Adverse Effect of Superovulation Treatment on Maturation, Function and Ultrastructural Integrity of Murine Oocytes

Gonadotropin elevation is ootoxic to ovulatory oocytes and inhibits oocyte maturation, and activin decoy receptor ActRIIB:Fc therapeutically restores maturation

BACKGROUND

Elevated FSH often occurs in women of advanced maternal age (AMA, age ≥ 35) and in infertility patients undergoing controlled ovarian stimulation (COS). There is controversy on whether high endogenous FSH contributes to infertility and whether high exogenous FSH adversely impacts patient pregnancy rates.

METHODS

The senescence-accelerated mouse-prone-8 (SAMP8) model of female reproductive aging was employed to assess the separate impacts of age and high FSH activity on the percentages (%) of viable and mature ovulated oocytes recovered after gonadotropin treatment. Young and midlife mice were treated with the FSH analog equine chorionic gonadotropin (eCG) to model both endogenous FSH elevation and exogenous FSH elevation. Previously we showed the activin inhibitor ActRIIB:Fc increases oocyte quality by preventing chromosome and spindle misalignments. Therefore, ActRIIB:Fc treatment was performed in an effort to increase % oocyte viability and % oocyte maturation.

RESULTS

The high FSH activity of eCG is ootoxic to ovulatory oocytes, with greater decreases in % viable oocytes in midlife than young mice. High FSH activity of eCG potently inhibits oocyte maturation, decreasing the % of mature oocytes to similar degrees in young and midlife mice. ActRIIB:Fc treatment does not prevent eCG ootoxicity, but it restores most oocyte maturation impeded by eCG.

CONCLUSIONS

FSH ootoxicity to ovulatory oocytes and FSH maturation inhibition pose a paradox given the well-known pro-growth and pro-maturation activities of FSH in the earlier stages of oocyte growth. We propose the FOOT Hypothesis ("FSH OoToxicity Hypothesis), that FSH ootoxicity to ovulatory oocytes comprises a new driver of infertility and low pregnancy success rates in DOR women attempting spontaneous pregnancy and in COS/IUI patients, especially AMA women. We speculate that endogenous FSH elevation also contributes to reduced fecundity in these DOR and COS/IUI patients. Restoration of oocyte maturation by ActRIB:Fc suggests that activin suppresses oocyte maturation in vivo. This contrasts with prior studies showing activin A promotes oocyte maturation in vitro. Improved oocyte maturation with agents that decrease endogenous activin activity with high specificity may have therapeutic benefit for COS/IVF patients, COS/IUI patients, and DOR patients attempting spontaneous pregnancies.

Maternal preconception stress produces sex-specific effects at the maternal:fetal interface to impact offspring development and phenotypic outcomes†

Entering pregnancy with a history of adversity, including adverse childhood experiences and racial discrimination stress, is a predictor of negative maternal and fetal health outcomes. Little is known about the biological mechanisms by which preconception adverse experiences are stored and impact future offspring health outcomes. In our maternal preconception stress (MPS) model, female mice underwent chronic stress from postnatal days 28-70 and were mated 2 weeks post-stress. Maternal preconception stress dams blunted the pregnancy-induced shift in the circulating extracellular vesicle proteome and reduced glucose tolerance at mid-gestation, suggesting a shift in pregnancy adaptation. To investigate MPS effects at the maternal:fetal interface, we probed the mid-gestation placental, uterine, and fetal brain tissue transcriptome. Male and female placentas differentially regulated expression of genes involved in growth and metabolic signaling in response to gestation in an MPS dam. We also report novel offspring sex- and MPS-specific responses in the uterine tissue apposing these placentas. In the fetal compartment, MPS female offspring reduced expression of neurodevelopmental genes. Using a ribosome-tagging transgenic approach we detected a dramatic increase in genes involved in chromatin regulation in a PVN-enriched neuronal population in females at PN21. While MPS had an additive effect on high-fat-diet (HFD)-induced weight gain in male offspring, both MPS and HFD were necessary to induce significant weight gain in female offspring. These data highlight the preconception period as a determinant of maternal health in pregnancy and provides novel insights into mechanisms by which maternal stress history impacts offspring developmental programming.

Transcriptomic integrity of human oocytes used in ARTs: technical and intrinsic factor effects

BACKGROUND

Millions of children have been born throughout the world thanks to ARTs, the harmlessness of which has not yet been fully demonstrated. For years, efforts to evaluate the specific effects of ART have focused on the embryo; however, it is the oocyte quality that mainly dictates first and foremost the developmental potential of the future embryo. Ovarian stimulation, cryopreservation, and IVM are sometimes necessary steps to obtain a mature oocyte, but they could alter the appropriate expression of the oocyte genome. Additionally, it is likely that female infertility, environmental factors, and lifestyle have a significant influence on oocyte transcriptomic quality, which may interfere with the outcome of an ART attempt.

OBJECTIVE AND RATIONALE

The objective of this review is to identify transcriptomic changes in the human oocyte caused by interventions specific to ART but also intrinsic factors such as age, reproductive health issues, and lifestyle. We also provide recommendations for future good practices to be conducted when attempting ART.

SEARCH METHODS

An in-depth literature search was performed on PubMed to identify studies assessing the human oocyte transcriptome following ART interventions, or in the context of maternal aging, suboptimal lifestyle, or reproductive health issues.

OUTCOMES

ART success is susceptible to external factors, maternal aging, lifestyle factors (smoking, BMI), and infertility due to endometriosis or polycystic ovary syndrome. Indeed, all of these are likely to increase oxidative stress and alter mitochondrial processes in the foreground. Concerning ART techniques themselves, there is evidence that different ovarian stimulation regimens shape the oocyte transcriptome. The perturbation of processes related to the mitochondrion, oxidative phosphorylation, and metabolism is observed with IVM. Cryopreservation might dysregulate genes belonging to transcriptional regulation, ubiquitination, cell cycle, and oocyte growth pathways. For other ART laboratory factors such as temperature, oxygen tension, air pollution, and light, the evidence remains scarce. Focusing on genes involved in chromatin-based processes such as DNA methylation, heterochromatin modulation, histone modification, and chromatin remodeling complexes, but also genomic imprinting, we observed systematic dysregulation of such genes either after ART intervention or lifestyle exposure, as well as due to internal factors such as maternal aging and reproductive diseases. Alteration in the expression of such epigenetic regulators may be a common mechanism linked to adverse oocyte environments, explaining global transcriptomic modifications.

WIDER IMPLICATIONS

Many IVF factors and additional external factors have the potential to impair oocyte transcriptomic integrity, which might not be innocuous for the developing embryo. Fortunately, it is likely that such dysregulations can be minimized by adapting ART protocols or reducing adverse exposure.

Epicatechin promotes oocyte quality in mice during repeated superovulation

The negative impacts of repeated superovulation on mitochondrial function and oocyte quality remain unresolved. Epicatechin (EC), a polyphenolic compound found in the human diet with strong antioxidant activity, was investigated for its effects and underlying mechanism on embryonic development after repeated superovulation. The results showed that as the number of superovulation cycles increased, the number of 2-cell embryos decreased, the development of embryos in subsequent in vitro culture was delayed, the apoptosis rate of blastocyst cells increased and the number of blastocyst cells decreased. However, intraperitoneal injection of EC (10 mg/kg body-weight) for two consecutive days during repeated superovulation increased mitochondrial DNA copies in 2-cell embryos of mice. It also promoted the expression of antioxidant enzyme genes in ovaries, increased the content of glutathione (GSH) content and improved the antioxidant capacity of ovaries. Altogether, these results revealed that intraperitoneal injection of EC could increase the embryonic mitochondrial DNA copy number (mtDNA-CN) and enhance the ovary's antioxidant capacity and GSH content, ultimately promoting the quality of mouse embryos in the process of repeated superovulation.

Factors affecting superovulation induction in goats (Capra hericus): An analysis of various approaches

Goats are generally called a "poor man's cow" because they not only provide meat and milk but also other assistance to their owners, including skins for leather production and their waste, which can be used as compost for fertilizer. Multiple ovulation and embryo transfer (MOET) is an important process in embryo biotechnology, as it increases the contribution of superior female goats to breeding operations. The field of assisted reproductive biotechnologies has seen notable progress. However, unlike in cattle, the standard use of superovulation and other reproductive biotechnologies has not been widely implemented for goats. Multiple intrinsic and extrinsic factors can alter the superovulatory response, significantly restricting the practicability of MOET technology. The use of techniques to induce superovulation is a crucial step in embryo transfer (ET), as it accelerates the propagation of animals with superior genetics for desirable traits. Furthermore, the conventional superovulation techniques based on numerous injections are not appropriate for animals and are labor-intensive as well as expensive. Different approaches and alternatives have been applied to obtain the maximum ovarian response, including immunization against inhibin and the day-0 protocol for the synchronization of the first follicular wave. While there are several studies available in the literature on superovulation in cattle, research on simplified superovulation in goats is limited; only a few studies have been conducted on this topic. This review describes the various treatments with gonadotropin that are used for inducing superovulation in various dairy goat breeds worldwide. The outcomes of these treatments, in terms of ovulation rate and recovery of transferrable embryos, are also discussed. Furthermore, this review also covers the recovery of oocytes through repeated superovulation from the same female goat that is used for somatic cell nuclear transfer (SCNT).

Oocyte maturity, oocyte fertilization and cleavage-stage embryo morphology are better in natural compared with high-dose gonadotrophin stimulated IVF cycles

RESEARCH QUESTION

Does high-dose gonadotrophin stimulation have an effect on oocyte and early-stage embryo development?

DESIGN

This was a retrospective study including 616 natural cycle IVF (NC-IVF) and 167 conventional IVF (cIVF) cycles. In total, 2110 oocytes were retrieved and analysed in fresh cycles. In NC-IVF, only human chorionic gonadotrophin was applied to trigger ovulation. In cIVF, antagonist protocols with daily 150-300 IU of human menopausal gonadotrophins were performed. The effect of gonadotrophins on oocyte and early-stage embryo development was analysed. Primary outcomes were the occurrence of mature (metaphase II) oocytes, zygotes and embryos with good morphology at the cleavage stage 2 days after oocyte retrieval.

RESULTS

The mature oocyte rate (number of mature oocytes/number of retrieved oocytes) was higher in NC-IVF than cIVF cycles (89% versus 82%, adjusted odds ratio [aOR] 1.79, P = 0.001), as was the zygote rate per oocyte retrieved (70% versus 58%, aOR 1.76, P = 0.001) and the zygote rate per mature oocyte (79% versus 71%, aOR 1.62, P = 0.001). The percentage of zygotes that developed into cleavage-stage embryos was no different. For the transferred embryos, the probability of having a good embryo morphology with four blastomeres and a fragmentation of <10% (score 0) in cleavage-stage embryos was found to be higher in NC-IVF (proportional aOR for four blastomeres 2.00, P < 0.001; aOR 1.87 for a fragmentation score of 0, P = 0.003).

CONCLUSIONS

Oocyte maturity, oocyte fertilization and morphology of the cleavage-stage embryo are affected by high-dose gonadotrophin stimulation in fresh IVF cycles.

The effect of ovarian stimulation on aneuploidy of early aborted tissues and preimplantation blastocysts: comparison of the GnRH agonist long protocol with the GnRH antagonist protocol

PURPOSE

To compare aneuploidy rates in early aborted tissues or blastocysts between in vitro fertilization (IVF) cycles after the gonadotropin-releasing hormone (GnRH) antagonist (GnRH-ant) protocol or the GnRH agonist (GnRH-a) long protocol.

METHODS

This was a retrospective cohort study from a university-affiliated fertility center. In total, 550 early miscarriage patients who conceived through IVF/intracytoplasmic sperm injection (ICSI) after receiving the GnRH-ant or GnRH-a long protocol were analyzed to compare aneuploidy rates in early aborted tissues. To compare aneuploidy rates in blastocysts, 404 preimplantation genetic testing for aneuploidy (PGT-A) cycles with the GnRH-ant protocol or GnRH-a long protocol were also analyzed.

RESULTS

For early miscarriage patients who conceived through IVF/ICSI, compared to the GnRH-a long protocol group, the GnRH-ant protocol group had a significantly higher rate of aneuploidy in early aborted tissues (48.51% vs. 64.19%). Regarding PGT-A cycles, the rate of blastocyst aneuploidy was significantly higher in the GnRH-ant protocol group than the GnRH-a long protocol group (39.69% vs. 52.27%). After stratification and multiple linear regression, the GnRH-ant regimen remained significantly associated with an increased risk of aneuploidy in early aborted tissues and blastocysts [OR (95% CI) 1.81 (1.21, 2.71), OR (95% CI) 1.65 (1.13, 2.42)]. Furthermore, the blastocyst aneuploidy rate in the GnRH-ant protocol group was significantly higher but only in young and normal ovarian responders [OR (95% CI) 5.07 (1.99, 12.92)].

CONCLUSION

Compared to the GnRH-a long protocol, the GnRH-ant protocol is associated with a higher aneuploidy rate in early aborted tissues and blastocysts. These results should be confirmed in a multicenter, randomized controlled trial.

An Interplay between Epigenetics and Translation in Oocyte Maturation and Embryo Development: Assisted Reproduction Perspective

Germ cell quality is a key prerequisite for successful fertilization and early embryo development. The quality is determined by the fine regulation of transcriptomic and proteomic profiles, which are prone to alteration by assisted reproduction technology (ART)-introduced in vitro methods. Gaining evidence shows the ART can influence preset epigenetic modifications within cultured oocytes or early embryos and affect their developmental competency. The aim of this review is to describe ART-determined epigenetic changes related to the oogenesis, early embryogenesis, and further in utero development. We confront the latest epigenetic, related epitranscriptomic, and translational regulation findings with the processes of meiotic maturation, fertilization, and early embryogenesis that impact the developmental competency and embryo quality. Post-ART embryo transfer, in utero implantation, and development (placentation, fetal development) are influenced by environmental and lifestyle factors. The review is emphasizing their epigenetic and ART contribution to fetal development. An epigenetic parallel among mouse, porcine, and bovine animal models and human ART is drawn to illustrate possible future mechanisms of infertility management as well as increase the awareness of the underlying mechanisms governing oocyte and embryo developmental complexity under ART conditions.

Preovulatory follicle contributions to oocyte competence in cattle: importance of the ever-evolving intrafollicular environment leading up to the luteinizing hormone surge

The preovulatory intrafollicular environment plays a major role in determining oocyte competence. The basis of this review is to highlight the importance of the preovulatory follicle's physiological status prior to the preovulatory luteinizing hormone (LH) surge and onset of oocyte maturation to promote an optimal follicular microenvironment and optimal oocyte developmental competence in cattle. While the underlying mechanisms remain unclear, and are likely multifactorial, the preovulatory follicle's physiological status prior to the preovulatory LH surge is highly influential on the oocyte's capacity to undergo postfertilization embryo development. Changes in the intrafollicular environment of the preovulatory follicle including steroid hormone production, metabolome profiles, and proteome profiles likely support the oocyte's developmental and metabolic competency. This review focuses on the relationship between bovine oocyte developmental competency and antral follicle progression to the preovulatory phase, the role of the preovulatory follicle in improving oocyte developmental competence in cattle, and the importance of the ever-evolving preovulatory intrafollicular environment for optimal fertility.

The proteome, not the transcriptome, predicts that oocyte superovulation affects embryonic phenotypes in mice

Superovulation is the epitome for generating oocytes for molecular embryology in mice, and it is used to model medically assisted reproduction in humans. However, whether a superovulated oocyte is normal, is an open question. This study establishes for the first time that superovulation is associated with proteome changes that affect phenotypic traits in mice, whereas the transcriptome is far less predictive. The proteins that were differentially expressed in superovulated mouse oocytes and embryos compared to their naturally ovulated counterparts were enriched in ontology terms describing abnormal mammalian phenotypes: a thinner zona pellucida, a smaller oocyte diameter, increased frequency of cleavage arrest, and defective blastocyst formation, which could all be verified functionally. Moreover, our findings indicate that embryos with such abnormalities are negatively selected during preimplantation, and ascribe these abnormalities to incomplete ovarian maturation during the time of the conventional superovulation, since they could be corrected upon postponement of the ovulatory stimulus by 24 h. Our data place constraints on the common view that superovulated oocytes are suitable for drawing general conclusions about developmental processes, and underscore the importance of including the proteins in a modern molecular definition of oocyte quality.

Superovulation Does Not Alter Calcium Oscillations Following Fertilization

Superovulation is a common approach to maximize the number of eggs available for either clinical assisted reproductive technologies or experimental animal studies. This procedure provides supraphysiological amounts of gonadotropins to promote continued growth and maturation of ovarian follicles that otherwise would undergo atresia. There is evidence in mice, cows, sheep, and humans that superovulation has a detrimental impact on the quality of the resulting ovulated eggs or embryos. Here we tested the hypothesis that eggs derived from superovulation have a reduced capacity to support calcium oscillations, which are a critical factor in the success of embryo development. Eggs were obtained from mice that were either naturally cycling or underwent a standard superovulation protocol. The eggs were either parthenogenetically activated using strontium or fertilized in vitro while undergoing monitoring of calcium oscillatory patterns. Following parthenogenetic activation, superovulated eggs had a slightly delayed onset and longer duration of the first calcium transient, but no differences in oscillation persistence, frequency, or total calcium signal. However, in vitro fertilized superovulated eggs had no differences in any of these measures of calcium oscillatory behavior relative to spontaneously ovulated eggs. These findings indicate that although subtle differences in calcium signaling can be detected following parthenogenetic activation, superovulation does not disrupt physiological calcium signaling at fertilization, supporting the use of this method for both clinical and experimental purposes.

Defective oogenesis in mice with pristane-induced model of systemic lupus

Systemic lupus erythematosus (SLE) is a chronic systemic autoimmune disease characterized by generation of autoantibodies and severe damage of various organs. The hormonal changes associated with pregnancy and especially estrogen might lead to damage of reproductive function and ovarian quality. We employed a pristane-induced lupus model of Balb/c mice which resembles human lupus in an attempt to follow oogenesis disruption during the disease progression. The integrity of cytoskeletal and chromatin structures was estimated in oocytes derived by hormonally stimulated ovulation in lupus mice and the results were compared with those from healthy mice. Chromatin, tubulin and actin structures in oocytes were detected by Hoechst 33258, anti-alpha-tubulin antibody and rhodamine-labeled phalloidin, respectively. All available meiotic spindles were analyzed - in immature (metaphase I) and mature oocytes (metaphase II). The total number of mature oocytes obtained from lupus mice was lower compared to healthy controls. The maturation rate was 9.8 % for lupus mice, 12.7 % for 7-month old controls, and 14.3 % for the young control mice (4 weeks old). Another major difference between the studied groups was the higher percentage of defective metaphase I spindles registered in oocytes derived from lupus mice (60 % normal spindles), while for the young and older controls this proportion was 86 % and 81 %, respectively. No such difference was registered for metaphase II spindles. For both metaphase I and metaphase II oocytes, the proportions of normal actin cap and chromosomal condensation were similar between the experimental groups.

Ovulation induction is associated with altered growth but with preservation of normal metabolic function in murine offspring

OBJECTIVE

To study the effects of ovulation induction on mouse postnatal health, with a focus on growth pattern and glucose tolerance. To study the effect of ovulation induction on DNA methylation, we took advantage of the agouti viable yellow (Avy) mouse.

DESIGN

Animal study.

SETTING

University Setting.

ANIMALS

Agouti viable yellow (Avy) mice on a C57BL/6 background.

INTERVENTION(S)

Avy female mice were either allowed to mate spontaneously (control group, C) or after superovulation with 5 IU of PMSG and hCG (ovulation induction group, OI).

MAIN OUTCOME MEASURE(S)

Birth parameters and postnatal growth of the offspring were followed up to 29 weeks of age. Body composition analysis was performed by EchoMRI; fasting insulin, intraperitoneal glucose tolerance tests, and glucose-stimulated insulin secretion by beta cells were assessed to study glucose metabolism.

RESULT(S)

Mice born to superovulated dams had lower survival rates, shorter anogenital distances, and shorter crown-rump lengths. Female mice generated by OI weighed less at birth, whereas male mice generated by OI had lower weight gain and had reduced lean mass. Glucose parameters, including islet functions, did not differ between the groups. No difference in agouti coat color was noted between the groups.

CONCLUSION(S)

Ovulation induction resulted in mice having increased morphometric differences at birth and male mice showing reduced weight gain but no difference in glucose tolerance or agouti coat color.

C57BL/6J and B6129F1 Embryo Transfer: Unilateral and Bilateral Transfer, Embryo Number and Recipient Female Background Control for the Optimization of Embryo Survival and Litter Size

Simple Summary

Embryo transfer is a common procedure in rodent facilities related to rederivation protocols, recovery of cryopreserved embryos and production of genetically engineered animals. This procedure consists of the transfer of mouse embryos into the oviduct of a pseudopregnant recipient female in order to obtain live pups. The aim of this study is to further characterize the optimal conditions to perform embryo transfer using wild type strains and particularly the bilateral transfer. C57BL/6J and B6129F1 embryos were freshly collected and transferred to recipient females, after overnight culture to a 2-cell stage and tested for different conditions (unilateral and bilateral surgical procedures, variable number of embryos and reciprocity between recipient mother and embryo’s genetic background). The results achieved show that C57BL/6J transfers with a low number of embryos provide higher success rates when using unilateral transfers, but for bilateral transfers a minimum number of embryos seems to be necessary. B6129F1 presented similar results, but bilateral transfers were more effective with low number of embryos. These results allow a better planning of the embryo transfer procedure, considering low number of embryos and the choice of unilateral transfers as the ideal condition for an optimal outcome. This optimization has a positive impact on the 3R’s application: it can help to reduce the number of recipient and donor females and to improve recipient female’s welfare through the use of a less invasive technique.

Abstract

Embryo transfer (ET) is a common procedure in rodent facilities. Optimizing this technique may help to reduce the number of animals, but little information is available regarding wild type strains and the conditions that affect embryo transfer. To explore this theme, 2-cell C57BL/6J embryos were transferred after overnight culture of freshly collected zygotes using different conditions: unilateral transfers using a total of 6, 8, 12, 15, 20 and 25 embryos were performed initially; then, this strain was also used for bilateral transfers using a total of 6, 12 and 20 embryos equally divided by the two oviducts. Groups of 25 embryos were not tested for the bilateral technique, since this condition produced the lower success rate when using the unilateral technique and 20 embryos would still represent a large number of embryos. A group of 2-cell B6129F1 embryos was also transferred using unilateral and bilateral ET with 6, 12 and 20 embryos. Crl:CD1(ICR) were used as recipient females for non-reciprocal transfers and C57BL/6J were used to test reciprocal transfers (only tested for six C57BL/6J unilateral transfers). Unilateral transfers using C57BL/6J mice produced higher success rates using six embryos, compared to the other groups transferred unilaterally (p-values between 0.0001 and 0.0267), but the mean number of pups per litter was not different among groups. Bilateral transfer produced higher number of pups when 20 embryos were divided by the two oviducts compared to six (p = 0.0012) or 12 (p = 0.0148) embryos, but with no differences in success rates. No statistical differences were found between the groups of B6129F1, but better results were obtained on bilateral transfers using a total of six embryos. For the strain tested (C57BL/6J), the uterine environment (Crl:CD1(ICR) or C57BL/6J recipient) does not impact the outcome of the technique. These results complement previous work published using genetically engineered mice strains and show that unilateral transfers using low number of embryos (6), produce better outcomes when compared to bilateral or unilateral transfers using more embryos. It also highlights differences between the outcome of bilateral transfers in the two strains tested. A set of historical data of genetically engineered mice at a C57BL/6J background was also included, confirming that lower embryo numbers are related to higher success rates. Together, the outcome of these experiments can be important to reduce the number of recipient and donor females, optimize embryo transfers and improve animal welfare discouraging the use of a more invasive technique.

Is it time to reconsider how to manage oocytes affected by smooth endoplasmic reticulum aggregates?

STUDY QUESTION

Did the revised Alpha/ESHRE consensus (Vienna, 2017) bring a real answer on managing oocytes with aggregates of smooth endoplasmic reticulum (SERa)?

SUMMARY ANSWER

According to the currently available literature, a case by case approach on the time of injecting/inseminating SERa+ oocytes may be not helpful for embryologists making a decision, so we suggest fertilizing both SERa+ and SERa- oocytes and prioritizing embryos derived from SERa- oocytes.

WHAT IS KNOWN ALREADY?

In 2011, the Istanbul consensus recommended not to inject/inseminate SER+ oocytes due to adverse foetal outcomes reported in literature. At the end of 2017, a panel of experts reconsidered this recommendation and advised a case by case approach. Hence, with a lack of clear recommendations, in-vitro fertilization practitioners still have heterogeneous attitudes when managing SERa+ oocytes. In this context of controversy, an updated review could be helpful in (i) forming a common language for managing cases of SERa+ oocytes and (ii) offering the most ethical practice and best care for patients seeking infertility treatment or fertility preservation.

STUDY DESIGN, SIZE, DURATION

This review (with a last literature search on 1 June 2018) evaluated the effect of the SER dysmorphism on embryological and neonatal outcomes.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Studies were considered for inclusion if they were prospective or retrospective cohort or case-control studies. Electronic searches of the Pubmed and Embase databases were done using the keyword combination: smooth endoplasmic reticulum, SER, oocyte and zygote. Abstracts and articles written in English and limited to humans were included.

MAIN RESULTS AND THE ROLE OF CHANCE

The search returned a total of 726 studies among which 21 met the inclusion criteria. The literature does not unanimously support a negative association between SERa and embryogenesis, implantation or assisted reproductive therapy outcomes. The reviewed studies reported 112 neonatal outcomes after transfers where at least one embryo originated from oocyte affected by SERa. They included 101 healthy babies, three live births with malformations, three neonatal deaths, one stillbirth and four medical interruptions of pregnancy. After transfer of embryos exclusively derived from SERa+ oocytes, a total of 48 healthy newborns were reported along with four babies with perinatal complications (including one ventricular septal defect), one stillbirth, one neonatal death and one pregnancy termination for multiple malformations.

LIMITATIONS, REASONS FOR CAUTION

As with any review, this review was limited by the quality of the included studies especially in terms of possible methodological limitations, the limited sample size and the retrospective aspect of the studies. Among the 21 selected studies, seven were abstracts and two were case reports. Of the remaining 14 studies, only three were prospective. The tools used in identifying SERa+ oocytes may have varied from one study to another and a consequent misclassification cannot be excluded. Considering the poor resolution of light microscopy in detecting SER aggregates, we are not sure that apparently SERa- oocytes do not really exhibit such a dysmorphism if they were analysed under electronic microscopy or a time lapse system.

WIDER IMPLICATIONS OF THE FINDINGS

In the light of the existing data and the lack of a real link between fertilizing SERa+ oocytes and the occurrence of embryo aneuploidy/malformations, we think that discarding SERa+ oocytes may be not the most ethical approach even in patients with large cohorts on the day of oocyte retrieval. Avoiding the wastage of oocytes and embryos with respect to medical ethics remains a constant concern in daily IVF practice. Thus, we recommend that all mature oocytes could be fertilized and embryos originating from SERa- oocytes would be preferably transferred, even if they come from a cohort with SERa+ oocytes. The remaining embryos derived from SERa+ oocytes could be considered with a lower priority for transfer after obtaining consent from the couple if a strict follow-up of the pregnancy and the baby is performed.

STUDY FUNDING/COMPETING INTEREST(S)

We have no conflict of interest to declare and no funding was received.

REGISTRATION NUMBER

N/A.

Effects of gonadotropin administration on clinical outcomes in clomiphene citrate-based minimal stimulation cycle IVF

PURPOSE

Exogenous gonadotropins (EGn) have been used occasionally in clomiphene citrate (CC)-based minimal stimulation cycles to compensate insufficient secretion of endogenous gonadotropin; however, the effectiveness of EGn supplementation remains unknown. In the present study, we assessed whether EGn improved pregnancy outcomes in CC-based minimal stimulation cycles.

METHODS

A total of 223 patients treated with CC and EGn (CC-EGn group) were matched one to one to patients treated with CC only (CC group) by propensity score matching. Embryonic and pregnancy outcomes were retrospectively compared between the groups.

RESULTS

The numbers of retrieved oocytes, fertilized oocytes, cleaved embryos, and cryopreserved blastocysts were increased in the CC-EGn group compared with the CC group. However, the cumulative live birthrate was comparable between the two groups. Although the increased number of retrieved oocytes was correlated significantly with improvement of the cumulative live birthrate in both groups, the correlation tended to be lower in the CC-EGn group than in the CC group (odds ratio, 1.193 vs 1.553).

CONCLUSIONS

In CC-based minimal stimulation cycles, the stimulation should be started with CC only, and EGn administration should be scheduled only if insufficient secretion of endogenous gonadotropin is observed in the late follicular phase.

Effect of exogenous human chorionic gonadotropin on ovulation in mice

The implementation of assisted reproductive technologies (ART), hormonal stimulation in particular, may change the quality of ovulated oocytes. The purpose of our work was to study ovulation in CD1 mice after their stimulation with human chorionic gonadotropin (hCG) and to investigate the effects of such hormonal stimulation on the pregnancy duration, fetal losses and the weight of the offspring. No significant differences were found in the total number of ovulated oocytes or in the number of immature (without a polar body) ovulated oocytes; nor were there differences between the groups in the number of oocytes with a developing polar body. However, the number of matured oocytes with a distinct polar body was significantly higher (p < 0.05) in mice stimulated with hCG (experimental group) as compared with the controls (6.2 ± 0.86 and 2.2 ± 0.97, respectively). No significant differences were observed between the experimental and control mice in the duration of pregnancy or in the numbers of term offspring, including the percentage of live and stillborn pups. However, the body weight of the offspring in the experimental group was significantly lower (p < 0.001) as compared with the controls on the fifth day after birth (3.16 ± 0.09 and 3.76 ± 0.07, respectively). Thus, exogenous hCG facilitates the development of mouse oocytes in vivo, which leads to the larger number of their mature forms at ovulation, however, the offspring born after hCG-stimulated pregnancy was characterized by a lower body weight on the fifth day after birth.

Ovarian stimulated cycles reduce protection of follicular fluid against free radicals

Controlled ovarian hyperstimulation cycle with exogenous gonadotropins (COH) is associated with clinical complications. The aim of this work was to determine whether COH alters the physiological antioxidant status of follicular fluid in women with no reproductive dysfunction, compared to the natural cycle (NC). In this longitudinal study, forty-one women (oocyte donors) consecutively underwent NC and COH. Follicular fluid was collected at oocyte retrieval and different redox biomarkers were determined: total antioxidant activity (TAA), oxygen radical absorbance capacity (ORAC), nitric oxide, α- and γ-tocopherol, the fatty acid composition, activities of superoxide dismutase, catalase, total and Se-dependent glutathione peroxidases, and the antioxidant paraoxonase (PON) family. Results showed that TAA (1.70 ± 0.03 mM versus 1.86 ± 0.03 mM, p < 0.05), α-tocopherol (4.37 ± 0.26 μM versus 5.74 ± 0.30 μM, p < 0.05), PON1 paraoxonase (245 ± 24 nmol/min/ml versus 272 ± 27 nmol/min/ml, p < 0.05), PON1 arylesterase (87.2 ± 4.6 μmol/min/ml versus 99.3 ± 4.8 μmol/min/ml, p < 0.05), and PON3 simvastatinase (13.48 ± 0.52 nmol/min/ml versus 16.29 ± 0.72 nmol/min/ml, p < 0.001) were significantly lower in COH versus NC. Fatty acids from COH were more saturated, increasing palmitate and decreasing the n-6 and total polyunsaturated fatty acids (PUFAs). Docosahexaenoic acid also increased (p < 0.05). Results suggest that COH could lead to premature ovarian aging and provide new insights into the possible prevention of the adverse effects of ovarian hyperstimulation by directing therapeutic applications to the maintenance of the redox balance and fatty acid status, with special attention to paraoxonase proteins and docosahexaenoic acid.

Pleiotropic effects of alpha-SNAP M105I mutation on oocyte biology: ultrastructural and cellular changes that adversely affect female fertility in mice

After sperm-oocyte fusion, cortical granules (CGs) located in oocyte cortex undergo exocytosis and their content is released into the perivitelline space to avoid polyspermy. Thus, cortical granule exocytosis (CGE) is a key process for fertilization success. We have demonstrated that alpha-SNAP -and its functional partner NSF- mediate fusion of CGs with the plasma membrane in mouse oocytes. Here, we examined at cellular and ultrastructural level oocytes from hyh (hydrocephalus with hop gait) mice, which present a missense mutation in the Napa gene that results in the substitution of methionine for isoleucine at position 105 (M105I) of alpha-SNAP. Mutated alpha-SNAP was mislocalized in hyh oocytes while NSF expression increased during oocyte maturation. Staining of CGs showed that 9.8% of hyh oocytes had abnormal localization of CGs and oval shape. Functional tests showed that CGE was impaired in hyh oocytes. Interestingly, in vitro fertilization assays showed a decreased fertilization rate for hyh oocytes. Furthermore, fertilized hyh oocytes presented an increased polyspermy rate compared to wild type ones. At ultrastructural level, hyh oocytes showed small mitochondria and a striking accumulation and secretion of degradative structures. Our findings demonstrate the negative effects of alpha-SNAP M105 mutation on oocyte biology and further confirm the relevance of alpha-SNAP in female fertility.

Effect of exogenous gonadotropin on the transcriptome of human granulosa cells and follicular fluid hormone profiles

BACKGROUND

Superovulation treatment had some adverse effects on maturity and development of oocytes. Can superovulation dose of gonadotropins (Gns) affect the transcriptome of granulosa cells and follicular fluid (FF) hormone levels?

METHODS

One leading pre-ovulatory follicle per subject was used from three natural-cycle and four Gn-stimulated patients. Granulosa cells and FF samples were collected from the same leading follicle of each patient. RNA was extracted from granulosa cells and subjected to deep sequencing and analysis. Follicle-stimulating hormone (FSH), estradiol (E2), androstenedione (AND), testosterone (T), luteinizing hormone (LH), and progesterone (P4) levels in FF were measured by immunoassays. Student's t test was used for statistical analysis.

RESULTS

A total of 715 genes were up-regulated, and 287 genes were down-regulated, in the Gn-stimulated group relative to the control group. Gene Ontology analysis revealed that the down-regulated genes were enriched in cell cycle and meiosis pathways, primarily those associated with follicle or oocyte maturation and quality. On the other hand, the up-regulated genes were enriched in functions related to immunity and cytokine-cytokine receptor interactions. Compared to the follicles of natural cycle, the E2 and LH concentrations were significantly reduced (P < 0.001), the P4 concentration was significantly increased (P = 0.003), and the concentrations of FSH, T and AND had no difference in the follicles of Gn-stimulated cycle.

CONCLUSIONS

Cell cycle- and meiosis-associated genes were down-regulated by Gns stimulation, whereas immune- and cytokine-associated genes were up-regulated. Hormone levels were also affected by Gns stimulation. Compared with natural-cycle follicles,putative markers associated with oocyte quality and follicle maturation were significantly different from those in Gn-stimulated follicles. Hormone levels in follicles were compatible with the steroidogenic patterns of granulosa cell, which reflects the follicle maturation and oocyte quality.

Embryo responses to stress induced by assisted reproductive technologies

Assisted reproductive technology (ART) has led to the birth of millions of babies. In cattle, thousands of embryos are produced annually. However, since the introduction and widespread use of ART, negative effects on embryos and offspring are starting to emerge. Knowledge so far, mostly provided by animal models, indicates that suboptimal conditions during ART can affect embryo viability and quality, and may induce embryonic stress responses. These stress responses take the form of severe gene expression alterations or modifications in critical epigenetic marks established during early developmental stages that can persist after birth. Unfortunately, while developmental plasticity allows the embryo to survive these stressful conditions, such insult may lead to adult health problems and to long-term effects on offspring that could be transmitted to subsequent generations. In this review, we describe how in mice, livestock, and humans, besides affecting the development of the embryo itself, ART stressors may also have significant repercussions on offspring health and physiology. Finally, we argue the case that better control of stressors during ART will help improve embryo quality and offspring health.

Analysis of Protein Oxidative Modifications in Follicular Fluid from Fertile Women: Natural Versus Stimulated Cycles

Oxidative stress is associated with obstetric complications during ovarian hyperstimulation in women undergoing in vitro fertilization. The follicular fluid contains high levels of proteins, which are the main targets of free radicals. The aim of this work was to determine specific biomarkers of non-enzymatic oxidative modifications of proteins from follicular fluid in vivo, and the effect of ovarian stimulation with gonadotropins on these biomarkers. For this purpose, 27 fertile women underwent both a natural and a stimulated cycle. The biomarkers, glutamic semialdehyde (GSA), aminoadipic semialdehyde (AASA), N^ε-(carboxymethyl)lysine (CML), and N^ε-(carboxyethyl)lysine (CEL), were measured by gas-liquid chromatography coupled to mass spectrometry. Results showed that follicular fluid contained products of protein modifications by direct metal-catalyzed oxidation (GSA and AASA), glycoxidation (CML and CEL), and lipoxidation (CML). GSA was the most abundant biomarker (91.5%). The levels of CML amounted to 6% of the total lesions and were higher than AASA (1.3%) and CEL (1.2%). In the natural cycle, CEL was significantly lower (p < 0.05) than in the stimulated cycle, suggesting that natural cycles are more protected against protein glycoxidation. These findings are the basis for further research to elucidate the possible relevance of this follicular biomarker of advanced glycation end product in fertility programs.