scholarly journals Epigenetic Modification Affecting Expression of Cell Polarity and Cell Fate Genes to Regulate Lineage Specification in the Early Mouse Embryo

2010 ◽  
Vol 21 (15) ◽  
pp. 2649-2660 ◽  
Author(s):  
David-Emlyn Parfitt ◽  
Magdalena Zernicka-Goetz
Keyword(s):  
Cell Fate ◽  
Cell Polarity ◽  
Mouse Embryo ◽  
Inner Cell Mass ◽  
Epigenetic Modification ◽  
Cell Mass ◽  
Time Lapse ◽  
Cell Polarization ◽  
Asymmetric Divisions

Formation of inner and outer cells of the mouse embryo distinguishes pluripotent inner cell mass (ICM) from differentiating trophectoderm (TE). Carm1, which methylates histone H3R17 and R26, directs cells to ICM rather that TE. To understand the mechanism by which this epigenetic modification directs cell fate, we generated embryos with in vivo–labeled cells of different Carm1 levels, using time-lapse imaging to reveal dynamics of their behavior, and related this to cell polarization. This shows that Carm1 affects cell fate by promoting asymmetric divisions, that direct one daughter cell inside, and cell engulfment, where neighboring cells with lower Carm1 levels compete for outside positions. This is associated with changes to the expression pattern and spatial distribution of cell polarity proteins: Cells with higher Carm1 levels show reduced expression and apical localization of Par3 and a dramatic increase in expression of PKCII, antagonist of the apical protein aPKC. Expression and basolateral localization of the mouse Par1 homologue, EMK1, increases concomitantly. Increased Carm1 also reduces Cdx2 expression, a transcription factor key for TE differentiation. These results demonstrate how the extent of a specific epigenetic modification could affect expression of cell polarity and fate-determining genes to ensure lineage allocation in the mouse embryo.

scholarly journals Mechanism of cell polarisation and first lineage segregation in the human embryo

2020 ◽  
Author(s):  
Meng Zhu ◽  
Marta N. Shahbazi ◽  
Angel Martin ◽  
Chuanxin Zhang ◽  
Berna Sozen ◽  
...  
Keyword(s):  
Cell Fate ◽  
Mouse Embryo ◽  
Human Embryo ◽  
Inner Cell Mass ◽  
Cell Mass ◽  
Time Lapse ◽  
Nuclear Accumulation ◽  
Human Embryos ◽  
Cell Stage ◽  
Cellular Domain

AbstractThe formation of differential cell lineages in the mammalian blastocyst from the totipotent zygote is crucial for implantation and the success of the whole pregnancy. The first lineage segregation generates the polarised trophectoderm (TE) tissue, which forms the placenta, and the apolar inner cell mass (ICM), which mainly gives rise to all foetal tissues and also the yolk sac1–3. The mechanism underlying this cell fate segregation has been extensively studied in the mouse embryo4,5. However, when and how it takes place in the human embryo remains unclear. Here, using time-lapse imaging and 325 surplus human embryos, we provide a detailed characterisation of morphological events and transcription factor expression and localisation to understand how they lead to the first lineage segregation in human embryogenesis. We show that the first lineage segregation of the human embryo is triggered by cell polarisation that occurs at the 8-cell stage in two sequential steps. In the first step, F-actin becomes apically polarised concomitantly with embryo compaction. In the second step, the Par complex becomes polarised to form the apical cellular domain. Mechanistically, we show that activation of Phospholipase C (PLC) triggers actin polarisation and is therefore essential for apical domain formation, as is the case in mouse embryos6. Finally, we show that, in contrast to the mouse embryo, the key extra-embryonic determinant GATA37,8 is expressed not only in extra-embryonic lineage precursors upon blastocyst formation. However, the cell polarity machinery enhances the expression and nuclear accumulation of GATA3. In summary, our results demonstrate for the first time that cell polarisation reinforces the first lineage segregation in the human embryo.

scholarly journals Role of Cdx2 and cell polarity in cell allocation and specification of trophectoderm and inner cell mass in the mouse embryo

2008 ◽  
Vol 22 (19) ◽  
pp. 2692-2706 ◽  
Author(s):  
A. Jedrusik ◽  
D.-E. Parfitt ◽  
G. Guo ◽  
M. Skamagki ◽  
J. B. Grabarek ◽  
...  
Keyword(s):  
Cell Polarity ◽  
Mouse Embryo ◽  
Inner Cell Mass ◽  
Cell Mass

scholarly journals The enigmatic morula: mechanisms of development, cell fate determination, self-correction and implications for ART

2019 ◽  
Vol 25 (4) ◽  
pp. 422-438 ◽  
Author(s):  
Giovanni Coticchio ◽  
Cristina Lagalla ◽  
Roger Sturmey ◽  
Francesca Pennetta ◽  
Andrea Borini
Keyword(s):  
Cell Fate ◽  
Cell Polarity ◽  
Assisted Reproduction ◽  
Cell Biology ◽  
Inner Cell Mass ◽  
Cell Mass ◽  
Preimplantation Development ◽  
Embryo Viability ◽  
Cellular Processes ◽  
Morula Stage

Abstract BACKGROUND Assisted reproduction technology offers the opportunity to observe the very early stages of human development. However, due to practical constraints, for decades morphological examination of embryo development has been undertaken at a few isolated time points at the stages of fertilisation (Day 1), cleavage (Day 2–3) and blastocyst (Day 5–6). Rather surprisingly, the morula stage (Day 3–4) has been so far neglected, despite its involvement in crucial cellular processes and developmental decisions. OBJECTIVE AND RATIONALE The objective of this review is to collate novel and unsuspected insights into developmental processes occurring during formation of the morula, highlighting the key importance of this stage for a better understanding of preimplantation development and an improvement of ART. SEARCH METHODS PubMed was used to search the MEDLINE database for peer-reviewed English-language original articles and reviews concerning the morula stage in mammals. Searches were performed by adopting ‘embryo’, ‘morula’, ‘compaction’, ‘cell fate’ and ‘IVF/assisted reproduction’ as main terms, in association with other keywords expressing concepts relevant to the subject (e.g. cell polarity). The most relevant publications, i.e. those concerning major phenomena occurring during formation of the morula in established experimental models and the human species, were assessed and discussed critically. OUTCOMES Novel live cell imaging technologies and cell biology studies have extended our understanding of morula formation as a key stage for the development of the blastocyst and determination of the inner cell mass (ICM) and the trophectoderm (TE). Cellular processes, such as dynamic formation of filopodia and cytoskeleton-mediated zippering cell-to-cell interactions, intervene to allow cell compaction (a geometrical requisite essential for development) and formation of the blastocoel, respectively. At the same time, differential orientation of cleavage planes, cell polarity and cortical tensile forces interact and cooperate to position blastomeres either internally or externally, thereby influencing their cellular fate. Recent time lapse microscopy (TLM) observations also suggest that in the human the process of compaction may represent an important checkpoint for embryo viability, through which chromosomally abnormal blastomeres are sensed and eliminated by the embryo. WIDER IMPLICATIONS In clinical embryology, the morula stage has been always perceived as a ‘black box’ in the continuum of preimplantation development. This has dictated its virtual exclusion from mainstream ART procedures. Recent findings described in this review indicate that the morula, and the associated process of compaction, as a crucial stage not only for the formation of the blastocyst, but also for the health of the conceptus. This understanding may open new avenues for innovative approaches to embryo manipulation, assessment and treatment.

scholarly journals The Murine Ortholog of Notchless, a Direct Regulator of the Notch Pathway in Drosophila melanogaster, Is Essential for Survival of Inner Cell Mass Cells

2006 ◽  
Vol 26 (9) ◽  
pp. 3541-3549 ◽  
Author(s):  
Sarah Cormier ◽  
Stéphanie Le Bras ◽  
Céline Souilhol ◽  
Sandrine Vandormael-Pournin ◽  
Béatrice Durand ◽  
...  
Keyword(s):  
Drosophila Melanogaster ◽  
Notch Signaling ◽  
Cell Fate ◽  
Inner Cell Mass ◽  
Cell Mass ◽  
Notch Pathway ◽  
Notch Signaling Pathway ◽  
Direct Regulator

ABSTRACT Notch signaling is an evolutionarily conserved pathway involved in intercellular communication and is essential for proper cell fate choices. Numerous genes participate in the modulation of the Notch signaling pathway activity. Among them, Notchless (Nle) is a direct regulator of the Notch activity identified in Drosophila melanogaster. Here, we characterized the murine ortholog of Nle and demonstrated that it has conserved the ability to modulate Notch signaling. We also generated mice deficient for mouse Nle (mNle) and showed that its disruption resulted in embryonic lethality shortly after implantation. In late mNle −/− blastocysts, inner cell mass (ICM) cells died through a caspase 3-dependent apoptotic process. Most deficient embryos exhibited a delay in the temporal down-regulation of Oct4 expression in the trophectoderm (TE). However, mNle-deficient TE was able to induce decidual swelling in vivo and properly differentiated in vitro. Hence, our results indicate that mNle is mainly required in ICM cells, being instrumental for their survival, and raise the possibility that the death of mNle-deficient embryos might result from abnormal Notch signaling during the first steps of development.

scholarly journals The differential response to Fgf signalling in cells internalized at different times influences lineage segregation in preimplantation mouse embryos

Open Biology ◽  
2013 ◽  
Vol 3 (11) ◽  
pp. 130104 ◽  
Author(s):  
Samantha A. Morris ◽  
Sarah J. L. Graham ◽  
Agnieszka Jedrusik ◽  
Magdalena Zernicka-Goetz
Keyword(s):  
Cell Fate ◽  
Inner Cell Mass ◽  
Cell Mass ◽  
Developmental History ◽  
Cell Stage ◽  
Developmental Potential ◽  
Relative Contribution ◽  
Asymmetric Divisions ◽  
Preimplantation Mouse ◽  
Fgf Signalling

Lineage specification in the preimplantation mouse embryo is a regulative process. Thus, it has been difficult to ascertain whether segregation of the inner-cell-mass (ICM) into precursors of the pluripotent epiblast (EPI) and the differentiating primitive endoderm (PE) is random or influenced by developmental history. Here, our results lead to a unifying model for cell fate specification in which the time of internalization and the relative contribution of ICM cells generated by two waves of asymmetric divisions influence cell fate. We show that cells generated in the second wave express higher levels of Fgfr2 than those generated in the first, leading to ICM cells with varying Fgfr2 expression. To test whether such heterogeneity is enough to bias cell fate, we upregulate Fgfr2 and show it directs cells towards PE. Our results suggest that the strength of this bias is influenced by the number of cells generated in the first wave and, mostly likely, by the level of Fgf signalling in the ICM. Differences in the developmental potential of eight-cell- and 16-cell-stage outside blastomeres placed in the inside of chimaeric embryos further support this conclusion. These results unite previous findings demonstrating the importance of developmental history and Fgf signalling in determining cell fate.

Use of F9 teratocarcinoma STEM cells to study cell-matrix interactions in the early mouse embryo

1992 ◽  
Vol 50 (1) ◽  
pp. 602-603
Author(s):  
Marc Lenburg ◽  
Rulang Jiang ◽  
Lengya Cheng ◽  
Laura Grabel
Keyword(s):  
Mouse Embryo ◽  
Inner Cell Mass ◽  
Cell Mass ◽  
Cell Types ◽  
Embryoid Bodies ◽  
F9 Cells ◽  
Cell Matrix ◽  
Matrix Interactions ◽  
Cell Matrix Interactions ◽  
F9 Teratocarcinoma

We are interested in defining the cell-cell and cell-matrix interactions that help direct the differentiation of extraembryonic endoderm in the peri-implantation mouse embryo. At the blastocyst stage the mouse embryo consists of an outer layer of trophectoderm surrounding the fluid-filled blastocoel cavity and an eccentrically located inner cell mass. On the free surface of the inner cell mass, facing the blastocoel cavity, a layer of primitive endoderm forms. Primitive endoderm then generates two distinct cell types; parietal endoderm (PE) which migrates along the inner surface of the trophectoderm and secretes large amounts of basement membrane components as well as tissue-type plasminogen activator (tPA), and visceral endoderm (VE), a columnar epithelial layer characterized by tight junctions, microvilli, and the synthesis and secretion of α-fetoprotein. As these events occur after implantation, we have turned to the F9 teratocarcinoma system as an in vitro model for examining the differentiation of these cell types. When F9 cells are treated in monolayer with retinoic acid plus cyclic-AMP, they differentiate into PE. In contrast, when F9 cells are treated in suspension with retinoic acid, they form embryoid bodies (EBs) which consist of an outer layer of VE and an inner core of undifferentiated stem cells. In addition, we have established that when VE containing embryoid bodies are plated on a fibronectin coated substrate, PE migrates onto the matrix and this interaction is inhibited by RGDS as well as antibodies directed against the β1 integrin subunit. This transition is accompanied by a significant increase in the level of tPA in the PE cells. Thus, the outgrowth system provides a spatially appropriate model for studying the differentiation and migration of PE from a VE precursor.

scholarly journals Cell fate clusters in ICM organoids arise from cell fate heredity and division: a modelling approach

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Tim Liebisch ◽  
Armin Drusko ◽  
Biena Mathew ◽  
Ernst H. K. Stelzer ◽  
Sabine C. Fischer ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Cell Division ◽  
Cell Fate ◽  
Inner Cell Mass ◽  
Cell Mass ◽  
Cell Lineage ◽  
Cell Fate Decision ◽  
Cell Fate Decisions ◽  
Chemical Signalling ◽  
Fate Decision

AbstractDuring the mammalian preimplantation phase, cells undergo two subsequent cell fate decisions. During the first decision, the trophectoderm and the inner cell mass are formed. Subsequently, the inner cell mass segregates into the epiblast and the primitive endoderm. Inner cell mass organoids represent an experimental model system, mimicking the second cell fate decision. It has been shown that cells of the same fate tend to cluster stronger than expected for random cell fate decisions. Three major processes are hypothesised to contribute to the cell fate arrangements: (1) chemical signalling; (2) cell sorting; and (3) cell proliferation. In order to quantify the influence of cell proliferation on the observed cell lineage type clustering, we developed an agent-based model accounting for mechanical cell–cell interaction, i.e. adhesion and repulsion, cell division, stochastic cell fate decision and cell fate heredity. The model supports the hypothesis that initial cell fate acquisition is a stochastically driven process, taking place in the early development of inner cell mass organoids. Further, we show that the observed neighbourhood structures can emerge solely due to cell fate heredity during cell division.

Ratio and number of inner cell mass and trophoblast cells of in vitro and in vivo produced porcine embryos

1995 ◽  
Vol 43 (1) ◽  
pp. 304 ◽  
Author(s):  
D. Rath ◽  
H. Niemann ◽  
T. Tao ◽  
M. Boerjan
Keyword(s):  
Inner Cell Mass ◽  
Cell Mass ◽  
Trophoblast Cells

The preimplantation pig embryo: cell number and allocation to trophectoderm and inner cell mass of the blastocyst in vivo and in vitro

Development ◽  
1988 ◽  
Vol 102 (4) ◽  
pp. 793-803 ◽  
Author(s):  
V.E. Papaioannou ◽  
K.M. Ebert
Keyword(s):  
Inner Cell Mass ◽  
Cell Mass ◽  
Staining Technique ◽  
Cell Number ◽  
Total Cell ◽  
Differential Staining ◽  
Morphological Development ◽  
Total Cell Number

Total cell number as well as differential cell numbers representing the inner cell mass (ICM) and trophectoderm were determined by a differential staining technique for preimplantation pig embryos recovered between 5 and 8 days after the onset of oestrus. Total cell number increased rapidly over this time span and significant effects were found between embryos of the same chronological age from different females. Inner cells could be detected in some but not all embryos of 12–16 cells. The proportion of inner cells was low in morulae but increased during differentiation of ICM and trophectoderm in early blastocysts. The proportion of ICM cells then decreased as blastocysts expanded and hatched. Some embryos were cultured in vitro and others were transferred to the oviducts of immature mice as a surrogate in vivo environment and assessed for morphology and cell number after several days. Although total cell number did not reach in vivo levels, morphological development and cell number increase was sustained better in the immature mice than in vitro. The proportion of ICM cells in blastocysts formed in vitro was in the normal range.

P–132 Centralized versus local embryologists scoring of blastocyst quality obtained in a large European multicenter clinical trial

2021 ◽  
Vol 36 (Supplement_1) ◽  
Author(s):  
M Montag ◽  
E Va. de. Abbeel ◽  
T Ebner ◽  
P Larsson ◽  
B Mannaerts
Keyword(s):  
Quality Assessment ◽  
Data Storage ◽  
Inner Cell Mass ◽  
Cell Mass ◽  
Time Lapse ◽  
Ongoing Pregnancy Rate ◽  
Quality Classification ◽  
Blastocyst Quality ◽  
Selection Of ◽  
Local Assessment

Abstract Study question Does blastocyst quality scoring by central assessment deviate from local assessment and potentially lead to the selection of a different single blastocyst for transfer? Summary answer Central and local assessment provided the same quality classification (poor / good / top) in 69% of all blastocysts and 63% of all transferred blastocysts. What is known already Blastocyst quality is scored most frequently by three morphological parameters, namely expansion and hatching (EH) status, inner cell mass (ICM) grading and trophectoderm (TE) grading. The score is used to define the quality classification (poor / good / top) which determines which embryo is to be transferred or cryopreserved. Blastocyst scoring and grading can be highly subjective, which does influence the choice for transfer and cryopreservation. Time-lapse imaging technology captures additional input about embryo development as well as enables centralized data storage and sharing for independent central assessments. Study design, size, duration Pooled embryo analysis from a prospective, randomized, multicenter trial (RAINBOW) of 619 women undergoing ovarian stimulation with an individualized dose of follitropin delta in a long GnRH agonist protocol between May 2018 and January 2020. Blastocysts were centrally assessed using time-lapse images by two independent assessors and one adjudicator . Selection of the blastocyst for transfer by local assessment was based on morphological scoring and not on morphokinetic time-lapse parameters. Participants/materials, setting, methods Oocytes were fertilized by ICSI and cultured in the Embryoscopeâ (Vitrolife) up to day 5 for transfer or day 5/6 for cryopreservation. Embryos were assessed as either non-blastocyst or blastocyst. Blastocysts were graded centrally and locally at 116 hrs of development, based on EH status (1–6), ICM (A-D) and TE grading (A-D). Central assessors were blinded to local assessment and embryo transfer selection. Main results and the role of chance In total 4282 embryos were assessed centrally, of which 2046 day 5 embryos (48%) were adjudicated due to a scoring difference of at least one parameter between the two central assessors. In total 38% of day 5 embryos were judged as non-blastocysts and 62% as blastocysts of which 61% (i.e. 38% of all embryos) were determined to be of good or top quality. Identical results in terms of quality classification (poor / good / top) were obtained for 69% of blastocysts between local and central assessment and in 78%, between the two central assessors. Moreover, central and local scoring were identical in 62% for EH status, 53% for ICM grading and 57% for TE grading. For all transferred blastocysts (n = 508), central and local quality assessment was aligned for 63%. The ongoing pregnancy rate following single blastocyst transfer (SBT) was 41% (202/489), and similar to when considering only the transfers for which the central assessment had the same or a higher classification than the local assessment (166/411=40%). In 16% of all SBT, central quality assessment gave a lower score for the transferred blastocyst than the central assessment. This discrepancy could potentially have led to transfer of a different blastocyst. Limitations, reasons for caution This trial included assessments made by embryologists from 20 IVF centres. Some centres has limited experience with time-lapse technology for morphological blastocyst scoring. Scoring could therefore have been affected by differences in focal planes, magnification and contrast compared to inverted microscopy, with potential influence on blastocyst scores and quality classification. Wider implications of the findings: Local and central blastocyst quality classification based on morphology aligns well but remains subjective. Embryo assessment may benefit from using tools like artificial intelligence-based algorithms for a more objective analysis. Trial registration number NCT03564509

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