Paternal Exposure to Non-essential Heavy Metal Affects Embryo Cleavage and Implantation in Intracytoplasmic Sperm Injection (ICSI) Cycles: Evidence for a Paradoxical Effect.

Although the adverse effects of non-essential heavy metals on semen quality have been demonstrated in experimental animal models and occupational human exposure studies, little is known about the reproductive efficiency of exposed sperm during the process of intracytoplasmic sperm injection (ICSI). Our study aims to evaluate the effect of paternal exposure to non-essential heavy metals on embryo efficiency outcomes (embryo cleavage, fragmentation, implantation, and live birth) in ICSI cycle. Ninety-five heterosexual couples who underwent 95 ICSI cycles and 78 fresh embryo transfers between January 2003 and December 2009 were evaluated. Men whose female partner was undergoing ICSI were asked to provide semen and blood samples. Heavy metal levels (Pb, Cd, As, Hg, Ba, and U) were analyzed using an ion-coupled plasma-mass spectrometry (ICP-MS; Agilent 7500 ce, Agilent Technologies, Germany) equipped with a cell dynamic range (CDR). Paternal exposure to trace heavy metals was found to influence intermediate reproductive endpoints in ICSI cycles. After adjusting for paternal and maternal confounders, paternal blood concentrations of Cd [-0.30(-0.11,-0.02)], As [-0.26(-0.16,-0.11)], and U [-0.22(-0.24,-0.02)] were inversely associated with embryo cell cleavage on day 3. Counterintuitively, paternal blood and semen Pb levels [0.26(0.01,0.22); 0.25(0.03,0.14)] as well as semen U levels [0.27(0.01,0.19)] were positively associated with the proportion of implanted embryos. There were no significant associations observed for clinical pregnancy and live birth rates with any paternal heavy metal concentrations in semen and blood. These findings highlight the importance of paternal health for embryo efficiency outcomes in ICSI treatment cycles and the need for more male partner inclusive counseling in fertility practice. They also underline a paradoxical positive association between some heavy metal pollutants at low exposure levels and reproductive outcomes.

Cushioned centrifugation during sperm selection increases the fertilization and cleavage rates of cattle embryos produced in vitro.

This study was conducted to evaluate the effect of utilization of an iodixanol-based solution as a cushioning method during the sperm selection utilizing discontinuous Percoll gradient centrifugation in in vitro production (IVP) of cattle embryos. In Experiment I, all aliquots of thawed semen were subjected to sperm selection using the same discontinuous Percoll® gradients, except for the following four conditions: presence of cushioning solution (Cushion Fluid, Minitube) during the first centrifugation process (C1), presence of cushioning solution during the second centrifugation process (C2), inclusion of cushioning solution in both centrifugation steps (C1-2), and no addiction of cushioning solution (C; control group). Recovery rates, sperm kinetics, and reactive oxygen species (ROS) production were evaluated. In Experiment II, sperm cells were processed using sperm selection conditions C and C1, and fertilization rates and embryonic development kinetics were compared between experimental groups. With use of condition C1, there was improvement in fertilization and cleavage rates when compared to use of condition C (56.4% compared with 45.5% and 80.0% compared 64.7%, respectively). In conclusion, results indicate the use of a cushioning solution during sperm selection positively affects the developmental potential of embryos.

Mouse embryos exposed to oxygen concentrations that mimic changes in the oviduct and uterus show improvement in blastocyst rate, blastocyst size, and accelerated cell division.

After in vivo fertilisation, the preimplantation embryo goes through cleavage during migration along the oviduct in mammals or the fallopian tube in a woman and ends up inside the uterus. This study investigates the effect of a protocol aimed at closely reproducing that natural oxygen concentration in the oviduct (7 % O2 from day 1 to day 3 and 2 % from day 3 to day 5), in contrast to the concentrations (5 % or 20 %) widely used in practice in ART using morphokinetic. Female mice (BI6/CBAca) were sacrificed, and zygotes were isolated 20 h after mating and randomly allocated to three parallel groups, which were grown under high atmospheric, low, or sequential oxygen concentrations. Zygotes were cultured in GTL medium (Vitrolife) and observed by the Primovision time-lapse system. Blastocyst rate at 120 h in the sequential group (91.3 %) was significantly increased over the high (76.3 %) and low (74.4 %) groups. Blastocyst size was also enlarged in the sequential group compared to the high and low groups. Moreover, cell division in the sequential group was significantly faster at almost every cleavage stage than it was in the other groups. Notably, the duration of the interims between stages also differed significantly between the groups. This study demonstrated that, in comparison to routinely used high or low oxygen conditions, oxygen concentrations mimicking changes in the oviduct and uterus significantly improve the blastocyst rate and size and accelerate cell division at several stages as well as the interims between cleavage events.

Analysis of endometrial thickness threshold and optimal thickness interval in cleavage embryo hormone replacement freeze-thawed embryo transfer (HRT-FET).

To investigate the effect of endometrial thickness on the clinical outcome of cleavage embryo HRT-FET on the day of embryo transfer and analyzed the threshold and optimal thickness interval corresponding to ideal clinical pregnancy rate by statistical method. A total of 5861 HRT-FET cycles with cleavage embryo transferred from January 2013 to December 2017 in the Reproductive Medicine Center of Henan Provincial People's Hospital were studied retrospectively．Fifth-order grouping of endometrial thickness (EMT) on embryo transfer day as a continuous variable by statistical software, they were divided into five subgroups: Q1 (EMT:4.0-7.9 mm), Q2 (EMT: 8.0-8.9 mm), Q3 (EMT: 9.0-9.5 mm), Q4 (EMT: 9. 6-10.9 mm), Q5 (EMT: 11.0-19.0 mm). After adjusting for confounding factors, the clinical pregnancy rate and live birth rate in other groups were higher than Group Q1 significantly (p < .05). The cutoff value of the endometrial thickness was 8.6 mm, When endometrial thickness was less than 8.6 mm, with each additional 1 mm of endometrial thickness, clinical pregnancy rate increased by 49% (OR = 1.49, 95%CI (1.35, 1.66), p < .001), the live birth rate increased by 59% (OR= 1.59, 95%CI (1.42, 1.78), p < .001), When the endometrial thickness was thicker than the threshold, clinical pregnancy rate (OR = 1.02, 95%CI (0.97, 1.07), p = .398) and the live birth rate (OR = 1.00, 95%CI (0.96, 1.05), p = .398) remained stable. In the cleavage embryo HRT-FET cycle, endometrial thickness is a curvilinear relationship with clinical outcome, the optimal endometrial thickness interval for ideal clinical outcome was 8.6-15mm.

Timing of the First Cleavage and In Vitro Developmental Potential of Bovine Somatic Cell Nuclear Transfer Embryos Activated by Different Protocols.

The objective of this study was to examine the relationship between the timing of the first cleavage and in vitro development of somatic cell nuclear transfer (SCNT) embryos produced by different activation protocols. SCNT embryos were activated with calcium ionophore A23187 and further treated with 6-dimethylaminopurine (DMAP group), cycloheximide (CHX group), or anisomycin (ANI group). The proportion of SCNT embryos that cleaved within 18 hours after activation was significantly higher in the DMAP group (20%) than that in the CHX and ANI groups (3% and 2%, respectively). More than 70% of the cleaved embryos were observed within 24 hours in the DMAP and CHX groups, and within 26 hours in the ANI group. The blastocyst formation rate of SCNT embryos decreased gradually as the time from activation to the first cleavage increased in the DMAP group. The blastocyst formation rate of SCNT embryos cleaved at 22 hours (>20 to ≤22 hours) in the CHX group or within 26 hours in the ANI group was significantly higher than that of SCNT embryos cleaved more than 26 hours in each group. These results indicate that the activation protocol affects the timing of the first cleavage and subsequent in vitro development potential of bovine SCNT embryos and that late-cleaving embryos have a low developmental potential irrespective of the activation protocol.

Equine blastocyst production under different incubation temperatures and different CO2 concentrations during early cleavage.

Some basic parameters for equine invitro embryo production have not yet been established, including the optimum temperature for maturation and embryo culture, and the optimum CO2 concentration and pH during early embryo development. To explore this, we first performed cultures in incubators set at 37.2°C, 37.7°C or 38.2°C. At these temperatures, the corresponding maturation rates were 33%, 38% and 42%; cleavage rates were 84%, 86% and 88%; and blastocyst rates were 35%, 44% and 44% per injected oocyte. These rates did not differ significantly (P>0.2). We then evaluated three different CO2 concentrations (6%, 6.5% or 7% CO2) in 5% O2 for culture over Days 0-5 after intracytoplasmic sperm injection, using a commercial human embryo medium with added serum, at 38.2°C. The pH values of these media were 7.36, 7.33 and 7.29 respectively. In the presence of 6%, 6.5% or 7% CO2, cleavage rates were 68%, 80% and 70% respectively, and blastocyst rates per injected oocyte were 42%, 54% and 27% respectively. The blastocyst rate for the 7% CO2 treatment was significantly lower than that for the 6.5% CO2 treatment (P<0.05). We conclude that equine invitro embryo production is equally effective within the range of 37.2-38.2°C, but that equine early cleavage stage development is sensitive to small changes in CO2 atmosphere and/or medium pH.

Early embryonic development of bovine oocytes challenged with LPS in vitro or in vivo.

The aim of this study was to evaluate the effect of exposing bovine oocytes to lipopolysaccharides (LPS) in vivo and in vitro on early embryo development. In experiment 1, cumulus oocyte complexes (COCs, n = 700/group) were challenged with 0, 0.1, 1.0 or 5.0 µg/mL of LPS during in vitro maturation (IVM). Later, in vitro fertilization (IVF) and in vitro culture (IVC) were performed. In experiment 2, COCs (n = 200/group) matured and in vitro fertilized without LPS were subjected to IVC with the same doses of LPS from experiment 1. In experiment 3, heifers received two injections of saline solution (n = 8) or 0.5 µg/kg of LPS (n = 8) 24 h apart, and 3 days later, COCs were recovered and submitted to IVM, IVF, and IVC. In experiments 1 and 3, the expression of TLR4, TNF, AREG and EREG genes in cumulus cells was evaluated. Exposure to 1 and 5 µg/mL of LPS during IVM decreased nuclear maturation (39.4 and 39.6%, respectively) compared with control (63.6%, P < 0.05). Despite that, no effect on cleavage and blastocyst rates were observed. Exposure to LPS during IVC did not affect embryonic development. In vivo exposure to LPS decreased the in vitro cleavage rate (54.3 vs 70.2%, P = 0.032), but cleaved embryos developed normally. Number of cells per embryo and gene expression were not affected by the LPS challenge in any experiment. In conclusion, although in vitro exposure to LPS did not affect early embryo development, in vivo LPS exposure reduced cleavage rate.

Follicle-stimulating hormone administration affects amino acid metabolism in mammalian oocytes†.

Culture media used in assisted reproduction are commonly supplemented with gonadotropin hormones to support the nuclear and cytoplasmic maturation of in vitro matured oocytes. However, the effect of gonadotropins on protein synthesis in oocytes is yet to be fully understood. As published data have previously documented a positive in vitro effect of follicle-stimulating hormone (FSH) on cytoplasmic maturation, we exposed mouse denuded oocytes to FSH in order to evaluate the changes in global protein synthesis. We found that dose-dependent administration of FSH resulted in a decrease of methionine incorporation into de novo synthesized proteins in denuded mouse oocytes and oocytes cultured in cumulus-oocyte complexes. Similarly, FSH influenced methionine incorporation in additional mammalian species including human. Furthermore, we showed the expression of FSH-receptor protein in oocytes. We found that major translational regulators were not affected by FSH treatment; however, the amino acid uptake became impaired. We propose that the effect of FSH treatment on amino acid uptake is influenced by FSH receptor with the effect on oocyte metabolism and physiology.

Crocin supplementation during oocyte maturation enhances antioxidant defence and subsequent cleavage rate.

The purpose of the present study was to assess the effect of crocin supplementation during oocyte maturation on the antioxidant defence and anti-apoptotic ability and subsequent developmental competence of porcine oocytes. Oocytes were cultured in media containing 0, 300, 400 or 500 µg/ml of crocin. Upon maturation, the maturation rates, reactive oxygen species (ROS) and glutathione (GSH) levels, mRNA expression of genes (SOD, CAT, GPx, Bcl-2, BAX and Caspase3), expression of cleaved caspase3 and subsequent embryo cleavage rates were measured. Results indicated that the maturation rate of the 400 µg/ml group was 86.80% (p < 0.01). The ROS concentration of the 500 µg/ml group was the lowest (p < 0.01). The GSH concentration of the 400 µg/ml group was the highest (p < 0.01). The SOD, CAT and GPx mRNA expression levels were the highest in the 300, 400 and 500 µg/ml groups, respectively, with the expression levels of all genes being significantly higher than that of the control group (p < 0.01). The Bcl-2/BAX mRNA expression ratio in 400 and 500 µg/ml groups significantly higher than other groups and significantly decreased caspase3 expression level (p < 0.01). The expression level of cleaved caspase3 in the 500 µg/ml treatment group was the lowest, significantly lower than that of the control group (p < 0.01). The cleavage rate of the 400 µg/ml group was 62.50% (p < 0.01). These experimental results show that the supplementation of in vitro culture medium with 400 µg/ml of crocin significantly enhanced the antioxidant defence and anti-apoptotic ability and subsequent cleavage rate of porcine embryo.

Exogenous glutathione improves intracellular glutathione synthesis via the γ-glutamyl cycle in bovine zygotes and cleavage embryos.

Excess reactive oxygen species (ROS) generated in embryos during in vitro culture damage cellular macromolecules and embryo development. Glutathione (GSH) scavenges ROS and optimizes the culture system. However, how exogenous GSH influences intracellular GSH and improves the embryo developmental rate is poorly understood. In this study, GSH or GSX (a stable GSH isotope) was added to the culture media of bovine in vitro fertilization embryos for 7 days. The cleavage rate, blastocyst rate, and total cell number of blastocysts were calculated. Similarly to GSH, GSX increased the in vitro development rate and embryo quality. We measured intracellular ROS, GSX, and GSH for 0-32-hr postinsemination (hpi) in embryos (including zygotes at G1, S, and G2 phases and cleaved embryos) cultured in medium containing GSX. Intracellular ROS significantly decreased with increasing intracellular GSH in S-stage zygotes (18 hpi) and cleaved embryos (32 hpi). γ-Glutamyltranspeptidase ( GGT) and glutathione synthetase ( GSS) messenger RNA expression increased in zygotes (18 hpi) and cleaved embryos treated with GSH, consistent with the tendency of overall GSH content. GGT activity increased significantly in 18 hpi zygotes. GGT and GCL enzyme inhibition with acivicin and buthionine sulfoximine, respectively, decreased cleavage rate, blastocyst rate, total cell number, and GSH and GSX content. All results indicated that exogenous GSH affects intracellular GSH levels through the γ-glutamyl cycle and improves early embryo development, enhancing our understanding of the redox regulation effects and transport of GSH during embryo culture in vitro.

Detection of CD9 and CD81 tetraspanins in bovine and porcine oocytes and embryos.

Tetraspanins are multifunctional molecules located in specific microdomains on the plasma membrane. Thanks to their ability to form networks with other proteins they can participate in many cellular functions. Tetraspanins are part of the interactive network in gametes; however, their precise role in fertilization is not yet clear. The aim of this study was to compare the localization of CD9 and CD81 tetraspanins during oocyte maturation and early development of the embryos in bovine and porcine model. CD9 was detected on the oocyte plasma membrane and vesicles in the perivitelline space of bovine oocytes and embryos. We suggest that CD9 could be a component involved in transzonal projections. Based on the results of in vitro fertilization assay, CD9 and CD81 seem to be part of a more complex fusion network on the plasma membrane of bovine oocytes. On the other hand, both tetraspanins showed a clustered expression pattern on the plasma membrane and inner margin of zona pellucida (ZP) in porcine oocytes and embryos. We found a new species-specific pattern of CD9 and CD81 distribution in ZP which could reflect their specialized role in processes associated with cell adhesion and intercellular communication upon fertilization.

Exposure to elevated glucose concentrations alters the metabolomic profile of bovine blastocysts.

Chronically high blood glucose concentrations are a characteristic of diabetes mellitus. Maternal diabetes affects the metabolism of early embryos and can cause a delay in development. To mimic maternal diabetes, bovine in vitro fertilization and embryo culture were performed in fertilization medium and culture medium containing 0.5, 2, 3, and 5 mM, glucose whereas under control conditions, the medium was glucose free (0 mM). Compared to control conditions (0 mM, 31%), blastocyst development was decreased to 23% with 0.5 and 2 mM glucose. Presence of 3 or 5 mM glucose in the medium resulted in decreased blastocyst rates (20% and 10% respectively). The metabolomic profile of resulting day 8 blastocysts was analysed by UPLC-MS/MS, and compared to that of blastocysts cultured in control conditions. Elevated glucose concentrations stimulated an increase in glycolysis and activity of the hexosamine pathway, which is involved in protein glycosylation. However, components of the tricarboxylic acid cycle, such as citrate and alpha-ketoglutarate, were reduced in glucose stimulated blastocysts, suggesting that energy production from pyruvate was inefficient. On the other hand, activity of the polyol pathway, an alternative route to energy generation, was increased. In short, cattle embryos exposed to elevated glucose concentrations during early development showed changes in their metabolomic profile consistent with the expectations of exposure to diabetic conditions.

Hormonal stimulation in 4 to 7 months old Nelore (Bos taurus indicus) females improved ovarian follicular responses but not the in vitro embryo production.

The inclusion of pre-pubertal bovine females in reproductive management could allow in vitro embryo production and reduce generation interval, thereby causing faster genetic gain of the herd. However, oocytes of pre-pubertal females have lower competence, blastocyst production, and pregnancy rates than those collected from pubertal animals. This study aimed to evaluate the effect of an induced hormonal stimulation on the serum concentrations of Anti-Mullerian hormone (AMH) and FSH, ovarian responses, ovum pick up (OPU), and in vitro produced embryos (IVP) from oocytes obtained from four-to seven-months old Nelore female cattle. In a crossover design, these females were randomly allocated into: 1) Treated Group (TG, n = 9): the animals were subjected to a hormonal protocol (implanted progesterone device, estradiol benzoate, LH, and FSH) from Day 0 (the start of the treatment) to Day 7 (OPU day), and 2) Control Group (CG, n = 9): the females did not receive any hormonal stimulation, but they had ablation of their largest follicles on Day 2 of experiment. Blood collection for serum FSH measurements was done on Days 5, 6, 7, and 8, and collection for serum AMH measurements was done on Days 5 and 8. As hypothesized, TG had higher serum FSH concentrations (p < 0.05) on Day 5 (1.16 ±â€¯0.31 ng/mL), Day 6 (1.21 ±â€¯0.45 ng/mL), and Day 7 (0.95 ±â€¯0.26 ng/mL) than CG (0.56 ±â€¯0.17 ng/mL on Day 5, 0.60 ±â€¯0.25 ng/mL on Day 6, and 0.60 ±â€¯0.14 ng/mL on Day 7). However, serum AMH concentrations were neither significantly different (p > 0.05) between CG and TG, nor between the collection days. Hormonal stimulation also increased (p < 0.05) total follicular population (20.0 ±â€¯4.95 CG vs 26.66 ±â€¯4.24 TG), ovarian diameter (13.08 ±â€¯1.0 mm CG vs 14.81 ±â€¯1.38 mm TG) and number of follicles ≥2.5 mm (6.88 ±â€¯2.14 CG vs 11.55 ±â€¯4.09 TG). In TG, grades I and II oocytes predominated, whereas, in CG grades III and IV oocytes were more abundant (p < 0.05). No significant increases (p > 0.05) in the cleavage (49.33% CG vs 51.42% TG), cleavage > 4 cells (9.33% CG vs 16.19% TG), and blastocysts rates (1.33% CG vs 8.57% TG) were seen in TG. This hormonal protocol increased serum FSH concentrations that possibly contributed to increases in the observed follicle, as well as improving oocyte quality. This exogenous hormonal stimulation increased available oocytes numbers for IVP, despite no increase in the in vitro embryo production efficiency.

Randomized controlled trial of low (5%) versus ultralow (2%) oxygen for extended culture using bipronucleate and tripronucleate human preimplantation embryos.

OBJECTIVE: To determine whether [1] exposure of embryos to 5% oxygen (O2) from day 1 (D1) to D3, and then to 2% O2 from D3 to D5, improves total blastocyst yield, as compared with continuous exposure to 5% O2; and [2] extended culture in 2% O2 alters key metabolic processes and O2-regulated gene expression in human preimplantation embryos. DESIGN: Randomized controlled trial. SETTING: Academic medical center. PATIENT(S): Bipronucleate and tripronucleate embryos donated for research. INTERVENTION(S): On D1, sibling zygotes were randomized to culture in 5% O2 from D1 to D5 (n = 102; "5% group") or 5% O2 from D1 to D3, then 2% O2 from D3 to D5 (n = 101, "2% group"). MAIN OUTCOME MEASURE(S): Developmental stage and grade; D5 total cell counts; mass spectrometry of spent media; quantitative polymerase chain reaction of 21 genes in inner cell mass and trophectoderm. RESULT(S): Among cleaved embryos (n = 176, 87%), those in the 2% group were less likely to arrest at the cleavage stage on D5 (34 of 87, 39.1%) compared with the 5% group (52 of 89, 58.4%) (adjusted odds ratio 0.38, 95% confidence interval 0.18-0.80). Those in the 2% group were more likely to blastulate (35 of 87, 40.2%) than those in the 5% group (20 of 89, 22.5%) (adjusted odds ratio 2.55, 95% confidence interval 1.27-5.12). Culture in 2% O2 was associated with significantly fewer cells in early and advanced blastocysts, alteration in relative abundances of anabolic amino acids and metabolites involved in redox homeostasis, and differential expression of MUC1 in trophectoderm. CONCLUSION(S): These findings provide foundational evidence for future investigation of 2% O2 as the preferred O2 tension for extended culture of human embryos.

Embryo development until blastocyst stage with and without renewal of single medium on day 3.

OBJECTIVE: This study aimed to assess the effects of using a single culture medium not renewed on day 3 on the development of the embryo up to the blastocyst stage. METHODS: The study was carried out in the Assisted Reproduction Laboratory of Clínica Miraflores in the period ranging from April to December of 2016. The study included 589 human embryos obtained from 82 couples submitted to IVF/ICSI with donor oocytes. The couples were randomly divided into two groups: group 1 (medium renewed on day 3) and group 2 (medium not renewed on day 3). RESULTS: Significant differences in pregnancy rates, implantation rates, and blastocyst formation were not observed. CONCLUSION: No statistically significant difference was found between the groups with respect to the analyzed parameters. However, a non-significant trend was observed in favor of the group without medium renewal for clinical pregnancy and positive pregnancy rates (ß-hCG).

Calcium-sensing receptor (CASR) is involved in porcine in vitro fertilisation and early embryo development.

It has been demonstrated that extracellular calcium is necessary in fertilisation and embryo development but the mechanism is still not well understood. The present study mainly focussed on the extracellular calcium effector called the calcium-sensing receptor (CASR) and examined its expression in porcine gametes and embryos and its function during fertilisation and early embryo development. By using reverse transcription polymerase chain reaction, CASR was found to be expressed in porcine oocytes, spermatozoa and embryos at different developmental stages. Functionally, medium supplementation with a CASR agonist or an antagonist during in vitro fertilisation (IVF) and in vitro culture (IVC) was tested. During fertilisation, the presence of a CASR agonist increased sperm penetration rate and decreased polyspermy rate leading to an increased normal fertilisation rate. During embryo development, for the IVF embryos, agonist treatment during IVC significantly increased cleavage rate and blastocyst formation rate compared with the control group. Furthermore, parthenogenetically activated embryos showed similar results with lower cleavage and blastocyst formation rates in the antagonist group than in the other groups. It was concluded that CASR, as the effector of extracellular calcium, modulates porcine fertilisation and early embryo development.

Impact of 3.5% O2 culture on embryo development and clinical outcomes: a comparative study.

OBJECTIVE: To evaluate the effect of culturing human embryos in vitro in 3.5% oxygen (O2) concentration. DESIGN: Comparative study. SETTING: Private IVF center. PATIENT(S): The study included 558 women in two groups. INTERVENTION(S): After intracytoplasmic sperm injection (ICSI), women's oocytes were assigned to undergo cultivation in either 3.5% O2 concentration (intervention) or 5% O2 level (control group), continuously, from day 0 through day 5 or 6. MAIN OUTCOME MEASURE(S): Clinical pregnancy rate (PR) after ET. RESULT(S): There were significantly higher fertilization and cleavage rates in the 3.5% O2 group (odds ratio [OR] 1.72, 95% confidence interval [CI] 1.53-1.93) and (OR 3.74, 95% CI 2.30-6.07) than in the 5% O2 group. The compaction rate on day 3, and the number of formed, high-quality and cryopreserved blastocysts on day 5 were significantly lower in 3.5% O2 than in 5% O2 concentration ([OR 0.81, 95% CI 0.69-0.91], [OR 0.40, 95% CI 0.36-0.46], [OR 0.32, 95% CI 0.28-0.37] and [OR 0.47, 95% CI 0.40-0.54]), respectively. Culturing embryos in 3.5% O2 concentration led to significantly lower rates of biochemical pregnancy, clinical PR, and implantation ([OR 0.66, 95% CI 0.47-0.92], [OR 0.60, 95% CI 0.43-0.84] and [OR 0.61, 95% CI 0.46-0.81]), respectively. CONCLUSION(S): Culturing human embryos, continuously from day 0 to 5 or 6, in 3.5% O2 concentration is associated with significantly lower blastocyst formation rate and clinical outcomes parameters, but rather with significantly higher rates of fertilization and cleavage. Whether these findings hold true for other patient populations and culture media brands remain unknown.

The beneficial effect of repaglinide on in vitro maturation and development ability of immature mouse oocytes.

Repaglinide is a hypoglycemic drug, causing depolarization of the cell membrane, opening the voltage-gated calcium channels, and then increasing intracellular calcium in the pancreatic B cells by inhibition of the K-ATP-sensitive channels. Oocyte in vitro maturation (IVM) is influenced by different factors such as calcium signaling. In this study, we examined the effects of repaglinide on in vitro maturation and fertilization ability of mouse oocyte. Immature oocytes were isolated from female Naval Medical Research Institute mice which are 6-8 wk old mechanically and then cultured in 30 µl droplets of T6 medium with different concentrations of repaglinide. The control group did not receive repaglinide (R0). Treatment groups received different concentrations (5, 10, and 100 nM and 1 and 10 µM) of repaglinide (R1, R2, R3, R4, and R5, respectively). Oocyte in vitro maturation rate was assessed after 24 h. In vitro fertilization was performed using metaphase II oocytes obtained from R0 and R4 treatments. Embryo cleavage rate was calculated at 48 h post-IVF. Chi-square test was used for evaluating difference between control and treatment groups (p < 0.05). Oocyte maturation rate after 24 h in treatment groups R2, R3, R4, and R5 was significantly higher than that in the control (p < 0.05). Supplementation of medium with 1 µM of repaglinide (R4) during IVM significantly improved outcome of embryo cleavage rate than control at 48 h post-IVF (p < 0.05). In conclusion, repaglinide can be considered as an effective agent for in vitro oocyte maturation and embryo cleavage.

The developmental effects of pentachlorophenol on zebrafish embryos during segmentation: A systematic view.

Pentachlorophenol (PCP) is a typical toxicant and prevailing pollutant whose toxicity has been broadly investigated. However, previous studies did not specifically investigate the underlying mechanisms of its developmental toxicity. Here, we chose zebrafish embryos as the model, exposed them to 2 different concentrations of PCP, and sequenced their entire transcriptomes at 10 and 24 hours post-fertilization (hpf). The sequencing analysis revealed that high concentrations of PCP elicited systematic responses at both time points. By combining the enrichment terms with single genes, the results were further analyzed using three categories: metabolism, transporters, and organogenesis. Hyperactive glycolysis was the most outstanding feature of the transcriptome at 10 hpf. The entire system seemed to be hypoxic, although hypoxia-inducible factor-1α (HIF1α) may have been suppressed by the upregulation of prolyl hydroxylase domain enzymes (PHDs). At 24 hpf, PCP primarily affected somitogenesis and lens formation probably resulting from the disruption of embryonic body plan at earlier stages. The proposed underlying toxicological mechanism of PCP was based on the crosstalk between each clue. Our study attempted to describe the developmental toxicity of environmental pollutants from a systematic view. Meanwhile, some features of gene expression profiling could serve as markers of human health or ecological risk.

The effects of permeating cryoprotectants on intracellular free-calcium concentrations and developmental potential of in vitro-matured feline oocytes.

Embryos produced from vitrified feline oocytes have resulted in pregnancies, but the efficiency of oocyte vitrification in cats is still low. Our objectives were to evaluate the effects of exposing feline oocytes to ethylene glycol (EG), propanediol (PrOH) and dimethyl sulfoxide (DMSO) on changes in intracellular free-calcium concentrations ([Ca(2+)]i), the time needed for enzymatic digestion of the zona pellucida (ZP), the incidence of parthenogenetic activation and degeneration and embryonic development following in vitro fertilisation (IVF). All of the chemicals tested altered [Ca(2+)]i, but changes in [Ca(2+)]i, resistance of the ZP to enzymatic digestion and the incidence of parthenogenetic activation (<5% for all treatments) were not affected (P>0.05) by extracellular Ca(2+). Exposure to EG (>44.1%) and DMSO (19.7%) increased (P<0.05) oocyte degeneration compared with control oocytes and oocytes exposed to PrOH (≤2.5%). Following exposure to a combination of PrOH and DMSO (10% v/v each), blastocyst development (per cleaved embryo; 52.1%) was similar (P>0.05) to control oocytes (64.4%). When oocytes were vitrified with PrOH and DMSO, 28.3% of surviving (intact plasma membrane) oocytes cleaved following IVF, but no blastocyst developed. When a non-permeating cryoprotectant (galactose, 0.25M) was added to the vitrification medium, 47.7% of surviving oocytes cleaved and 14.3% developed to the blastocyst stage.