Centromeres are chromosomal loci essential for the correct segregation of genetic material during cell division. Defects in centromere function can lead to aneuploidy and cancer. During early embryonic development in mammals, prior to the first cell division, male and female genomes are separated in pronuclei located at the centre of the zygote. Parental chromatin clusters at the interface between the two pronuclei and this clustering step is critical to avoid aneuploidy in human and bovine zygotes. Yet, despite their essential function in chromosome segregation, the position and spatial organization of centromeres during the first cell cycle in mammals is mostly unknown. Previous studies conducted in bovine embryos derived from fertilization (IVF) showed that cell cycle progression impacts on the success rate of blastocyst formation. Specifically, embryos that entered earliest into S-phase or the earliest cleaving embryos were more likely to develop into blastocysts. To determine the precise timing of these events we performed a detailed characterization of key phases of the first cell cycle in bovine zygotes derived from IVF. In parallel we examined the spatial positioning of centromeres. We identify 20 h post insemination (hpi) as the timepoint when male and female pronuclei are juxtaposed and are completing S-phase. At this timepoint, we show that centromeres are positioned distal to the pronuclear interface and use super resolution microscopy to demonstrate extensive centromere clustering into chromocentres. Our results identify distinct nuclear features observed at 20 hpi, which may serve as cell cycle markers in determining successful bovine IVF.

To compare the effect of two different assisted hatching laser protocols thinning assisted hatching laser (TAH) vs drilling of assisted hatching laser (DAH) and non-assisted hatching control group (NAC) on clinical pregnancy and live birth rates in frozen thawed cleavage stage embryo transfer cycles.

Aneuploidy in oocytes is a leading cause of implantation failure, miscarriage and congenital disorders. During meiosis, proper timing of chromosome segregation is regulated by the spindle assembly checkpoint (SAC) and the anaphase-promoting complex/cyclosome (APC/C). However, how pharmacological manipulation of these regulatory pathways affects aneuploidy remains incompletely understood. In this study, we investigated whether SAC inhibition by reversine induces aneuploidy in mouse oocytes and whether partial inhibition of APC/C by proTAME can alleviate these errors. Germinal vesicle (GV) oocytes were matured in vitro in the presence of various concentrations of reversine. To optimize the timing of treatment, oocytes were exposed to reversine for 0, 3, 5 or 7 h, followed by culture with or without proTAME. A proTAME-only group (2.5 nM) was also included. Chromosome spreads were analyzed at the metaphase II (MII) stage to determine aneuploidy rates. Reversine (5 nM) yielded an MII maturation rate of 80.5% but induced a high aneuploidy rate of 77.0%. Sequential treatment with 2.5 nM proTAME significantly reduced aneuploidy to 33.3%. In contrast, proTAME alone led to 79.0% aneuploidy, suggesting its effect is contingent upon prior SAC disruption. These results indicate that reversine compromises chromosomal integrity, while appropriately timed, low-dose proTAME can partially rescue segregation errors. Our findings underscore the potential of pharmacologically regulating APC/C activity to reduce aneuploidy and enhance oocyte quality, offering new avenues for improving outcomes in assisted reproductive technologies.

The reproductive efficiency of dairy cows decreases significantly in hot climates. Exposure to heat stress causes damage to different stages of the reproductive cycle including a decrease in the quality of oocytes. Antioxidant supplementation has been introduced as one of the main approaches to alleviate the effects of free radical damage associated with heat stress. Gamma-oryzanol (ORY), a component of rice bran oil, is introduced as a novel antioxidant. As a supplement of culture media for maturation, the effect of ORY on the development of heat-shocked bovine cumulus-oocyte complexes was evaluated in this study. At the end of maturation using the heat-shock model, a higher proportion of metaphase II oocytes (0.78 ± 0.03 vs 0.42 ± 0.03) and lower metaphase I and germinal vesicle breakdown (0.10 ± 0.02 vs 0.38 ± 0.03) were recorded for the treated group (N = 205) in comparison with the control (N = 203) ( < 0.05). Moreover, the treatment exerted upregulation of , , and transcripts in matured oocytes and GPX in CCs, along with a considerable increase in the cleavage (0.52 ± 0.04 vs 0.33 ± 0.03) and total blastocyst rates (0.30 ± 0.03 vs 0.14 ± 0.02) ( < 0.05). These results showed that ORY increased the mRNA expression of the transcripts associated with antioxidant enzymes and enhanced the developmental potential of heat-shocked bovine oocytes and warranted further studies to explore this antioxidant's influence on improving dairy cattle's reproductive efficiency during heat stress.

Circadian rhythms are intrinsic, endogenously generated cycles that regulate various physiological processes, including reproductive functions. These rhythms are orchestrated by a network of core clock genes and are influenced by external environmental cues, primarily the light-dark cycle. Disruptions in circadian rhythms can have profound effects on fertility in both males and females, impacting processes such as the estrous cycle, ovulation, sperm production, implantation and pregnancy maintenance. This review comprehensively explores the molecular mechanisms underlying circadian rhythms and their influence on reproductive health, integrating evidence from both animal models and human studies. We delve into the intricate interplay between circadian genes, hormonal regulation and environmental factors, underscoring the critical importance of circadian integrity for optimal reproductive outcomes. The potential therapeutic implications of maintaining circadian rhythms are also discussed, highlighting novel avenues for enhancing reproductive health.

This work investigated the effect of zinc oxide nanoparticles functionalized with curcumin (ZnO+CUR) supplementation during the maturation (IVM) of bovine oocytes on the embryo production and the cellular antioxidant response. A total of 1,625 cumulus-oocyte complexes (COCs) were cultured in the maturation medium in the absence (0 µM - control) or presence of different concentrations of ZnO+CUR (3 µM, 6 µM or 12 µM). After IVM, COCs were destined either to 1) embryo production or 2) analysis of reactive oxygen species production, superoxide dismutase (SOD) activity, catalase (CAT) activity and total antioxidant capacity (FRAP). The results demonstrated that the addition of 6 and 12 µM ZnO+CUR during maturation showed a higher rate of blastocyst production when compared to the control ( < 0.05). However, only 12 µM ZnO+CUR treatment showed higher rates of embryo production when compared to 3µM ZnO+CUR treatment. Supplementation of IVM medium with 6 µM ZnO+CUR reduced ROS production ( < 0.05) compared to control and 12 µM ZnO+CUR treatments. Also, the treatment containing ZnO+CUR at 12 µM had lower SOD activity after IVM than control treatment. In conclusion, the best outcome for embryo production was obtained when 6 and 12 µM ZnO+CUR was added during IVM of bovine oocytes. However, this improvement in embryo production was not associated with either the reduction of ROS production or SOD and CAT activities.

Platelet-rich plasma (PRP) and conditioned medium (CM) originating from human adipose tissue mesenchymal stem cells (ATMSCs) as two enriched sources of growth factors have a potential impact on tissue repair.

High oestradiol levels during in vitro fertilization (IVF) fresh cycles have been linked to adverse obstetric outcomes, yet whether this is due to endometrial or oocyte effects remains unclear. Investigating subsequent frozen embryo transfer (FET) cycles can help clarify the origins of these effects. This study aimed to evaluate obstetric outcomes and placental histology in FET cycles for patients with elevated serum oestradiol levels during the ovarian stimulation cycle in which the embryos were created.

The objective was to evaluate the use of resveratrol conjugated with silica nanoparticles during the maturation of bovine oocytes. The oocytes were divided into the following treatment groups during the maturation process: control ( = 159), resveratrol 0.5 μM ( = 158), resveratrol 1 μM ( = 155), nanoparticles conjugated with 0.5 μM resveratrol ( = 159), and nanoparticles conjugated with 1 μM resveratrol ( = 158). Several parameters were assessed, including cumulus oophorus size, reactive oxygen species (ROS) production, oocyte nuclear maturation, cell apoptosis, cleavage rates, and blastocyst production rates. Statistical analysis was conducted using Sigma Plot software (version 11) and SAS Studio, with statistical significance defined as ≤ 0.05 for the main effects and interactions. The results indicated that the cumulus oophorus size was smaller in the resveratrol 1 μM treatment group, and the oocyte size was reduced in the nanoparticle 1 μM treatment group. No significant differences were detected between the treatment groups in terms of ROS production, oocyte maturation, or cell apoptosis. However, the resveratrol 1 μM treatment group exhibited decreased rates of cleavage and blastocyst formation. In contrast, the nanoparticles 0.5 μM and 1.0 μM treatments showed improved cleavage and blastocyst rates compared with the resveratrol 1.0 μM treatment group. In summary, while resveratrol alone at 1 μM concentration had a negative impact on cleavage and blastocyst rates, the use of silica nanoparticles conjugated with resveratrol (both 0.5 μM and 1 μM) enhanced these outcomes, suggesting a potential advantage in using nanoparticle-conjugated resveratrol for the maturation of bovine oocytes.

This study aimed to compare the clinical outcomes of using refrigerated versus pre-warmed media for preparing time-lapse dishes in fertilization (IVF). Patients undergoing their first IVF/ICSI cycle were divided into two groups. The control group used pre-warmed culture media, while the experimental group used refrigerated culture media. The osmotic pressure of the culture droplets in both groups was tested. No statistical differences were found between the two groups' basic data. The proportion of air microbubbles affecting imaging significantly decreased (4.55% vs. 37.97%, < 0.001) when using pre-warmed media. However, the blastocyst formation rate (56.62% vs. 49.70%, = 0.046) and total high-quality embryo rate (22.26% vs. 17.06%, = 0.047) were significantly higher in the refrigerated media group compared to the pre-warmed media group. The higher rate of high-quality embryos in the refrigerated media group might result in a higher single embryo transfer rate (45.10% vs. 18.52%, = 0.020) and implantation rate (58.23% vs. 34.69%, = 0.010). From day -1 to day 1, osmolality increased, with the P-3.5 group showing a significant elevation compared to the other three groups. After 5 days of incubation, the osmotic pressure of group R-4.0 was significantly lower than that of groups P-3.5, P-4.0 and P-3.5. In conclusion, refrigerated culture media dishes helped stabilize the osmotic pressure of the culture microenvironment and reduce water evaporation. The refrigerated group showed a higher rate of high-quality embryos and live births, although pre-warmed culture media effectively reduced the occurrence of air microbubbles that affect embryo imaging in the next day's dishes.

This study aimed to investigate the efficacy of cell-free DNA (CF-DNA) in the spent cleavage and blastocyst medium versus blastomere biopsy for sex identification using short tandem repeat (STR) markers for the first time. In total, 39 samples of spent culture medium (SCM) from six couples were collected of which 28 samples were CF-DNA from blastocoel fluid + SCM (day 5) and 11 samples from SCM alone (day 3). The frequencies of allele dropout (ADO), fail rate and informativity markers were considered. The relationship between the morphology of embryos and ADO and the fail number of all markers was investigated. Sex identification rate between CF-DNA isolated from culture medium and fluorescence hybridization (FISH) was then compared with measurement of Agreement Kappa (AK). The highest frequency of informative markers belonged to DXS6801 and HPRT. There was no relationship between the ADO number of all markers and embryo morphology. A significant difference was seen between embryo morphology and fail numbers. AK value between CF-DNA isolated from culture medium and FISH was 0.516, which is moderate. The ability of CF-DNA to detect the correct diagnosis of males and females showed that all values of specificity, sensitivity, positive predictive value, and negative predictive value were 100%. The presence of embryonic CF-DNA in the SCM on day 3 as well as blastocyst medium on day 5 using STR-based multiplex PCR is approximately consistent with FISH for sex identification. Advances in DNA extraction, amplification technique, and testing may allow for preimplantation genetic testing for aneuploidy (PGT-A) and monogenic/single-gene disorders (PGT-M) as a non-invasive approach without biopsy in the future either in sex determination or chromosomal abnormality.

A blastomere containing more than one nucleus is defined as a multinucleated blastomere. In our study, we aimed to investigate the relationship between serum anti-Mullerian hormone (AMH) levels and multinucleated (MLN) embryos, one of the parameters indicating embryo quality, in intracytoplasmic sperm injection (ICSI) cycles. The results of 888 ICSI cycles of patients aged 19-45 years attending an ART (assisted reproductive technology) clinic were retrospectively analysed. Cycles with at least one MLN embryo were defined as the study group (n = 237) and cycles without MLN embryos as the control group (n = 651). Univariate and multivariate logistic regression analyses were used to determine the risk factors affecting the dependent qualitative variables. The effect of AMH levels on multinucleation was found to be a significant risk factor (p < 0.001). One unit increase in AMH levels increases the risk of the presence of MLN embryos by 1.12 times. The mean MLN embryos/total embryo ratio in the group with clinical pregnancy was 0.34 ± 0.18, while the mean MLN embryos/total embryo ratio in the group that did not achieve clinical pregnancy was 0.47 ± 0.3 (p = 0.010). The presence of an MLN embryo has been associated with poor embryo development and ART outcomes. Parameters that can predict the formation of MLN embryos before treatment are crucial for the determination of the pregnancy rate. According to our results, serum AMH levels can be used as a predictive marker for the formation of MLN embryos.

Recently, mathematical and computational approaches have been incorporated into ICSI interventions as guiding tools. However, those tools carry no prognostic potential. Improving this capability may enhance ICSI attempts and assist clinicians working in infertility clinics. This study, thus aimed to investigate whether parental parameters could have predictive potential for the quality of resulting embryos with the ICSI approach using mathematical modelling techniques. Patient data including follicle number, MI and MII oocyte numbers, sperm number, sperm morphology and motility for 765 distinct couples attending British Cyprus IVF hospital was collected. Furthermore, morphological quality data as well as aneuploidy status for the 4123 resultant embryos were obtained. Regression analyses were conducted to observe the possible correlations between parental parameters and embryo quality and ploidy. Correlation analyses showed that follicle and oocyte numbers, as well as sperm parameters can be indicative of morphological quality of resulting embryos via ICSI (p values < 0.05). On the other hand, aneuploidy prediction remains too complicated to be predicted solely by these parameters (p values > 0.05). This study indicates a predictive potential of infertility measurements for male and female partners on ICSI success and is expected to act as a basis for the development of prognostic softwares to be used in IVF clinics.

This study aimed to evaluate the effects of acetyl-L-carnitine on follicle survival and growth, stromal cell density and extracellular matrix, as well as on the expression of mRNA for nuclear factor erythroid 2-related factor (), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPX) and peroxiredoxin 6 (PRDX6) in cultured bovine ovarian cortical tissues. Ovarian fragments (3 × 3 × 1 mm) were cultured for 6 days in α-MEM alone or supplemented with 10, 50 or 100 μM acetyl-L-carnitine at 38.5°C with 5% CO in humidified air. Before (non-cultured tissues) and after culture, the ovarian fragments were fixed in 4% paraformaldehyde for 12 h for histological analysis or stored at -80ºC for mRNA expression analysis of and . The results showed that 100 μM acetyl-L-carnitine increased the percentages of morphologically normal follicles and stromal cell density in cultured ovarian tissues. On the other hand, acetyl-L-carnitine did not influence the percentage of collagen in ovarian tissue nor the expression of mRNAs for and . In conclusion, 100 μM acetyl-L-carnitine increased follicle survival and stromal cell density in cultured bovine ovarian tissues but does not influence collagen fibre distribution or the expression of mRNAs for and .

In this study, we describe the ovarian structure and oogenesis up to the final maturation of oocytes of Hypancistrus seideli. A total of sixty females were used for gonadal analysis and subsequently submitted to light and scanning electron microscopy analyses. Four maturation stages were defined: immature, maturing, mature, and spawned. The oocytes were classified into four stages (I–IV), and the presence of atretic oocytes and post-ovulatory follicles was demonstrated. During oocyte development, changes were observed in color, size, and shape, as well as in the formation of the follicular complex. These results may support reproductive management in captivity, since the species has great commercial importance in the international ornamental fish market and lacks established reproductive protocols in aquaculture. To our knowledge, this is the first morphological characterization of oogenesis in this species, providing original and detailed data that may contribute to the development of captive breeding protocols and to reducing pressure on natural stocks.

The relationship between oocyte morphology and developmental potential has been a hot research topic in assisted reproductive technology (ART). Whether inclusions in the perivitelline space (PVS) affect ART outcomes remains controversial.

Sesquizygotic twinning (SZT) is one of the rarest events that can occur in multiple pregnancies. It has only been reported twice to date. Studies indicate that sesquizygotic twins result from the splitting of a chimeric embryo at an early stage. Theories and studies suggest that SZT represents a third unique twinning mechanism that is different from dizygotic and monozygotic twinning; however, the unique features of SZT have nothing to do with the twinning mechanism. Instead, it resembles more of an atypical monozygotic twinning form according to the twinning mechanism.

Globally, numerous infertile couples have been assisted by extensive research on mammalian fertilization and the rapid development of Assisted Reproductive Technology (ART). However, 5%-15% of the couples that are selected for in vitro fertilization (IVF) experience a total fertilization failure (TFF), where no zygotes develop despite oocytes and semen parameters appear to be normal. Notably, an essential early event in fertilization is the binding of spermatozoa to the oocyte's external envelope, which followed by the spermatozoa-oocyte fusion. Meanwhile, oocyte activation is a crucial cellular process necessary to block polyspermy and start the development of the zygote. Improper membrane fusion of gametes has been demonstrated to be one of the mechanisms of TFF. Moreover, considering the large amount of research on sperm proteins in recent years, thus in this review, we characterize the role and molecular mechanisms of sperm proteins in the three key processes of gamete adhesion and fusion and oocyte activation, which would provide a comprehensive understanding of the role of sperm proteins in fertilization in mammals and a favourable reference for future studies in assisted reproduction due to FF.

In Western diets, high consumption of meat and dairy products, known to be rich in branched-chain amino acids (BCAAs), including leucine (Leu), isoleucine (Ile), and valine (Val), as well as BCAAs supplementation itself, may have unforeseen consequences on sperm quality. In addition, bodybuilders are increasingly resorting to BCAA supplementation to build-up their muscle mass. This study aimed to assess the effect of dietary BCAAs, provided alone or in combination, on semen parameters, apoptotic gene expression, and blood amino acid (AA) profiles. To address this question and determine whether these different BCAAs have a distinct impact on sperm quality and testicular homeostasis, fifty NMRI mature male mice were exposed or not to BCAAs supplementations (control diet: CTR; CTR + Leu supplementation; CTR + Ile supplementation; CTR + Val supplementation; CTR + all three BCAA supplementation). Only valine supplementation resulted in a significant decrease in sperm concentration and viability. In addition, only valine supplementation was associated with a dramatic increase in sperm immotility. The Bax/Bcl2 ratio, an indicator of apoptosis, was found to be significantly higher in the testes of BCAA-supplemented animals when compared with the other groups. expression was also significantly higher in the testes of BCAA-supplemented and Val-supplemented animals. There were no significant differences in plasma AA profiles between groups. Thus, amongst BCAAs, valine supplementation appears to carry the greatest effect on sperm functional parameters and testicular apoptotic status.