategies in order to improve the pregnancy rates for these peculiar cases of reduced fertility are discussed.

Seminal elastase-inhibitor complex, a marker of genital tract inflammation, and negative IVF outcome measures: role for a silent inflammation?

There is no consensus on whether and how male genital tract inflammation affects sperm fertilizing potential. The aims of this prospective study were to evaluate the elastase-inhibitor complex in seminal plasma (s-EI) level, a marker of male genital tract inflammation, in men undergoing in vitro fertilization (IVF) having no clinical signs of inflammation, and its association with semen characteristics, and the predictive role of s-EI for the outcome of IVF in terms of fertilization, embryo development to the blastocyst stage and pregnancy. The study involved 104 male partners of infertile couples with normal spermiogram undergoing IVF. On the day of oocyte retrieval, spermiogram and s-EI assessment using homogeneous immunoassay were performed. The outcome of IVF according to the s-EI level was assessed in 85 cycles with two or more oocytes. In 67 cycles embryos were cultured to the blastocyst stage. Spearman's and Pearson's correlation tests, chi-square test, and multiple linear and logistic regression analyses were used for statistical evaluation. Increased s-EI level (> or =250 microg/L) was detected in semen of 32% of men, and in 24% of men without leucocytospermia. We found an association between the s-EI level and semen leucocytes (r = 0.49, p = 0.004) but not with classical sperm characteristics. No correlation between the s-EI level and fertilization was observed. Increased s-EI levels were associated with a poorer blastocyst development rate (p = 0.03) and a higher number of arrested embryos (p = 0.04). Extended embryo culture to the blastocyst stage shows a negative effect of clinically silent male genital tract inflammation on embryo developmental potential.

Effect of PGD on implantation and ongoing pregnancy rates in cases with predominantly macrocephalic spermatozoa

Although its occurrence is rare, the presence of large headed or macrocephalic spermatozoa and increased chromosomal abnormality has recently been reported by several groups. Moreover, when intracytoplasmic sperm injection (ICSI) was performed with samples containing macrocephalic spermatozoa, lower fertilization and implantation rates result in poor clinical outcome. In order to evaluate the impact of preimplantation genetic diagnosis (PGD) on implantation and ongoing pregnancy rates in these couples, the results of 23 PGD cycles were compared with non-PGD cycles (n = 60) as well as cycles with absolute teratozoospermia (having zero normal morphology) with (n = 14) or without PGD (n = 66). Out of 82 embryos biopsied in the macrocephalic sperm group, abnormalities were detected in 46.4% of the embryos analysed. Most of the abnormalities were trisomies (37.0%) and complex aneuploidies (51.9%). A 33.3% pregnancy rate was achieved by selectively transferring euploid embryos after PGD with the statistically higher implantation rate of 25.0% compared with non-PGD cycles (IR: 12.3%, P < 0.01). Moreover, only one missed abortion (14.3%) was observed in the PGD group, whereas seven of the 15 pregnancies resulted in abortion in the non-PGD group (46.7%). Preliminary results indicate that patients should be counselled for increased chromosomal abnormality and a possible beneficial effect of eliminating chromosomally abnormal embryos with PGD on a bortion rates.

Seminal reactive oxygen species as predictors of fertilization, embryo quality and pregnancy rates after conventional in vitro fertilization and intracytoplasmic sperm injection

High seminal reactive oxygen species (ROS) are related to poor semen quality and impaired fertilization. We aimed at finding whether there is an association between ROS and fertilization, embryo quality and pregnancy rates after conventional in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI). In prepared semen of 147 male partners of infertile couples, ROS were assessed with luminol chemiluminescence. Spermiogram was assessed in native semen. ROS were negatively correlated with standard sperm characteristics and testicular volume, and positively with abnormal sperm head morphology. Fertilization rate and embryo morphology on day 2 and on day 4 were assessed in 41 IVF and 106 ICSI cycles. The influence of maternal (female age and number of oocytes) and paternal (sperm motility, morphology and ROS) factors on fertilization and embryo quality were assessed by means of regression analyses. After IVF, fertilization and pregnancy rates were negatively associated with ROS level (p = 0.031 and 0.041, respectively). In case of higher ROS, significantly fewer ICSI-derived embryos (p = 0.036) reached the morula-blastocyst stage on day 4. High seminal ROS levels are associated with impaired sperm fertilizing ability and lower pregnancy rates after IVF. In ICSI, a negative association of ROS with embryo development to the blastocyst stage has been observed.

Influence of oocytes and spermatozoa on early embryonic development

OBJECTIVE

To evaluate the effect of oocytes and spermatozoa on early embryonic development.

DESIGN

Retrospective study.

SETTING

Infertility Clinic, the Family Federation of Finland.

PATIENT(S)

Fifty-nine oocyte donation cycles with oocytes shared among 118 recipient couples.

INTERVENTION(S)

Culture of all fertilized oocytes.

MAIN OUTCOME MEASURE(S)

Standard sperm (concentration, progressive motility, and morphology according to Tygerberg strict criteria) and embryo (morphology and cleavage stage) characteristics.

RESULT(S)

A marked effect of the oocyte on both embryo morphology and blastomere cleavage rate was demonstrated. In addition, a significant sperm effect on blastomere cleavage rate was found. Sperm morphology as determined according to strict criteria rather than sperm count or progressive motility was positively associated with the blastomere cleavage rate. None of the measured sperm characteristics influenced embryo morphology.

CONCLUSION(S)

Embryo morphology, i.e., fragmentation and blastomere uniformity, are predominantly determined by oocyte quality, whereas both the oocyte and spermatozoa influence the blastomere cleavage rate.

Sperm single-stranded DNA, detected by acridine orange staining, reduces fertilization and quality of ICSI-derived embryos

PURPOSE

The aim of this study was to evaluate the effect of sperm single-stranded DNA, detected by acridine orange (AO), and classical sperm parameters on embryonic quality after ICSI.

METHODS

Before ICSI, the spermatozoa of 183 infertile patients with oligo-, astheno-, teratozoospermia (n = 147), or more than one previous unsuccessful conventional IVF attempt (n = 36) were stained by AO to assess the presence of single-stranded DNA. Two days after ICSI, the embryos of 135 patients were scored for morphology, fragmentation included. Embryos of 48 couples were cultured for 4 days to develop to the morula or blastocyst stage. At most 2 embryos were transferred on Day 2 or 4.

RESULTS

When the level of spermatozoa with single-stranded DNA was increased, there was a significantly lower fertilization rate after ICSI. Besides, increased sperm single-stranded DNA resulted in a higher proportion of heavily fragmented embryos on Day 2 (P < 0.05). In patients with an increased level of spermatozoa with single-stranded DNA, a significantly higher number of embryos were arrested in spite of prolonged culturing (P < 0.05). Classical sperm parameters did not affect the quality and developmental potential of ICSI-derived embryos. No correlation was found between the level of spermatozoa with single-stranded DNA, pregnancy rate, and live-birth rate achieved by ICSI, except in patients with 0% of spermatozoa with single-stranded DNA, in whom the pregnancy rate was significantly higher.

CONCLUSIONS

Sperm single-stranded DNA provides additional data on sperm functional capacity in terms of fertilization and embryonic quality after ICSI.

Possible consequences of performing intracytoplasmic sperm injection (ICSI) with sperm possessing nuclear DNA damage

A number of studies have confirmed that sperm with damaged nuclear DNA are present in human ejaculate. It appears that these sperm are more likely to occur in men with low concentrations of sperm, or poor sperm motility or morphology. In assisted reproductive techniques, in particular intracytoplasmic sperm injection (ICSI), there is a higher statistical chance that sperm possessing damaged DNA will be selected and used to fertilize oocytes. In light of this observation, the question of whether human sperm with damaged DNA can impair fertilization and embryo development is examined.

Defective sperm decondensation: a cause for fertilization failure

The study aimed to evaluate the role of chromatin packaging (CMA3 staining), sperm morphology during sperm-zona binding, sperm decondensation and the presence of polar bodies in oocytes that failed in vitro fertilization (IVF). The percentage CMA3 staining categorized the data into three groups, < 44%, n = 10; > or = 44-59%, n = 10; and > or = 60%, n = 29. Morphology groups were < or = 4% (n = 11); > 4-14% (n = 19); and > 4% (n = 19). One hundred and seventy-two oocytes that failed IVF were evaluated for sperm-zona binding, ooplasma penetration and sperm decondensation. Odds ratio analyses indicated that being in the > or = 60% CMA3 staining group resulted in a 15.6 fold increase in the risk of decondensation failure, relative to CMA3, staining of < 44%. For morphology, there was a 2.17 fold decrease in the risk of fertilization failure in the morphology group with > 4-14% normal cells, while it increased 2.45 fold for the morphology group with < or = 4% normal cells. Using CMA3 fluorescence to discriminate, 51% of the oocytes in the group with elevated CMA3 fluorescence had no sperm in the ooplasma compared to 32% and 16% penetration failure in the CMA3 staining groups > or = 44-59% and < 44%, respectively. Sperm chromatin packaging quality and sperm morphology assessments are useful clinical indicators of human fertilization failure. Immunofluorescence techniques could be used to provide a clear diagnosis of failed fertilization.

The outcome of intracytoplasmic injection of fresh and cryopreserved ejaculated spermatozoa--a prospective randomized study

BACKGROUND

The overall aim of this prospective, randomized study was to compare the reproductive potential of fresh and frozen-thawed ejaculated spermatozoa from oligoasthenoteratozoospermic patients in an intracytoplasmic sperm injection (ICSI) procedure.

METHODS

All patients consenting to participate in this study had a sperm sample frozen prior to the start of a cycle. Patients were randomized using a random number table to undergo ICSI with either fresh (group A, n = 118) or frozen-thawed (group B, n = 122) spermatozoa. All prognostic variables were equally distributed among the two groups.

RESULTS

The pregnancy rate per started cycle was 29.7% in group A and 38.5% in group B, P > 0.05. A significant difference was observed in the rate of ongoing pregnancies between group A (23.7%) and group B (35.2%), P < 0.05.

CONCLUSION

From our data we can conclude that cryopreservation of spermatozoa from men with poor sperm quality does not negatively affect fertilization and pregnancy rates after ICSI. A larger study will be needed to investigate whether the use of cryopreserved spermatozoa can be helpful in selecting the most vital spermatozoa for ICSI.

Acrosome index is not an absolute predictor of the outcome following conventional in vitro fertilization and intracytoplasmic sperm injection

PURPOSE

To investigate if including evaluation of acrosome index (AI) in the semen analysis of teratozoospermic samples could help to predict for which patients intracytoplasmic sperm injection (ICSI) is necessary.

METHODS

The fertilization rate, pregnancy rate, and percentage of good quality embryos were compared after performing conventional in vitro fertilization (IVF) and ICSI, respectively, using sibling oocytes. The role of AI was evaluated by dividing patients into two groups; Group A (AI < 7%) and Group B (AI > or = 7%).

RESULTS

A significant difference in fertilization rate was observed between Group A and B after conventional IVF. In Group A, the fertilization rate, embryo transfer rate, and percentage of good quality embryos were higher after ICSI than after IVF. In Group B, the fertilization and pregnancy rates were numerically but not significantly higher after IVF compared to ICSI.

CONCLUSION

Evaluation of acrosome index will not accurately predict fertilization, although this study shows that a sperm sample with less than 5% normal forms and an AI greater than 7% may achieve a mean fertilization rate > 70% after conventional IVF.

Outcome of intracytoplasmic sperm injection in azoospermic patients: stressing the liaison between the urologist and reproductive medicine specialist

OBJECTIVES

To analyze the outcome of intracytoplasmic sperm injection (ICSI) cycles in infertile couples in whom the main diagnosis of infertility was azoospermia of obstructive and nonobstructive origin.

METHODS

Eighty-three consecutive ICSI cycles were carried out with retrieved testicular or epididymal spermatozoa, 60 cycles in 32 patients with obstructive azoospermia and 23 cycles in 12 patients with nonobstructive azoospermia. Fifty-four testicular biopsies (testicular sperm extraction) and 18 epididymal aspirations (microepididymal sperm aspiration) were performed.Results. Motile spermatozoa were recovered in 65 cycles (90.3%). In another 3 (4.2%), nonmotile spermatozoa were retrieved. In 4 patients (5.5%), sperm could not be recovered. In 11 cycles, frozen sperm from a previous procedure were used. A significantly lower fertilization rate (64% versus 73%, P = 0.02), clinical pregnancy rate (13% versus 47%, P <0.001), and good embryo quality rates (35% versus 56%, P = 0.009) were observed in patients with nonobstructive azoospermia. In patients with obstructive azoospermia, no significant differences were observed when the outcome was analyzed on the basis of the sperm origin (ie, from testicular sperm extraction or microepididymal sperm aspiration).

CONCLUSIONS

When combining testicular sperm extraction or microepididymal sperm aspiration with ICSI in patients with obstructive azoospermia, the results in terms of fertilization, implantation, and pregnancy rates were similar to those found in patients with nonazoospermic obstruction who underwent ICSI with ejaculated sperm. Patients with nonobstructive azoospermia had lower fertilization, embryo quality, and pregnancy rates than did those with obstructive azoospermia, probably because of severe defects in spermatogenesis, leading to poor gamete quality. The urologist and reproductive endocrinologist now have an excellent therapeutic option to offer men with previously intractable infertility.

The effect of intracytoplasmic sperm injection and semen parameters on blastocyst development in vitro

The present study compares the development and quality of blastocysts derived from conventional oocyte insemination with those derived from intracytoplasmic sperm injection (ICSI). Oocytes were collected from patients undergoing ovarian stimulation with human menopausal gonadotrophins for IVF. Patients with normal semen were assigned to conventional oocyte insemination while those with progressive motility <20% and/or normal sperm morphology < or =4% were assigned to ICSI. Resulting embryos were cultured for up to 6 days. The mean number and percentage of embryos reaching the blastocyst stage and the mean number and percentage of blastocysts of high quality on days 5-6 were assessed for both treatment groups and compared. The influence of paternal factors (sperm concentration, motility, progressive motility, morphology) on blastocyst development and quality were assessed by regression analyses. Significantly more ICSI-derived embryos arrested at the 5- to 8-cell stage (P = 0.024) concomitant with the activation of the paternal genome than those derived from conventional oocyte insemination. Significantly fewer ICSI-derived embryos reached the blastocyst stage on days 5-6 (P<0.001) and significantly fewer ICSI-derived embryos were of high quality (P = 0.002) compared with conventional oocyte insemination. When treatment groups were combined and evaluated by regression analysis, progressive motility and sperm morphology were significantly correlated with diminished blastocyst development and quality (P < 0.05). From these data, we conclude that paternal factors and/or performing ICSI in cases of severe male factor infertility may have a detrimental effect on blastocyst development and their quality.

Blastocyst transfer following intracytoplasmic injection of ejaculated, epididymal or testicular spermatozoa

Recent studies indicate a strong paternal influence on embryo development and progression of the embryo to the blastocyst stage. The aim of this study was to compare, during extended culture, the in-vitro development of embryos resulting from intracytoplasmic sperm injection (ICSI) of ejaculated spermatozoa (group 1, n = 347), epididymal (group 2, n = 22) or testicular (group 3, n = 18) spermatozoa from obstructive azoospermic and testicular spermatozoa from non-obstructive azoospermic (group 4, n = 31) subjects. Fertilization and blastocyst formation rates were significantly lower in group 4 (P < 0.05). The incidence of expanded and hatching blastocysts was significantly lower in group 4 (P < 0.05). Overall in 93.2% ejaculate ICSI cycles, blastocysts were transferred on day 5. This was significantly higher than the 62% day 5 transfers in the non-obstructive azoospermic group (P < 0.05). Implantation rate per embryo was significantly higher in the ejaculate ICSI group compared with the other groups (P < 0.05). Clinical pregnancy per transfer was similar between groups; however, significantly fewer multiple pregnancies were encountered in the non-obstructive azoospermic group (P < 0.01). In conclusion, the source of the spermatozoa, most likely to be indicative of the severity of spermatogenic disorder, affects the rate of blastocyst formation and blastocyst implantation. Spermatozoa from non-obstructive azoospermic subjects, when utilized for ICSI, result in embryos that progress to the blastocyst stage at a lower and slower rate and implant less efficiently.

Poor quality of sperm as it affects repeated early pregnancy loss

A study was carried out to determine whether males contribute to repeated early pregnancy loss. Semen samples were analyzed from proven-fertile men (n = 51 group I) and from men whose partners presented with early pregnancy loss (>3 first trimester abortions, n = 32 group II). Routine analysis, sperm function tests, and ultrastructural studies of sperms were carried out. Female factor could be identified in 25 (78%) couples, and in 7 (22%) no cause either male or female could be identified and the semen analysis was normal. Percent morphologically normal did not differ significantly between the groups, but increased sperm head abnormalities were seen. The functional tests were all normal except for a significant decrease in the capacity of nuclear chromatin to decondense in vitro. The ultrastructural studies showed defects of chromatin condensation and irregular nuclei with vacuoles. This study points to the loss of chromatin integrity as a possible contributing factor from males to early pregnancy loss.

Does seminal fluid viscosity influence sperm chromatin integrity?

A retrospective study was undertaken to investigate whether viscosity alters sperm chromatin integrity. Semen samples were obtained from 269 men attending the infertility clinic. The viscosity was measured quantitatively by needle and syringe method and the viscosity ratio was calculated against distilled water. The chromatin integrity was evaluated by in vitro decondensation test using 1% SDS and 6 mM EDTA. According to the viscosity ratios the samples were divided into 2 groups: I, normal (ratio < 9, n = 239): and II, abnormal (ratio > 9, n = 30) viscosity. Chromatin integrity was significantly lower in the group with higher viscosity. Significant decrease in sperm count and motility were seen in group II as compared to group I. Thus, hyperviscosity of seminal fluid alters the sperm chromatin integrity.

Very low sperm count affects the result of intracytoplasmic sperm injection

PURPOSE

The aim was to examine the influence of extremely low sperm count on intracytoplasmic sperm injection (ICSI) outcome.

METHODS

Over 1000 consecutive unselected ICSI cycles were divided into four groups according to sperm concentration of their patients: A, cryptozoospermia, 107 patients; B, sperm concentration of < or = 1 x 10(4), 146 patients; C, sperm count of 1 x 10(4)-1 x 10(5), 135 patients; and concentration of > 1 x 10(5) and < 10 x 10(6)/ml (control group), 688 patients.

RESULTS

A significant decrease in pregnancy rate was noticed in the cryptozoospermic group in comparison to the control group (20% vs. 31%). Fertilization rate in group A was significantly lower in comparison to all other groups, respectively (46% vs. 52%, 54%, 61%). Embryo quality was inferior in group A in comparison to the control group. A higher yet not statistically significant abortion rate was observed in the cryptozoospermic group (as well as in group C) (30%, 27%) compared to the control group (15%).

CONCLUSIONS

It seems that an extremely low sperm count has a negative effect on the outcome of ICSI. Nevertheless patients with cryptozoospermia should not be offered ICSI treatment with the ejaculated sperm before karyotype is established.

Outcome of testicular sperm retrieval procedures in non-obstructive azoospermia: percutaneous aspiration versus open biopsy

The aim of this study was to evaluate whether the extraction of testicular spermatozoa with percutaneous versus open biopsy has an effect on the treatment outcome with intracytoplasmic sperm injection (ICSI) in men with non-obstructive azoospermia. Regardless of testicular size, follicle stimulating hormone concentration, and previous biopsy result, percutaneous testicular sperm aspiration (PTSA) using a 21-gauge butterfly needle was attempted first and if this failed testicular sperm extraction (TESE) was performed. In 63 men spermatozoa were found with PTSA whereas in 228 men TESE had to be undertaken. More men in the PTSA group had previously been diagnosed with hypospermatogenesis (82 versus 50%). Compared with the PTSA group, more men in the TESE group had germ cell aplasia (27 versus 10%) or maturation arrest (22 versus 8%). There was no difference between the groups regarding mean age of men and their partners, duration of stimulation, oestradiol concentration on the day of human chorionic gonadotrophin, number of oocytes retrieved, fertilization rate, and embryo quality between the two groups. The number of embryos transferred (4.38 versus 3.90) was significantly higher in the PTSA group (P < 0.05), reflecting the increased number of embryos available for transfer. Implantation rate per embryo was 20.7% in the PTSA and 13.3% in the TESE group (P < 0.05). Clinical pregnancy rates were 46 and 29% in the PTSA and TESE groups respectively (P < 0.05). Clinical abortion rates were similar (21.2 versus 24%). It is concluded that in men with non-obstructive azoospermia, easier sperm retrieval, which is most likely indicative of a more favourable histopathology, is associated with higher implantation rates per embryo.

Intracytoplasmic sperm injection increases embryo fragmentation without affecting clinical outcome

PURPOSE

To examine the effect of intracytoplasmic sperm injection (ICSI) on embryo fragmentation and implantation rates in those embryos chosen for transfer compared to conventional in vitro fertilization (IVF).

METHODS

We compared 253 infertility patients (71 ICSI and 182 IVF) with respect to age, semen analysis, number of embryos transferred, embryo fragmentation, implantation rate, and pregnancy rate. Embryo fragmentation was determined by one observer at the same laboratory over the entire study period.

RESULTS

A statistically significant difference was observed in mean embryo grade between IVF (2.2 +/- 0.84) and ICSI (2.5 +/- 0.77), P = 0.01. Additionally, the IVF patients had significantly more nonfragmented (grade I) embryos compared to the ICSI group, P < 0.01.

CONCLUSIONS

These data suggest that ICSI, irrespective of semen parameters, may increase embryo fragmentation and produce fewer nonfragmented grade I embryos while maintaining implantation and pregnancy rates similar to conventional IVF.