The effect of early irregular cell division of human embryos on blastocyst euploidy: considerations from the subsequent development of the blastomeres by direct or reverse cleavage.

OBJECTIVE: To investigate whether blastocysts that divide irregularly reduce subsequent blastocyst euploidy. DESIGN: Retrospective study. SETTING: Private clinic. PATIENT(S): A total of 122 blastocysts for which consent for disposal and research use was obtained. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Results of next-generation sequencing analysis of the blastocysts and whether blastomeres by normal or irregular divisions subsequently participated in blastocyst formation or not. RESULT(S): The embryos were classified according to their dynamics until the second cleavage. The blastocyst euploidy rates were 33.3% (19/57) in the normal cleavage (NC) group, 38.3% (18/47) in the direct cleavage (embryos with one cell dividing into 3 cells) (DC) group, and 72.2% (13/18) in the reverse cleavage (RC) (embryos with fused cells once divided) group. The rate of the RC group was significantly higher than that of the NC group. The blastocyst participation rate of the blastomeres were 95.6% in the NC group and 56.5% in that derived from DC of the first cleavage, and 91.7% in that of blastomeres derived from normal division of the second cleavage and 53.6% in that derived from DC of the second cleavage, both of which were significantly lower in the latter. In the RC group, the rates of fused and nonfused blastomeres were 62.1% and 87.5%, respectively, with no significant difference. CONCLUSION(S): The blastomeres generated by DC were often excluded from blastocyst formation, and we speculate that this is one reason why their division does not reduce blastocyst euploidy. The association between RC and euploidy of blastocysts merits further study.

Evaluation of artificial intelligence using time-lapse images of IVF embryos to predict live birth.

RESEARCH QUESTION: Can artificial intelligence (AI) improve the prediction of live births based on embryo images? DESIGN: The AI system was created by using the Attention Branch Network associated with deep learning to predict the probability of live birth from 141,444 images recorded by time-lapse imaging of 470 transferred embryos, of which 91 resulted in live birth and 379 resulted in non-live birth that included implantation failure, biochemical pregnancy and clinical miscarriage. The possibility that the calculated confidence scores of each embryo and the focused areas visualized in each embryo image can help predict subsequent live birth was examined. RESULTS: The AI system for the first time successfully visualized embryo features in focused areas that had potential to distinguish between live and non-live births. No visual feature of embryos were visualized that were associated with live or non-live births, although there were many images in which high-focused areas existed around the zona pellucida. When a cut-off level for the confidence score was set at 0.341, the live birth rate was significantly greater for embryos with a score higher than the cut-off level than for those with a score lower than the cut-off level (P < 0.001). In addition, the live birth rate of embryos with good morphological quality and confidence scores higher than 0.341 was 41.1%. CONCLUSIONS: The authors have created an AI system with a confidence score that is useful for non-invasive selection of embryos that could result in live birth. Further study is necessary to improve selection accuracy.

CD9 gene variations are not associated with female infertility in humans.

BACKGROUND/AIMS: To determine whether genetic alterations in the CD9 gene are associated with female infertility in humans. METHODS: We sequenced the entire coding region of this gene in 86 Japanese women with unexplained infertility and further conducted a case-control study of six tagging single nucleotide polymorphisms (SNPs) in this gene using an additional 164 samples obtained from a fertile control group. RESULTS: No disease-causing mutation in the CD9 gene was evident in these samples and no significant association between the tagging SNPs and the studied cohort was identified. CONCLUSIONS: Our findings do not support the hypothesis that genetic alterations of the CD9 gene cause female infertility in humans.

Metabolism of exogenous fatty acids, fatty acid-mediated cholesterol efflux, PKA and PKC pathways in boar sperm acrosome reaction.

PURPOSE: For understanding the roles of fatty acids on the induction of acrosome reaction which occurs under association of cholesterol efflux and PKA or PKC pathways in boar spermatozoa, metabolic fate of alone and combined radiolabeled 14C-oleic acid and 3H-linoleic acid incorporated in the sperm was compared, and behavior of cholesterol and effects of PKA and PKC inhibitors upon fatty acid-induced acrosome reaction were examined. METHODS: Semen was collected from a Duroc boar, and the metabolic activities of fatty acids in the spermatozoa were measured using radioactive compounds and thin layer chromatography. Cholesterol efflux was measured with a cholesterol determination assay kit. Participation of fatty acids on the AR through PKA and PKC pathways was evaluated using a specific inhibitor of these enzymes. RESULTS: Incorporation rate of 14C-oleic acid into the sperm lipids was significantly higher than that of 3H-linoleic acid (P < 0.05). The oxidation of 14C-oleic acid was higher in combined radiolabeling rather than in one. The highest amounts of 3H-linoleic acid and 14C-oleic acid were recovered mainly in the triglycerides and phospholipids fraction, and 14C-oleic acid distribution was higher than the 3H-linoleic acid in both labeled (P < 0.05) sperm lipids. In the 3H-linoleic and 14C-oleic acid combined radiolabeling, the incorporation rate of the radioactive fatty acids in all the lipid fractions increased 15 times more than the alone radiolabeling. Boar sperm utilize oleic acid to generate energy for hyperactivation (P < 0.05). Supplementation of arachidonic acid significantly increased (P < 0.05) cholesterol efflux in sperm. When spermatozoa were incubated with PKA or PKC inhibitors, there was a significant reduction of arachidonic acid-induced acrosome reaction (AR) (P < 0.05), and inhibition by PKA inhibitor is stronger than that by PKC inhibitor. CONCLUSIONS: Incorporation of unsaturated fatty acids, especially oleic acid, into triglycerides and phospholipids provides prerequisite energy for AR. Cholesterol efflux by arachidonic acid triggers AR. Arachidonic acid activated PKA and PKC pathway participate in induction of the AR.

Effect of selenium and vitamin E on acrosome reaction in porcine spermatozoa.

PURPOSE: Selenium (Se) and vitamin E (Vit-E), as an integral part of antioxidant systems, play an important role in the motility and acrosome reaction (AR) of mammalian spermatozoa. The purpose of this study was to investigate the effect of Se and Vit-E on motility, viability, AR and accumulation of ammonia in the culture medium during different incubation periods in porcine sperm. METHODS: Sperm samples were washed, swum-up and incubated at 37°C for 1 and 3 h in Sp-TALP medium supplemented with sodium selenite (SS), seleon l-methionine (SeMet) and Vit-E in the presence or absence of ammonia. Sperm motility was determined on the basis of movement quality examined by phase microscopy. Viability and AR of spermatozoa were assessed by Hoechst 33258 and chlortetracycline (CTC) staining technique, and accumulation of ammonia was measured by the indophenol method. The incorporation of 14C(U)-glucose was assessed with a liquid scintillation counter. RESULTS: In experiment 1, the sperm motility, viability, AR and incorporation of 14C(U)-glucose increased significantly (P < 0.05) in SS, SeMet and Vit-E (5, 5 µg/l and 1.0 mM, respectively) compared with the control. In experiment 2, treatment of the sperm with SeMet and SeMet + Vit-E in the presence of 300 µM ammonia also resulted in a significant increase (P < 0.05) in the rate of motility, viability, AR and incorporation of 14C(U)-glucose. In contrast, the accumulation of ammonia was reduced by SeMet and SeMet + Vit-E compared with the other treatments. CONCLUSIONS: These findings indicate that SeMet and SeMet + Vit-E may play an important role in reducing the accumulation of ammonia and subsequently in increasing the rate of AR and the utilization of glucose in porcine spermatozoa.

Mutations of the SYCP3 gene in women with recurrent pregnancy loss.

Aneuploidy, a chromosomal numerical abnormality in the conceptus or fetus, occurs in at least 5% of all pregnancies and is the leading cause of early pregnancy loss in humans. Accumulating evidence now suggests that the correct segregation of chromosomes is affected by events occurring in prophase during meiosis I. These events include homologous chromosome pairing, sister-chromatid cohesion, and meiotic recombination. In our current study, we show that mutations in SYCP3, a gene encoding an essential component of the synaptonemal complex that is central to the interaction of homologous chromosomes, are associated with recurrent pregnancy loss. Two out of 26 women with recurrent pregnancy loss of unknown cause were found to carry independent heterozygous nucleotide alterations in this gene, neither of which was present among a group of 150 fertile women. Analysis of transcripts from minigenes harboring each of these two mutations revealed that both affected normal splicing, possibly resulting in the production of C-terminally mutated proteins. The mutant proteins were found to interact with their wild-type counterpart in vitro and inhibit the normal fiber formation of the SYCP3 protein when coexpressed in a heterologous system. These data suggest that these mutations are likely to generate an aberrant synaptonemal complex in a dominant-negative manner and contribute to abnormal chromosomal behavior that might lead to recurrent miscarriage. Combined with the fact that similar mutations have been previously identified in two males with azoospermia, our current data suggest that sexual dimorphism in response to meiotic disruption occurs even in humans.

Effect of amino acids and dipeptides on the acrosome reaction and accumulation of ammonia in porcine spermatozoa.

Aim: The present study was designed to investigate the effect of amino acids and their dipeptides in the medium related to the urea cycle on the motility, viability, acrosome reaction (AR) and accumulation of ammonia in the medium over different incubation periods in porcine spermatozoa and to assess the utilization of glucose. Methods: Porcine spermatozoa were washed, swim-up and incubated at 37°C for 0-4 h in mTALP medium supplemented with 75-600 µmol/L ammonia. Amino acids (1.0 mmol) or their dipeptides (2.0 mmol) were added individually to the mTALP medium containing either no ammonia or 300 µmol/L of ammonia. The viability and AR of porcine spermatozoa were assessed using the triple-staining technique and the accumulation of ammonia in the medium was measured using the indophenol method. Results: The motility, viability and AR were adversely affected (P < 0.05) by concentrations of ammonia ≥300 µmol/L compared with the control. Supplementation of l-alanyl-l-glutamine (AlaGln), l-glycyl-l-glutamine (GlyGln) and AlaGln + GlyGln in the presence of 300 µmol/L ammonia significantly increase (P < 0.05) the rate of motility, viability, AR, incorporation, accumulation of ammonia and oxidation of 14C(U)-glucose compared with the ammonia supplement control. Conclusion: AlaGln and GlyGln in mTALP medium were more stable and effective than the individual amino acids in reducing the accumulation of ammonia, and subsequently increasing the rate of AR and the utilization of glucose in porcine spermatozoa. (Reprod Med Biol 2008; 7: 123-131).