P–549 What trophectoderm cells from mosaic embryos tell us about embryonic competence at the transcriptional level

2021 ◽  
Vol 36 (Supplement_1) ◽  
Author(s):  
A Martin ◽  
A Mercader ◽  
F Insua ◽  
L Escrich ◽  
N Grau ◽  
...  
Keyword(s):  
Inner Cell Mass ◽  
Single Cells ◽  
Cell Mass ◽  
Biological Significance ◽  
Enrichment Analysis ◽  
Chromosomal Mosaicism ◽  
Transcriptional Level ◽  
Rna Seq ◽  
Preimplantation Genetic Testing ◽  
Developmental Potential

Abstract Study question Does transcriptome of remaining trophectoderm (TE) reflect the developmental potential of mosaic blastocysts after preimplantation genetic testing for aneuploidy (PGT-A)? Summary answer: TE from low-degree mosaic (Low-mos) and high-degree mosaic (High-mos) blastocysts are transcriptionally equivalent, standing between euploid and aneuploid categories and displaying key deregulated developmental processes. What is known already Blastocysts classified as mosaic by PGT-A are associated with lower implantation and higher miscarriage rates than those classified as euploid, yet they still lead to healthy babies. Unveiling the true developmental identity of these embryos faces a dilemma: understanding to which extent they represent technical artefacts or whether they hold own potential to implant and give rise to normal pregnancies. Current RNA sequencing (RNA-seq) techniques allow for the determination of whole transcriptomic profiles even from single cells, which paves the way for the identification of new molecular keys of embryonic competence. Study design, size, duration Prospective study comparing RNA-seq data of remaining TE from blastocysts classified as euploid (n = 4), Low-mos (n = 5), High-mos (n = 4) and aneuploid (n = 6) by PGT-A. Participants were recruited between October 2018 and November 2019 at IVI-RMA Valencia. Participants/materials, setting, methods Chromosomal mosaicism was defined in the range 30%-<50% (Low-mos) and 50%-<70% (High-mos) using a next-generation sequencing (NGS) validated algorithm. Whole TE fractions were separately collected and processed for RNA-seq. Differentially expressed genes (DEGs) were calculated with DESeq2 package [Benjamini-Hochberg (BH)-adjusted p < 0.01 & abs(log2FoldChange)>2 significant]. Fgsea algorithm was used for enrichment analysis on Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways and Gene Ontology (GO) terms (BH-adjusted p < 0.01 significant). Main results and the role of chance For comparisons, TE from euploid blastocysts were used as control. At the gene level, 15 DEGs were found in Low-mos, 20 DEGs in High-mos, and 64 DEGs in aneuploid blastocysts. To address the functional implications of these differences, pathways significantly deregulated according to KEGG and GO categories were identified. TE from aneuploid blastocysts displayed significant downregulation in up to 115 KEGG and GO processes directly involved in processing and integrity maintenance of nuclear and mitochondrial genomes, a reflection of their aberrant chromosomal identity. In addition, TE from High-mos and Low-mos were transcriptionally equivalent (0 DEGs between both groups), with 23 overlapping KEGG and GO processes significantly downregulated compared with control. Importantly, main significantly-affected processes included mitotic sister chromatid segregation, NIK NF-kB activity, regulation of apoptosis, and pathways related to the biosynthesis and metabolism of proteins, fatty acids, carbohydrates and steroid hormones. These findings indicate that mosaic embryos comprise a unique developmental entity, which swims between the euploid and aneuploid waterfronts and may regulate survival by diverse mechanisms, including cell proliferation and apoptosis. Limitations, reasons for caution This is a descriptive, single-center study with limited sample size. TE fractions were obtained by micromanipulation, which may have led to potential cross-contamination with the inner cell mass. Wider implications of the findings: Transcriptomic equivalence between Low-mos and High-mos TE fractions questions the biological significance of inferring mosaicism degrees from single biopsies. Deregulated processes in these embryos support their reduced developmental and live birth potential, pointing to mechanisms that may mediate survival in the presence of aneuploid cells, as shown in the mouse. Trial registration number Not applicable

P-549 What trophectoderm cells from mosaic embryos tell us about embryonic competence at the transcriptional level

2021 ◽  
Vol 36 (Supplement_1) ◽  
Author(s):  
A Martin ◽  
A Mercader ◽  
F Insua ◽  
L Escrich ◽  
N Grau ◽  
...  
Keyword(s):  
Inner Cell Mass ◽  
Single Cells ◽  
Cell Mass ◽  
Biological Significance ◽  
Enrichment Analysis ◽  
Chromosomal Mosaicism ◽  
Transcriptional Level ◽  
Rna Seq ◽  
Preimplantation Genetic Testing ◽  
Developmental Potential

Abstract Study question Does transcriptome of remaining trophectoderm (TE) reflect the developmental potential of mosaic blastocysts after preimplantation genetic testing for aneuploidy (PGT-A)? Summary answer TE from low-degree mosaic (Low-mos) and high-degree mosaic (High-mos) blastocysts are transcriptionally equivalent, standing between euploid and aneuploid categories and displaying key deregulated developmental processes. What is known already Blastocysts classified as mosaic by PGT-A are associated with lower implantation and higher miscarriage rates than those classified as euploid, yet they still lead to healthy babies. Unveiling the true developmental identity of these embryos faces a dilemma: understanding to which extent they represent technical artefacts or whether they hold own potential to implant and give rise to normal pregnancies. Current RNA sequencing (RNA-seq) techniques allow for the determination of whole transcriptomic profiles even from single cells, which paves the way for the identification of new molecular keys of embryonic competence. Study design, size, duration Prospective study comparing RNA-seq data of remaining TE from blastocysts classified as euploid (n = 4), Low-mos (n = 5), High-mos (n = 4) and aneuploid (n = 6) by PGT-A. Participants were recruited between October 2018 and November 2019 at IVI-RMA Valencia. Participants/materials, setting, methods Chromosomal mosaicism was defined in the range 30%- < 50% (Low-mos) and 50%- < 70% (High-mos) using a next-generation sequencing (NGS) validated algorithm. Whole TE fractions were separately collected and processed for RNA-seq. Differentially expressed genes (DEGs) were calculated with DESeq2 package [Benjamini-Hochberg (BH)-adjusted p < 0.01 & abs(log2FoldChange)>2 significant]. Fgsea algorithm was used for enrichment analysis on Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways and Gene Ontology (GO) terms (BH-adjusted p < 0.01 significant). Main results and the role of chance For comparisons, TE from euploid blastocysts were used as control. At the gene level, 15 DEGs were found in Low-mos, 20 DEGs in High-mos, and 64 DEGs in aneuploid blastocysts. To address the functional implications of these differences, pathways significantly deregulated according to KEGG and GO categories were identified. TE from aneuploid blastocysts displayed significant downregulation in up to 115 KEGG and GO processes directly involved in processing and integrity maintenance of nuclear and mitochondrial genomes, a reflection of their aberrant chromosomal identity. In addition, TE from High-mos and Low-mos were transcriptionally equivalent (0 DEGs between both groups), with 23 overlapping KEGG and GO processes significantly downregulated compared with control. Importantly, main significantly-affected processes included mitotic sister chromatid segregation, NIK NF-kB activity, regulation of apoptosis, and pathways related to the biosynthesis and metabolism of proteins, fatty acids, carbohydrates and steroid hormones. These findings indicate that mosaic embryos comprise a unique developmental entity, which swims between the euploid and aneuploid waterfronts and may regulate survival by diverse mechanisms, including cell proliferation and apoptosis. Limitations, reasons for caution This is a descriptive, single-center study with limited sample size. TE fractions were obtained by micromanipulation, which may have led to potential cross-contamination with the inner cell mass. Wider implications of the findings Transcriptomic equivalence between Low-mos and High-mos TE fractions questions the biological significance of inferring mosaicism degrees from single biopsies. Deregulated processes in these embryos support their reduced developmental and live birth potential, pointing to mechanisms that may mediate survival in the presence of aneuploid cells, as shown in the mouse. Trial registration number Not applicable

The responsiveness of embryonic stem cells to alpha and beta interferons provides the basis of an inducible expression system for analysis of developmental control genes

1993 ◽  
Vol 13 (12) ◽  
pp. 7971-7976
Author(s):  
L M Whyatt ◽  
A Düwel ◽  
A G Smith ◽  
P D Rathjen
Keyword(s):  
Gene Expression ◽  
Inner Cell Mass ◽  
Es Cells ◽  
Expression System ◽  
Cell Mass ◽  
Embryonic Stem ◽  
Expression Vectors ◽  
Developmental Control ◽  
Developmental Potential

Embryonic stem (ES) cells, derived from the inner cell mass of the preimplantation mouse embryo, are used increasingly as an experimental tool for the investigation of early mammalian development. The differentiation of these cells in vitro can be used as an assay for factors that regulate early developmental decisions in the embryo, while the effects of altered gene expression during early embryogenesis can be analyzed in chimeric mice generated from modified ES cells. The experimental versatility of ES cells would be significantly increased by the development of systems which allow precise control of heterologous gene expression. In this paper, we report that ES cells are responsive to alpha and beta interferons (IFNs). This property has been exploited for the development of inducible ES cell expression vectors, using the promoter of the human IFN-inducible gene, 6-16. The properties of these vectors have been analyzed in both transiently and stably transfected ES cells. Expression was minimal or absent in unstimulated ES cells, could be stimulated up to 100-fold by treatment of the cells with IFN, and increased in linear fashion with increasing levels of IFN. High levels of induced expression were maintained for extended periods of time in the continuous presence of the inducing signal or following a 12-h pulse with IFN. Treatment of ES cells with IFN did not affect their growth or differentiation in vitro or compromise their developmental potential. This combination of features makes the 6-16-based expression vectors suitable for the functional analysis of developmental control control genes in ES cells.

P–530 The use of wide thresholds for detecting intermediate chromosomal CNV up to 80% doesn’t improve PGT-A ability to discriminate true mosaic from uniformly aneuploid embryos

2021 ◽  
Vol 36 (Supplement_1) ◽  
Author(s):  
L Girardi ◽  
M Serdaroğulları ◽  
C Patassini ◽  
S Caroselli ◽  
M Costa ◽  
...  
Keyword(s):  
Inner Cell Mass ◽  
False Negative ◽  
Cell Mass ◽  
Categorical Variables ◽  
P Value ◽  
Sequencing Data ◽  
Preimplantation Genetic Testing ◽  
Exact Test ◽  
Institutional Review ◽  
Wide Range

Abstract Study question What is the effect of varying diagnostic thresholds on the accuracy of Next Generation Sequencing (NGS)-based preimplantation genetic testing for aneuploidies (PGT-A)? Summary answer When single trophectoderm biopsies are tested, the employment of 80% upper threshold increases mosaic calls and false negative aneuploidy results compared to more stringent thresholds. What is known already Trophectoderm (TE) biopsy coupled with NGS-based PGT-A technologies are able to accurately predict Inner Cell Mass’ (ICM) constitution when uniform whole chromosome aneuploidies are considered. However, minor technical and biological inconsistencies in NGS procedures and biopsy specimens can result in subtle variability in analytical results. In this context, the stringency of thresholds employed for diagnostic calls can lead to incorrect classification of uniformly aneuploid embryos into the mosaic category, ultimately affecting PGT-A accuracy. In this study, we evaluated the diagnostic predictivity of different aneuploidy classification criteria by employing blinded analysis of chromosome copy number values (CNV) in multifocal blastocyst biopsies. Study design, size, duration The accuracy of different aneuploidy diagnostic cut-offs was assessed comparing chromosomal CNV in intra-blastocysts multifocal biopsies. Enrolled embryos were donated for research between June and September 2020. The Institutional Review Board at the Near East University approved the study (project: YDU/20l9/70–849). Embryos diagnosed with uniform chromosomal alterations (single or multiple) in their clinical TE biopsy (n = 27) were disaggregated into 5 portions: the ICM and 4 TE biopsies. Overall, 135 specimens were collected and analysed. Participants/materials, setting, methods Twenty-seven donated blastocysts were warmed and disaggregated in TE biopsies and ICM (n = 135 biopsies). PGT-A analysis was performed using Ion ReproSeq PGS kit and Ion S5 sequencer (ThermoFisher). Sequencing data were blindly analysed with Ion-Reporter software. Intra-blastocyst comparison of raw NGS data was performed employing different thresholds commonly used for aneuploidy classification. CNV for each chromosome were reported as aneuploid according to 70% or 80% thresholds. Categorical variables were compared using Fisher’s exact test. Main results and the role of chance In this study, a total of 50 aneuploid patterns in 27 disaggregated embryos were explored. Single TE biopsy results were considered as true positive when they displayed the same alteration detected in the ICM at levels above the 70% or 80% thresholds. Alternatively, alterations detected in the euploid or mosaic range were considered as false negative aneuploidy results. When the 70% threshold was applied, aneuploidy findings were confirmed in 94.5% of TE biopsies analyzed (n = 189/200; 95%CI=90.37–37.22), while 5.5% showed a mosaic profile (50–70%) but uniformly abnormal ICM. Positive (PPV) and negative predictive value (NPV) per chromosome were 100.0% (n = 189/189; 95%CI=98.07–100.00) and 99.5% (n = 2192/2203; 95%CI=99.11–99.75) respectively. When the upper cut-off was experimentally placed at 80% of abnormal cells, a significant decrease (p-value=0.0097) in the percentage of confirmed aneuploid calls was observed (86.5%; n = 173/200; 95%CI=80.97–90.91), resulting in mosaicism overcalling, especially in the high range (50–80%). Less stringent thresholds led to extremely high PPV (100.0%; n = 173/173; 95%CI=97.89–100.00), while NPV decreased to 98.8% (n = 2192/2219; 95%CI=98.30–99.23). Furthermore, no additional true mosaic patterns were identified with the use of wide range thresholds for aneuploidy classification. Limitations, reasons for caution This approach involved the analysis of aneuploidy CNV thresholds at the embryo level and lacked from genotyping-based confirmation analysis. Moreover, aneuploid embryos with known meiotic partial deletion/duplication were not included. Wider implications of the findings: The use of wide thresholds for detecting intermediate chromosomal CNV up to 80% doesn’t improve PGT-A ability to discriminate true mosaic from uniformly aneuploid embryos, lowering overall diagnostic accuracy. Hence, a proportion of the embryos diagnosed as mosaic using wide calling thresholds may actually be uniformly aneuploid and inadvertently transferred. Trial registration number N/A

Interactions of blastomeres suggest changes in cell surface adhesiveness during the formation of inner cell mass and trophectoderm in the preimplantation mouse embryo

Development ◽  
1982 ◽  
Vol 70 (1) ◽  
pp. 133-152
Author(s):  
Susan J. Kimber ◽  
M. Azim ◽  
H. Surani ◽  
Sheila C. Barton
Keyword(s):  
Inner Cell Mass ◽  
Single Cells ◽  
Cell Mass ◽  
Cell Stage ◽  
Trophectoderm Cells ◽  
Adhesive Surface ◽  
Preimplantation Mouse Embryo ◽  
Divergent Differentiation ◽  
Preimplantation Mouse ◽  
The Difference

Whole 8-cell morulae can be aggregated with isolated inner cell masses from blastocysts. On examining semithin light microscope sections of such aggregates we found that cells of the morula changed shape and spread over the surface of the ICM, thus translocating it to the inside of the aggregate. Using single cells from 8-cell embryos in combination with single cells from other stage embryos or isolated ICMs we show that 1/8 blastomeres spread over other cells providing a suitably adhesive surface. The incidence of spreading is high with inner cells from 16-cell embryos (56 %) and 32-cell embryos (62%) and isolated inner cell masses (64%). In contrast, the incidence of spreading of 1/8 blastomeres is low over outer cells from 16-cell embryos (26%) and 32-cell embryos (13%). Blastomeres from 8-cell embryos do not spread over unfertilized 1-cell eggs, 1/2 or 1/4 cells or trophectoderm cells contaminating isolated ICMs. When 1/8 cells are aggregated in pairs they flatten on one another (equal spreading) as occurs at compaction in whole 8-cell embryos. However, if 1/8 is allowed to divide to 2/16 in culture one of the cells engulfs the other (51-62/ pairs). Based on the ideas of Holtfreter (1943) and Steinberg (1964,1978) these results are interpreted to indicate an increase in adhesiveness at the 8-cell stage as well as cytoskeletal mobilization. Following the 8-cell stage there is an increase in adhesiveness of inside cells while the outside cells decrease in adhesiveness. The difference in adhesiveness between inside and outside cells in late morulae is probably central to the divergent differentiation of (inner) ICM and (outer) trophectoderm cell populations.

scholarly journals Base editing in bovine embryos reveals a species-specific role of SOX2 in regulation of pluripotency

2021 ◽  
Author(s):  
Lei Luo ◽  
Yan Shi ◽  
Huanan Wang ◽  
Zizengchen Wang ◽  
Yanna Dang ◽  
...  
Keyword(s):  
Inner Cell Mass ◽  
Cell Mass ◽  
Rna Seq ◽  
Bovine Embryos ◽  
Base Editing ◽  
Sox2 Expression ◽  
Nanog Expression ◽  
Species Specific ◽  
Lineage Specific Genes

The emergence of the first three lineages during development are orchestrated by a network of transcription factors, which are best characterized in mice. However, the role and regulation of these factors are not completely conserved in other mammals, including human and cattle. Here, we establish a gene inactivation system by introducing premature codon with cytosine base editor in bovine embryos with a robust efficiency. Of interest, SOX2 is universally localized in early blastocysts but gradually restricted into the inner cell mass in cattle. SOX2 knockout results in a failure of the establishment of pluripotency. Indeed, OCT4 level is significantly reduced and NANOG was barely detectable. Furthermore, the formation of primitive endoderm is compromised with few SOX17 positive cells. Single embryo RNA-seq reveals a dysregulation of 2074 genes, among which 90% are up-regulated in SOX2-null blastocysts. Intriguingly, more than a dozen lineage-specific genes, including OCT4 and NANOG, are down-regulated. Moreover, SOX2 expression is sustained in the trophectoderm in absence of CDX2 in bovine late blastocysts. Overall, we propose that SOX2 is dispensable for OCT4 and NANOG expression and disappearance of SOX2 in the trophectoderm depends on CDX2 in cattle, which are all in sharp contrast with results in mice.

scholarly journals Three-Dimensional Live Imaging of Bovine Preimplantation Embryos: A New Method for IVF Embryo Evaluation

2021 ◽  
Vol 8 ◽  
Author(s):  
Yasumitsu Masuda ◽  
Ryo Hasebe ◽  
Yasushi Kuromi ◽  
Masayoshi Kobayashi ◽  
Kanako Urataki ◽  
...  
Keyword(s):  
Embryo Transfer ◽  
Inner Cell Mass ◽  
Cell Mass ◽  
Three Dimensional ◽  
Preimplantation Embryos ◽  
Infrared Light ◽  
Bovine Embryo ◽  
Bovine Embryos ◽  
Cell Stage ◽  
Developmental Potential

Conception rates for transferred bovine embryos are lower than those for artificial insemination. Embryo transfer (ET) is widely used in cattle but many of the transferred embryos fail to develop, thus, a more effective method for selecting bovine embryos suitable for ET is required. To evaluate the developmental potential of bovine preimplantation embryos (2-cell stage embryos and blastocysts), we have used the non-invasive method of optical coherence tomography (OCT) to obtain live images. The images were used to evaluate 22 parameters of blastocysts, such as the volume of the inner cell mass and the thicknesses of the trophectoderm (TE). Bovine embryos were obtained by in vitro fertilization (IVF) of the cumulus-oocyte complexes aspirated by ovum pick-up from Japanese Black cattle. The quality of the blastocysts was examined under an inverted microscope and all were confirmed to be Code1 according to the International Embryo Transfer Society standards for embryo evaluation. The OCT images of embryos were taken at the 2-cell and blastocyst stages prior to the transfer. In OCT, the embryos were irradiated with near-infrared light for a few minutes to capture three-dimensional images. Nuclei of the 2-cell stage embryos were clearly observed by OCT, and polynuclear cells at the 2-cell stage were also clearly found. With OCT, we were able to observe embryos at the blastocyst stage and evaluate their parameters. The conception rate following OCT (15/30; 50%) is typical for ETs and no newborn calves showed neonatal overgrowth or died, indicating that the OCT did not adversely affect the ET. A principal components analysis was unable to identify the parameters associated with successful pregnancy, while by using hierarchical clustering analysis, TE volume has been suggested to be one of the parameters for the evaluation of bovine embryo. The present results show that OCT imaging can be used to investigate time-dependent changes of IVF embryos. With further improvements, it should be useful for selecting high-quality embryos for transfer.

P–516 Evidence for self-correction in preimplantation embryos by comparative molecular karyotyping of blastocoele fluid, trophectoderm and inner cell mass

2021 ◽  
Vol 36 (Supplement_1) ◽  
Author(s):  
D Zhigalina ◽  
N Skryabin ◽  
O Kanbekova ◽  
V Artyukhova ◽  
A Svetlakov ◽  
...  
Keyword(s):  
Inner Cell Mass ◽  
Cell Mass ◽  
Morphological Characteristics ◽  
Preimplantation Embryos ◽  
Molecular Karyotyping ◽  
Embryonic Cells ◽  
Developmental Potential ◽  
Positive Correlation ◽  
Registration Number ◽  
Molecular Karyotype

Abstract Study question Does the molecular karyotype of the cell-free DNA (cfDNA) from the blastocyst fluid (BF) can predict the efficiency of self-correction of karyotype of preimplantation embryo? Summary answer Detection of aneuploidies in the BF potentially can point out on effective self-correction of blastocyst karyotype and consequently on high developmental potential of mosaic embryos. What is known already Correction of aneuploidies in the preimplantation embryos can be provided by several mechanisms, including apoptosis. The predominant death of aneuploid cells was demonstrated in mouse embryos (Bolton, 2016). A positive correlation was also shown between the concentration of cfDNA from the BF of human blastocyst and the morphology of the embryo, as well as between the activity of caspase–3 and the concentration of cfDNA (Rule, 2018). The incidence of failed amplification after WGA being significantly higher among euploid blastocysts (Magli, 2019). The capacity of abnormal cells extruding into the BF would be related to the embryo development potential (Gianaroli, 2019). Study design, size, duration This is a prospective observational study of thirty-one Day 5 human blastocysts. Cryopreserved blastocysts were received after treatment cycles at the IVF Center with informed consent obtained from couples. The average age of 15 women was 32.25±5 years. The morphological characteristics of blastocysts were estimated in accordance with the Gardner classification (Gardner, Schoolcraft, 1999). The procedure of BF aspiration and trophectoderm (TE) and ICM cells separation of the blastocysts was previously described (Tsuiko, 2018). Participants/materials, setting, methods WGA was performed by PicoPLEX kit (Rubicon Genomics, USA) or REPLI-g Mini kit (Qiagen) according to manufacturer’s protocols. The DNA of the BF, ICM and TE were analyzed separately using cCGH, aCGH and NGS. SurePrint G3 Human CGH Microarrays (8x60K, Agilent Technologies) were used according to the manufacturer’s recommendations. Image analysis was done using ISIS (v.5.5) (Metasystems) and Agilent CytoGenomics Software (v.3). VeriSeq™ PGS Kit - MiSeq® System (Illumina) was used for NGS. Main results and the role of chance Molecular karyotypes of all three samples - BF, ICM and TE, were obtained for 23 (74.2%) blastocysts. A correlation between the woman’s age and the number of aneuploidies in cfDNA (p = 0.0009) was found. A positive correlation may indicate that the number of aneuploidies in the embryonic cells increases with the age of a woman, however, the embryonic karyotype undergoes self-correcting through the elimination of aneuploid cells. It was noted that well-developing blastocysts (groups 4–5, according to Gardner’s classification) had fewer aneuploidies in ICM (p = 0.0141) and TE (p = 0.0436). In contrast, there was a tendency to an increase in the number of aneuploidies in the BF during blastocysts transition from stage 3 to 5 (p = 0.3542). We assessed the relationship between the number of aneuploidies in groups of blastocysts with different characteristics of ICM (groups “A” and “B” according to Gardner’s classification). These groups significantly differ in the number of aneuploidies in cfDNA (p = 0.0352), although the statistically significant differences between the number of aneuploidies in ICM (p = 0.5992) and in TE (p = 0.5934) was not detected. Thus, higher-quality embryos in terms of ICM morphology contain more abnormalities in the BF, since in this group the elimination of aneuploid cells is more efficient. Limitations, reasons for caution The number of embryos is limited in this study. More comprehensive studies are required to confirm the observed tendency. Wider implications of the findings: Aneuploid cells elimination can be a cause of increasing cfDNA concentration in the BF, which may be a marker of the viability of mosaic embryos when it is necessary to decide on mosaic embryo transfer. This study was supported by the RFBR (15–04–08265) and by the RSF (20–74–00064). Trial registration number Not applicable

Investigation of cell lineage and differentiation in the extraembryonic endoderm of the mouse embryo

Development ◽  
1982 ◽  
Vol 68 (1) ◽  
pp. 175-198
Author(s):  
R. L. Gardner
Keyword(s):  
Inner Cell Mass ◽  
Cell Mass ◽  
Cell Lineage ◽  
Early Embryo ◽  
Visceral Endoderm ◽  
Primitive Endoderm ◽  
Developmental Potential ◽  
Extraembryonic Endoderm ◽  
Parietal Endoderm ◽  
Endodermal Cells

The technique of injecting genetically labelled cells into blastocysts was used in an attempt to determine whether the parietal and visceral endoderm originate from the same or different cell populations in the early embryo. When the developmental potential of 5th day primitive ectoderm and primitive endoderm cells was compared thus, only the latter were found to colonize the extraembryonic endoderm. Furthermore, single primitive endoderm cells yielded unequivocal colonization of both the parietal and the visceral endoderm in a proportion of chimaeras. However, in the majority of primitive endodermal chimaeras, donor cells were detected in the parietal endoderm only, cases of exclusively visceral colonization being rare. Visceral endoderm cells from 6th and 7th day post-implantation embryos also exhibited a striking tendency to contribute exclusively to the parietal endoderm following blastocyst injection. The above findings lend no support to a recent proposal that parietal and visceral endoderm are derived from different populations of inner cell mass cells. Rather, they suggest that the two extraembryonic endoderm layers originate from a common pool of primitive endoderm cells whose direction of differentiation depends on their interactions with non-endodermal cells.

scholarly journals Lipid Stores and Lipid Metabolism Associated Gene Expression in Porcine and Bovine Parthenogenetic Embryos Revealed by Fluorescent Staining and RNA-seq

2020 ◽  
Vol 21 (18) ◽  
pp. 6488
Author(s):  
Arkadiusz Kajdasz ◽  
Ewelina Warzych ◽  
Natalia Derebecka ◽  
Zofia E. Madeja ◽  
Dorota Lechniak ◽  
...  
Keyword(s):  
Gene Expression ◽  
Lipid Metabolism ◽  
Inner Cell Mass ◽  
Mammalian Species ◽  
Cell Mass ◽  
Blastocyst Stage ◽  
Preimplantation Embryos ◽  
Rna Seq ◽  
Expression Of Genes ◽  
Bovine Blastocyst

Compared to other mammalian species, porcine oocytes and embryos are characterized by large amounts of lipids stored mainly in the form of droplets in the cytoplasm. The amount and the morphology of lipid droplets (LD) change throughout the preimplantation development, however, relatively little is known about expression of genes involved in lipid metabolism of early embryos. We compared porcine and bovine blastocyst stage embryos as well as dissected inner cell mass (ICM) and trophoblast (TE) cell populations with regard to lipid droplet storage and expression of genes functionally annotated to selected lipid gene ontology terms using RNA-seq. Comparing the number and the volume occupied by LD between bovine and porcine blastocysts, we have found significant differences both at the level of single embryo and a single blastomere. Aside from different lipid content, we found that embryos regulate the lipid metabolism differentially at the gene expression level. Out of 125 genes, we found 73 to be differentially expressed between entire porcine and bovine blastocyst, and 36 and 51 to be divergent between ICM and TE cell lines. We noticed significant involvement of cholesterol and ganglioside metabolism in preimplantation embryos, as well as a possible shift towards glucose, rather than pyruvate dependence in bovine embryos. A number of genes like DGAT1, CD36 or NR1H3 may serve as lipid associated markers indicating distinct regulatory mechanisms, while upregulated PLIN2, APOA1, SOAT1 indicate significant function during blastocyst formation and cell differentiation in both models.

6 ANEUPLOIDY TOLERANCE IN RHESUS MACAQUE PRE-IMPLANTATION EMBRYOS VIA MICRONUCLEI FORMATION, CELLULAR FRAGMENTATION, AND BLASTOMERE EXCLUSION

2017 ◽  
Vol 29 (1) ◽  
pp. 110 ◽  
Author(s):  
B. L. Daughtry ◽  
J. L. Rosenkrantz ◽  
N. Lazar ◽  
N. Redmayne ◽  
K. A. Nevonen ◽  
...  
Keyword(s):  
Rhesus Macaque ◽  
Inner Cell Mass ◽  
Cell Mass ◽  
Time Lapse ◽  
Confocal Imaging ◽  
Chromosomal Mosaicism ◽  
Human Embryos ◽  
Cleavage Stage ◽  
Chromosomal Breakage

A primary contributor to in vitro fertilization (IVF) failure is the presence of unbalanced chromosomes in pre-implantation embryos. Previous array-based and next-generation sequencing (NGS) studies determined that ~50 to 80% of human embryos are aneuploid at the cleavage stage. During early mitotic divisions, many human embryos also sequester mis-segregated chromosomes into micronuclei and concurrently undergo cellular fragmentation. We hypothesised that cellular fragmentation represents a response to mis-segregated chromosomes that are encapsulated into micronuclei. Here, we utilised the rhesus macaque pre-implantation embryo as a model to study human embryonic aneuploidy using a combination of EevaTM time-lapse imaging for evaluating cell divisions, single-cell/-fragment DNA-Sequencing (DNA-Seq), and confocal microscopy of nuclear structures. Results from our time-lapse image analysis demonstrated that there are considerable differences in the timing of the first and third mitotic divisions between rhesus blastocysts and those that arrested before this stage in development (P < 0.01; ANOVA). By examining the chromosome content of each blastomere from cleavage stage embryos via DNA-Seq, we determined that rhesus embryos have an aneuploidy frequency up to ~62% (N = 26) with several embryos exhibiting chromosomal mosaicism between blastomeres (N = 6). Certain blastomeres also exhibited reciprocal whole chromosomal gains or losses, indicating that these embryos had undergone mitotic non-disjunction early in development. In addition, findings of reciprocal sub-chromosomal deletions/duplications among blastomeres suggest that chromosomal breakage had occurred in some embryos as well. Embryo immunostaining for the nuclear envelope protein, LAMIN-B1, demonstrated that fragmented cleavage-stage rhesus embryos often contain micronuclei and that cellular fragments can enclose DNA. Our DNA-Seq analysis confirmed that cellular fragments might encapsulate whole and/or partial chromosomes lost from blastomeres. When embryos were immunostained with gamma-H2AX, a marker of chromatin fragility, we observed distinct foci solely in micronuclei and DNA-containing cellular fragments. This suggests that micronuclei may be ejected from blastomeres through the process of cellular fragmentation and, once sequestered, these mis-segregated chromosomes become highly unstable and undergo DNA degradation. Finally, we also observed that ~10% of embryos prevented cellular fragments or large blastomeres from incorporating into the inner cell mass or trophectoderm at the blastocyst stage (n = 5). Upon confocal imaging, multiple nuclei and intense gamma-H2AX foci were found in a large unincorporated blastomere in one of the blastocysts. Altogether, our findings demonstrate that the rhesus embryo responds to segregation errors by eliminating chromosome-containing micronuclei via cellular fragmentation and/or selecting against aneuploid blastomeres that fail to divide during pre-implantation development with significant implications for human IVF.

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