Micromanipulation of gametes for in vitro assisted fertilization

A brief history of technical developments in intracytoplasmic sperm injection (ICSI). Dedicated to the memory of J.M. Cummins

Intracytoplasmic sperm injection (ICSI) is an assisted reproductive technology for treatment of severe male infertility introduced into clinical practice in 1992. This review provides a brief history of the development of ICSI by acknowledging major developments in the field. The review addresses key developments in pre-clinical and early studies, how ICSI compares with in vitro fertilisation, long-term consequences, how the mechanistic approach to ICSI has changed in both manual and semi-automated approaches, and how sperm selection procedures are integrated into ICSI. From the beginnings using animal models in the 1960-1970s, the development of ICSI is a remarkable and transformative success story. Indeed, its broad use (70% of cycles globally) exceeds the need required for treating infertile males, and this remains a controversial issue. There remain questions around the long-term health impacts of ICSI. Furthermore, advances in automation of the ICSI procedure are occurring. An estimated 6million children have been born from the ICSI procedure. With further automation of sperm selection technologies, coupled with automation of the injection procedure, it is likely that the proportion of children born from ICSI will further increase.

Evolution of intracytoplasmic sperm injection: From initial challenges to wider applications

Background

In vitro fertilization (IVF) has revolutionized infertility treatment. Nevertheless, male infertility requires more effective solutions. In 1992, the first-ever case of human birth via intracytoplasmic sperm injection (ICSI) was reported. ICSI involves microscopically injecting a sperm into an ovum. Successful ICSI has become a reliable therapy for couples facing infertility, a significant milestone. However, it has also introduced various challenges. This study also delves into ethical dilemmas arising from widespread ICSI use.

Methods

This review traces the history of ICSI, presenting pioneering attempts, first successful attempts, and critical reports on account of the initial skepticism toward the technology. The review also focuses on chronological progress until ICSI was recognized as effective and became widely applied.

Main findings

The review reveals that ICSI, although transformative, presents challenges. Successes include addressing male infertility and aiding fertilization. However, concerns arise regarding optimal sperm and embryo selection, genetic mutations, and long-term health implications. Ethical considerations surrounding ICSI's broad applications also surface.

Conclusions

Despite its success and effectiveness, ICSI is still evolving as a therapeutic method. By comprehensively evaluating the historical progress and the current status of ICSI and exploring its future prospects, this study highlights the importance of ICSI in infertility treatment.

Intracytoplasmic sperm injection induces transgenerational abnormalities in mice

In vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI) are 2 major assisted reproductive techniques (ARTs) used widely to treat infertility. Recently, spermatogonial transplantation emerged as a new ART to restore fertility to young patients with cancer after cancer therapy. To examine the influence of germ cell manipulation on behavior of offspring, we produced F1 offspring by a combination of two ARTs, spermatogonial transplantation and ICSI. When these animals were compared with F1 offspring produced by ICSI using fresh wild-type sperm, not only spermatogonial transplantation-ICSI mice but also ICSI-only control mice exhibited behavioral abnormalities, which persisted in the F2 generation. Furthermore, although these F1 offspring appeared normal, F2 offspring produced by IVF using F1 sperm and wild-type oocytes showed various types of congenital abnormalities, including anophthalmia, hydrocephalus, and missing limbs. Therefore, ARTs can induce morphological and functional defects in mice, some of which become evident only after germline transmission.

Unlocking the Potential of Zebrafish Research with Artificial Intelligence: Advancements in Tracking, Processing, and Visualization

Zebrafish have become a widely accepted model organism for biomedical research due to their strong cortisol stress response, behavioral strain differences, and sensitivity to both drug treatments and predators. However, experimental zebrafish studies generate substantial data that must be analyzed through objective, accurate, and repeatable analysis methods. Recently, advancements in artificial intelligence (AI) have enabled automated tracking, image recognition, and data analysis, leading to more efficient and insightful investigations. In this review, we examine key AI applications in zebrafish research, including behavior analysis, genomics, and neuroscience. With the development of deep learning technology, AI algorithms have been used to precisely analyze and identify images of zebrafish, enabling automated testing and analysis. By applying AI algorithms in genomics research, researchers have elucidated the relationship between genes and biology, providing a better basis for the development of disease treatments and gene therapies. Additionally, the development of more effective neuroscience tools could help researchers better understand the complex neural networks in the zebrafish brain. In the future, further advancements in AI technology are expected to enable more extensive and in-depth medical research applications in zebrafish, improving our understanding of this important animal model. This review highlights the potential of AI technology in achieving the full potential of zebrafish research by enabling researchers to efficiently track, process, and visualize the outcomes of their experiments.

Past, present and future of ICSI in livestock species

During the past 2 decades, intracytoplasmic sperm injection (ICSI) has become a routine technique for clinical applications in humans. The widespread use among domestic species, however, has been limited to horses. In horses, ICSI is used to reproduce elite individuals and, as well as in humans, to mitigate or even circumvent reproductive barriers. Failures in superovulation and conventional in vitro fertilization (IVF) have been the main reason for the use of this technology in horses. In pigs, ICSI has been successfully used to produce transgenic animals. A series of factors have resulted in implementation of ICSI in pigs: need to use zygotes for numerous technologies, complexity of collecting zygotes surgically, and problems of polyspermy when there is utilization of IVF procedures. Nevertheless, there have been very few additional reports confirming positive results with the use of ICSI in pigs. The ICSI procedure could be important for use in cattle of high genetic value by maximizing semen utilization, as well as for utilization of spermatozoa from prepubertal bulls, by providing the opportunity to shorten the generation interval. When attempting to utilize ICSI in ruminants, there are some biological limitations that need to be overcome if this procedure is going to be efficacious for making genetic improvements in livestock in the future. In this review article, there is an overview and projection of the methodologies and applications that are envisioned for ICSI utilization in these species in the future.

Effectivity of conventional in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI) when male factor is absent: a perspective point of view

An objective and individualized approach of in vitro fertilization techniques tends to decrease costs and improve the experience of infertile couples during treatment. The use of available technologies to diagnose and treat infertility based on scientific evidence seems to be the best practice, which is the guideline that motivates this review on the available techniques for laboratory oocyte insemination. Conventional IVF, the pioneering technique, was initially used in the treatment of tubal obstruction infertility, successfully expanding the treatment of infertile couples presenting with several other factors. However, it was less effective in cases of severe male factor infertility. Intracytoplasmic sperm injection, which was developed in 1992, proved to be the method of choice for treating couples with severe male factor infertility. Since then, it has been increasingly used regardless of the infertility factor. This review discusses the effectiveness of conventional in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI) when the male factor is absent in all aspects, as technical and clinical outcomes, associated risks, adjustments for using with other technologies and costs. Finally we discuss the advantages and disadvantages of each one, with all aspects reviewed.

Evaluating the role of endometrial colour Doppler dynamic tissue perfusion measurements in in vitro fertilisation success

The role of uterine receptivity and endometrial perfusion in in vitro fertilisation (IVF) remains unclear. In our prospective pilot study, we used a new dynamic tissue perfusion measurement method to evaluate this relationship in humans. A standard ovulation induction and embryo transfer method were applied to all the volunteers. On the day of embryo transfer, dynamic images of the uterus were recorded using colour Doppler ultrasound, and these images were uploaded onto PixelFlux Chameleon Software (GmbH, Münster, Germany). After determining the region of interest (ROI), the average velocity, intensity, and area values for all coloured pixels in the ROI, the tissue resistance index (RI) and the tissue pulsatility index were calculated. Endometrial thickness, morphology and dynamic endometrial perfusion parameters were compared between the clinically pregnant and non-pregnant groups. Endometrial thickness, morphology values and endometrial dynamic tissue perfusion measurements were similar between the groups. This study compared perfusion parameters between clinically pregnant and non-pregnant patients by accurately calculating endometrial tissue perfusion using standard software to establish its relationship with implantation success in IVF treatment.IMPACT STATEMENTWhat is already known about this subject? The relationship between IVF success, endometrial receptivity and perfusion is known. Clear valuations of endometrial receptivity require an endometrial biopsy which may cause endometrial damage to the actual IVF cycle. This problem has led researchers to conduct non-interventional studies. Studies have revealed the value of endometrial thickness, pattern and Doppler examination of endometrial uterine arteries in predicting the success of IVF treatment.What do the results of this study add? This prospective pilot study is the first one to use this programme in humans to evaluate uterine receptivity in IVF. Successful results can be obtained by using computer programmes in tissues where perfusion parameters cannot be measured using traditional colour Doppler ultrasonography. Revealing the relationship between tissue perfusion and IVF success will be more effective and accurate with the development of software technologies.What are the implications of these findings for clinical practice and/or further research? To increase the success of IVF treatment, current and new technological developments, as well as imaging methods should continue to be tested.

A Review of Automated Microinjection of Zebrafish Embryos

Cell microinjection is a technique of precise delivery of substances into cells and is widely used for studying cell transfection, signaling pathways, and organelle functions. Microinjection of the embryos of zebrafish, the third most important animal model, has become a very useful technique in bioscience. However, factors such as the small cell size, high cell deformation tendency, and transparent zebrafish embryo membrane make the microinjection process difficult. Furthermore, this process has strict, specific requirements, such as chorion softening, avoiding contacting the first polar body, and high-precision detection. Therefore, highly accurate control and detection platforms are critical for achieving the automated microinjection of zebrafish embryos. This article reviews the latest technologies and methods used in the automated microinjection of zebrafish embryos and provides a detailed description of the current developments and applications of robotic microinjection systems. The review covers key areas related to automated embryo injection, including cell searching and location, cell position and posture adjustment, microscopic visual servoing control, sensors, actuators, puncturing mechanisms, and microinjection.

In vitro fertilization rate of horse oocytes with partially removed zonae

Frozen-thawed ejaculated stallion spermatozoa were preincubated for 3 h in BO medium containing 5 mM caffeine and then treated with 0.1 micro M calcium ionophore A23187 for 60 sec. Aliquots of the sperm suspension (final concentration 1-2 x 10(7)/ml) were added to the oocytes which had been matured in vitro for 32 h. In Experiment 1, there were 3 groups of oocytes; cumulus intact, denuded zona-intact, and zona-free. Cumulus cells were removed with 0.5% hyaluronidase and the zona pellucida with 0.1% protease. The oocytes were fixed 20 h after insemination with acetic acid:ethanol (1:3) and stained with 1% orcein. The sperm penetration rate of zona-free oocytes was 83%, whereas the sperm penetration rate was very low (1 to 3%) in the cumulus-enclosed or zona-intact oocytes. In Experiment 2, denuded zona-intact oocytes were placed in PBS supplemented with 10% fetal bovine serum 1 h before the end of in vitro maturation. The zona pellucida was micromanipulated with a metal microblade under x 100 magnification within 20 min of treatment with 0.3 M sucrose. For partial zona dissection, a slit in the zona pellucida was made. For partial zona removal, oocytes were transferred to protein-free PBS to fix the oocytes on the bottom of the Petri-dish and to remove a piece of the zona pellucida. Micromanipulated oocytes were subjected to in vitro fertilization as described above. Zona-intact and zona-free oocytes treated with sucrose solution for 20 min were used as controls. The penetration rates were 4 (2/57), 12 (7/58), 52 (31/60), and 86% (44/51) for zona-intact, partially zona dissected, partially zona removed, and zona-free oocytes, respectively. Proportions of oocytes with monospermic penetration were 100 (2/2), 57 (4/7), 58 (18/31), and 34% (15/44), respectively. In Experiment 3, sperm penetration and male pronucleus formation in the partially zona removed oocytes were examined at 2.5 to 20.0 h of insemination. Sperm penetration started 2.5 h post-insemination (22%, 11/49), and increased to 38% (21/55) at 5 h, to 46% (23/50) at 10 h, and to 56% (27/48) at 20 h. The transformation of sperm heads into male pronuclei was first observed 10 h post insemination. These results indicate that assisted fertilization techniques may be a useful tool for achieving fertilization and embryo production in vitro in horses.

Micromanipulation

Micromanipulation technology entered the forum of human conceptionin vitroin the late 1980s. It was erroneously perceived as a new technology – a purely mechanical approach to bypass failures of conceptionin vitro, the aetiology of which were unknown. In fact, it is the modification of technology developed since the beginning of this century, and its logical utilization for conceptionin vitro, preconception (polar body) biopsy and preimplantation (blastomere and trophectoderm) biopsy in the realm of human infertility and genetic disorders.

Intracytoplasmic sperm injection — ICSI

For more than a decade in vitro fertilization (IVF) has been successful in the treatment of couples with long-standing infertility due to various aetiologies such as tubal disease, male-factor infertility, unexplained infertility and endometriosis. The usual fertilization rate in IVF for nonmale infertility cases is 60–70% of the inseminated cumulus-oocyte complexes and in andrological infertility it is only 20–30%. The lower the number of normally fertilized oocytes, the less chance there is of available embryos, so that patients may have no embryos to transfer. It has been the experience of all centres for reproductive medicine, including our own, that a certain number of couples with male-factor infertility cannot be helped by standard IVF treatment. After insemination with progressively motile spermatozoa the number of two-pronuclear oocytes was either zero or less than 5%. Furthermore, a sizeable number of couples cannot be accepted for IVF if the number of progressively motile spermatozoa in the ejaculate is below a certain threshold number such as 500 000. In the past five years, assisted fertilization procedures have been developed to circumvent the barriers that prevent sperm access to the ooplasma, namely the zona pellucida and the ooplasmic membrane. Pregnancies and births have been reported after partial zona dissection (PZD) and subzonal insemination (SUZI). The success rate of PZD and SUZI has remained moderate: the normal fertilization rate (two-pronuclear oocytes) has never exceeded 20–25% of the micromanipulated oocytes; only two-thirds of the patients have had embryo transfers of, usually, a low number of embryos, resulting in a reduced pregnancy and take-home baby rate.

Intracytoplasmic sperm injection in livestock species: an update

Intracytoplasmic sperm injection (ICSI) is a powerful technique in the field of assisted reproduction (ART) and provides exciting opportunities for studying the basic mechanisms of fertilization and early embryo development. Nevertheless, its application in agriculture and conservation biology has been greatly hampered by the low success rate reported for this method in respect of economically important species. Specifically, the rates of blastocyst formation and live newborn are greatly reduced when zygotes are generated by ICSI. Except for humans, ICSI remains a low efficiency technology in comparison with alternatives such as in vitro fertilization (IVF) and its application is less widespread. In this paper, we discuss the present status, applications and factors affecting ICSI in pigs and other species.

Microinsemination and Nuclear Transfer Using Male Germ Cells

Microinsemination has been widely used in basic reproductive research and in human-assisted reproductive technology for treating infertility. Historically, microinsemination in mammals started with research on the golden hamster; since then, it has provided invaluable information on the mechanisms of mammalian fertilization. Thanks to advances in animal genetic engineering and germ-cell technologies, microinsemination techniques are now used extensively to identify the biological significance of genes of interest or to confirm the genetic normality of gametes produced by experimental manipulations in vitro. Fortunately, in mice, high rates of embryo development to offspring can be obtained so long as postmeiotic spermatogenic cells are used as male gametes-that is, round spermatids, elongated spermatids, and spermatozoa. For some other mammalian species, using immature spermatogenic cells significantly decreases the efficiency of microinsemination. Physically unstable chromatin and low oocyte-activating capacity are the major causes of fertilization failure. The youngest male germ cells, including primordial germ cells and gonocytes, can be used in the construction of diploid embryos by nuclear-transfer cloning. The cloned embryos obtained in this way provide invaluable information on the erasure and reestablishment of genomic imprinting in germ cells.

New microinsemination techniques for laboratory animals

Since the development of a reliable mouse intracytoplasmic sperm injection (ICSI) technique in 1995, microinsemination techniques have been widely applied in several laboratory species. As gametes and embryos have specific biological and biochemical features according to the species, technical improvements are necessary for successful microinsemination that subsequently leads to normal fetal development in several species. Recent advanced reproductive research involving genetic engineering often depends on microinsemination techniques that require a high degree of skill, and new human assisted reproductive technology (ART) requires experimental models using laboratory animals. The accumulation of technical improvements in these fields should accelerate the development of microinsemination techniques in mammals, including humans.

Oocyte activation: lessons from human infertility

During fertilization, the spermatozoon penetrates through the cumulus cells and the zona pellucida that surrounds the oocyte, before it binds and fuses with the oocyte plasma membrane to induce activation. In vitro fertilization (IVF) studies performed in non-human mammals have contributed extensive knowledge regarding the mechanisms by which the spermatozoon activates the meiotic-arrested oocyte to resume meiosis, cleave and develop into an embryo. Although IVF has been used extensively for treating subfertile couples, not all of them were able to benefit from this procedure. In intracytoplasmic sperm injection (ICSI), one viable spermatozoon only is sufficient for successful fertilization of a single oocyte. Moreover, the injected fertilizing spermatozoon bypasses several physiological barriers, compared with IVF, which together could explain the high success rate for this procedure. ICSI has also allowed the identification of sperm components that are required for successful fertilization.

Recent advances in the microinsemination of laboratory animals

Microinsemination techniques were applied to laboratory animals, including mice, Mongolian gerbils, mastomys, guinea pigs and cynomolgus monkeys. After micro-insemination with spermatozoa or round spermatids, their oocytes were successfully fertilized and subsequently developed into 4-cells to blastocysts, depending on species. The efficiencies of microinsemination techniques for producing fertilized oocytes were comparable with, or superior to those of IVF in these species.

Intracytoplasmic sperm injection

Intracytoplasmic sperm injection (ICSI) can now alleviate infertility in couples who could not conceive by other means. Most patients with obstructive azoospermia and some patients with non-obstructive azoospermia can now be treated. The practice of five years of ICSI (1991-1995) is reviewed in terms of patients selection and counselling, controlled ovarian stimulation and oocyte handling, semen evaluation and preparation, ICSI procedure, oocyte damage and pronuclear status after ICSI, embryo development, embryo transfer, freezing of supernumerary embryos, obstetrical outcome, prenatal diagnosis and follow-up study of the children resulting from ICSI.

Caprine blastocyst formation following intracytoplasmic sperm injection and defined culture

Experiments were undertaken to develop intracytoplasmic sperm injection (ICSI) to produce caprine embryos out of the normal breeding season. Oocytes were obtained from 2-6 mm ovarian follicles at slaughter. Selected oocytes with two to four layers of cumulus cells were incubated in 1 ml of H-TCM199 supplemented with 10 micrograms each of oFSH and bLH (NHPP, NIDDK, NICHD, USDA) and 20% fetal bovine serum (FBS) in a thermos (38.5 degrees C) for 4.5 h during transportation. Then, oocytes were transferred into 75 microliters of freshly prepared maturation medium under paraffin oil and a mixture of 5% O2, 5% CO2 and 90% N2. Approximately 26 h after recovery oocytes were denuded by incubation with hyaluronidase (100 IU/ml) and pipetting and held at 38.5 degrees C for 90 min. Spermatozoa frozen in egg yolk extender were thawed in a 37 degrees C water bath for 15 s. Motile fractions were selected by swim-up, then incubated for 90 min in TALP with 10 micrograms heparin/ml. Each oocyte was positioned with its first polar body at 6 or 12 o'clock by a holding pipette. Sperm (1 microliter) were added to 10 microliters medium containing 10% polyvinylpyrrolidone. A sperm cell was aspirated into a pipette, and then injected head-first into the cytoplasm of an oocyte maintained in H-TCM199 + 20% FBS at 37 degrees C. Injected oocytes were transferred to HM and, after 90 min, cultured in 50 microliters of BSA-free synthetic oviduct fluid plus polyvinyl alcohol, citrate and non-essential amino acids. Results demonstrate that caprine blastocysts can be produced outside the breeding season by the use of frozen-thawed semen and injection of sperm cells with broken tails into ova followed by culture in defined medium.

Inadequate function of sterile tw5/tw32 spermatozoa overcome by intracytoplasmic sperm injection

Mice carrying two t complementary haplotypes (tw5/tw32) are totally sterile. Their spermatozoa have poor motility and fertilize neither zona-intact nor zona-free oocytes, even though they are structurally indistinguishable from control (wild-type) spermatozoa. However, when injected directly into oocytes, these infertile spermatozoa are able to participate in normal development. This suggests that infertility of tw5/tw32 male (spermatozoa) is more likely to be due to poor sperm-oocyte interaction than to genetic incompetence of sperm nuclei.

Intracytoplasmic sperm injection: achievement of high pregnancy rates in couples with severe male factor infertility is dependent primarily upon female and not male factors

OBJECTIVE

To determine the efficacy and factors affecting outcome of intracytoplasmic sperm injection (ICSI) in patients with severe male factor infertility.

DESIGN

Prospectively designed clinical trial of patients selected to participate in the study based upon the following inclusion criteria: previous total failed fertilization or unsuitable sperm parameters for conventional IVF.

SETTING

Tertiary care academic center.

PATIENTS

Ninety-two consecutive couples undergoing IVF therapy augmented with ICSI during April through December 1994 were studied.

MAIN OUTCOME MEASURES

Fertilization and ongoing implantation and pregnancy rates (PRs).

RESULTS

A total of 1,163 preovulatory oocytes were manipulated, yielding a diploid fertilization rate of 60.9%; the oocyte damage rate was 13.2%. The transfer rate was 95% with 43.1% of cycles having excess embryos that were cryopreserved. Overall, the clinical and ongoing PRs per transfer were 31.9% and 26.8%, respectively. None of the sperm parameters of the original semen analysis correlated with ICSI outcome. Female age did not affect fertilization results but had a significant impact on PR (< 34 years: 48.9%; 35 to 39 years: 22.9%; > or = 40 years: 5.9% clinical PR per transfer).

CONCLUSIONS

Intracytoplasmic sperm injection offers a new and powerful therapeutic option to treat couples with severe male factor infertility associated with a variety of sperm abnormalities. An adequate female age is a pivotal factor determining a successful outcome.

Factors of importance for the establishment of a successful program of intracytoplasmic sperm injection treatment for male infertility

OBJECTIVE

To establish an intracytoplasmic sperm injection treatment program for couples with male infertility and to determine those factors important for success.

DESIGN

A retrospective analysis of 171 consecutive cycles of intracytoplasmic sperm injection concerning 145 infertile couples.

SETTING

Infertility clinic in a private hospital associated with a university hospital.

PATIENTS

Couples with infertility in the male partner whose sperm parameters were unacceptable for conventional IVF or in whom fertilization by conventional IVF failed repeatedly.

INTERVENTIONS

One hundred seventy-one transvaginal oocyte retrievals were completed after superovulation with GnRH agonist and gonadotropins.

MAIN OUTCOME MEASURES

The parameters evaluated included fertilization, cleavage, implantation, pregnancy, and spontaneous abortion in relation to patient indications and improved procedures.

RESULTS

After intracytoplasmic sperm injection, normal fertilization occurred in 45% of the oocytes (n = 1,499). Of 171 treatment cycles, 93% of the couples had fertilization and 86% had ET. Thirty-six pregnancies were achieved. During the period studied, the mean fertilization rate increased from 21.3% during the first 17 weeks to 67.8% during the last 13 weeks, and the pregnancy rate (PR) per started cycle increased from 12.8% to 31.3%.

CONCLUSIONS

Technical factors critical for achieving high rates of fertilization and pregnancy were the use of standardized intracytoplasmic sperm injection pipettes, the immobilization of sperm before injection, and the aspiration of a minimal amount of ooplasm before reinjection with the sperm. Intracytoplasmic sperm injection appears to be superior to other micromanipulation methods for alleviating male infertility.

Intracytoplasmic sperm injection

Intracytoplasmic sperm injection (ICSI) is a promising assisted fertilization technique that may benefit women who have not become pregnant by in-vitro fertilization. ICSI and subzonal insemination (SUZI) were used to treat couples who failed fertilization after standard IVF or who could not be accepted for IVF because too few motile spermatozoa were present in the ejaculate. This paper describes the outcome of 750 consecutive cycles of SUZI and ICSI. Different aspects of these novel assisted fertilization procedures are described: patient management, ovarian stimulation, semen evaluation and treatment, oocyte collection and preparation, SUZI and ICSI techniques, assessment of fertilization and embryo cleavage, outcome of embryo transfers and the evolution of the pregnancies.

Sperm characteristics and outcome of human assisted fertilization by subzonal insemination and intracytoplasmic sperm injection

OBJECTIVE

To investigate the influence of sperm characteristics on the treatment by subzonal insemination (SUZI) and intracytoplasmic sperm injection of couples with severe male infertility.

DESIGN

A retrospective analysis of 300 consecutive cycles of assisted fertilization concerning 202 infertile couples was performed. One hundred fifty-three couples underwent 362 unsuccessful IVF cycles, whereas on 49 couples IVF was not performed because of poor sperm characteristics.

SETTING

Procedures were performed in an institutional research environment.

PATIENTS, PARTICIPANTS

Couples in which the male partner was the presumed cause of repeated failure to achieve conception by IVF or in which seminal parameters were unacceptable for IVF.

INTERVENTIONS

Three hundred transvaginal oocyte retrievals were performed after superovulation by GnRH agonist and gonadotropins.

MAIN OUTCOME MEASURES

After SUZI and intracytoplasmic sperm injection the following parameters were evaluated: fertilization, cleavage, pregnancy, and implantation rates in relation to the sperm parameters and the proportion of acrosome-free spermatozoa after different treatments.

RESULTS

Normal fertilization occurred in 18% of the oocytes treated by SUZI and in 44% after intracytoplasmic sperm injection. Only the treatment by electroporation showed a positive correlation with the fertilization rate. Fourteen pregnancies were obtained after SUZI, 8 pregnancies after intracytoplasmic sperm injection, and 8 pregnancies after a combination of the two procedures. A score calculated from the sperm parameters after selection correlated with the fertilization obtained after SUZI, whereas a score calculated from the parameters before sperm selection correlated with the pregnancy rate. Sperm morphology influenced the implantation rate of the embryos obtained with these two procedures.

CONCLUSIONS

Intracytoplasmic sperm injection and SUZI can successfully treat couples who fail IVF or who cannot benefit from IVF. Different treatments can be applied to semen samples to increase the number of acrosome-reacted spermatozoa. The few significant relations found between sperm characteristics and the outcome of assisted fertilization cannot predict the outcome.