Neuroectodermal fate of epiblast cells in the distal region of the mouse egg cylinder: implication for body plan organization during early embryogenesis

Development ◽  
1995 ◽  
Vol 121 (1) ◽  
pp. 87-98 ◽  
Author(s):  
G.A. Quinlan ◽  
E.A. Williams ◽  
S.S. Tan ◽  
P.P. Tam
Keyword(s):  
Cell Fate ◽  
Neural Tube ◽  
Primitive Streak ◽  
Distal Region ◽  
Small Population ◽  
Surface Ectoderm ◽  
Minor Contribution ◽  
Stage Embryo ◽  
A Minor

The developmental fate of cells in the distal region (distal cap) of the epiblast was analysed by fate mapping studies. The displacement and differentiation of cells labelled in situ with carbocyanine dyes and lacZ-expressing cells grafted to the distal cap were studied over a 48-hour period of in vitro development. The distal cap epiblast differentiates predominantly into neurectodermal cells. Cells at the anterior site of the distal cap colonise the fore-, mid- and hindbrain and contribute to non-neural ectoderm cells of the amnion and craniofacial surface ectoderm. Those cells in the most distal region of the epiblast contribute to all three brain compartments as well as the spinal cord and the posterior neuropore. Cells at the posterior site of the distal cap are mainly localised to the caudal parts of the neural tube. A minor contribution to the embryonic (paraxial and lateral) and extraembryonic (allantoic and yolk sac) mesoderm is also found. Epiblast cells located outside the distal cap give rise to surface ectoderm and other non-ectodermal derivatives, with only a minor contribution to the neuroectoderm. Results of this study provide compelling evidence that the precursor population of the neural tube is contained in the distal cap epiblast of the early-primitive-streak-stage embryo. Furthermore, the regionalisation of cell fate within this small population suggest that a preliminary craniocaudal patterning may have occurred in the neural primordium before neurulation.

scholarly journals Prediction and control of symmetry breaking in embryoid bodies by environment and signal integration

2018 ◽  
Author(s):  
Naor Sagy ◽  
Shaked Slovin ◽  
Maya Allalouf ◽  
Maayan Pour ◽  
Gaya Savyon ◽  
...  
Keyword(s):  
Symmetry Breaking ◽  
Cell Fate ◽  
Developmental Process ◽  
Primitive Streak ◽  
Early Embryo ◽  
Embryoid Bodies ◽  
Neighboring Cell ◽  
Contact Points

AbstractDuring early embryogenesis, mechanical signals, localized biochemical signals and neighboring cell layers interaction coordinate around anteroposterior axis determination and symmetry breaking. Deciphering their relative roles, which are hard to tease apart in vivo, will enhance our understanding of how these processes are driven. In recent years, in vitro 3D models of early mammalian development, such as embryoid bodies (EBs) and gastruloids, were successful in mimicking various aspects of the early embryo, providing high throughput accessible systems for studying the basic rules shaping cell fate and morphology during embryogenesis. Using Brachyury (Bry), a primitive streak and mesendoderm marker in EBs, we study how contact, biochemical and neighboring cell cues affect the positioning of a primitive streak-like locus, determining the AP axis. We show that a Bry-competent layer must be formed in the EB before Bry expression initiates, and that Bry onset locus selection depends on contact points of the EB with its surrounding. We can maneuver Bry onset to occur at a specific locus, a few loci, or in an isotropic peripheral pattern. By spatially separating contact and biochemical signal sources, we show these two modalities can be integrated by the EB to generate a single Bry locus. Finally, we show Foxa2+ cells are predictive of the future location of Bry onset, demonstrating an earlier symmetry-breaking event. By delineating the temporal signaling pathway dependencies of Bry and Foxa2, we were able to selectively abolish either, or spatially decouple the two cell types during EB differentiation. These findings demonstrate multiple inputs integration during an early developmental process, and may prove valuable in directing in vitro differentiation.

scholarly journals The RNA helicase DDX6 controls early mouse embryogenesis by repressing aberrant inhibition of BMP signaling through miRNA-mediated gene silencing

2021 ◽  
Author(s):  
Jessica Kim ◽  
Masafumi Muraoka ◽  
Rieko Ajima ◽  
Hajime Okada ◽  
Atsushi Toyoda ◽  
...  
Keyword(s):  
Cell Fate ◽  
Primitive Streak ◽  
Rna Helicase ◽  
Bmp Signaling ◽  
Negative Regulators ◽  
Pluripotent Cells ◽  
Mouse Embryogenesis ◽  
Neural Lineage ◽  
Early Mouse

The evolutionarily conserved RNA helicase DDX6 is a central player of post-transcriptional regulation, but its role during embryogenesis remains elusive. We here demonstrated that DDX6 enables proper cell lineage specification from pluripotent cells by analyzing Ddx6 KO mouse embryos and in vitro epiblast-like cell (EpiLC) induction system. Our study unveiled a great impact of DDX6-mediated RNA regulation on signaling pathways. Deletion of Ddx6 caused the aberrant transcriptional upregulation of the negative regulators of BMP signaling, which accompanied with enhanced Nodal signaling. Ddx6 / pluripotent cells acquired higher pluripotency with a strong inclination toward neural lineage commitment. During gastrulation, abnormally expanded Nodal expression in the primitive streak likely promoted endoderm cell fate specification while inhibiting mesoderm development. We further clarified the mechanism how DDX6 regulates cell fate determination of pluripotent cells by genetically dissecting major DDX6 pathways: processing body (P-body) formation, translational repression, mRNA decay, and miRNA-mediated silencing. P-body-related functions were dispensable, but the miRNA pathway was essential for the DDX6 function. DDX6 may prevent aberrant transcriptional upregulation of the negative regulators of BMP signaling by repressing translation of certain transcription factors through the interaction with miRNA-induced silencing complexes (miRISCs). Overall, this delineates how DDX6 affects development of the three primary germ layers during early mouse embryogenesis and the underlying mechanism of DDX6 function.

Cell fate, morphogenetic movement and population kinetics of embryonic endoderm at the time of germ layer formation in the mouse

Development ◽  
1987 ◽  
Vol 101 (3) ◽  
pp. 627-652 ◽  
Author(s):  
K.A. Lawson ◽  
R.A. Pedersen
Keyword(s):  
Cell Fate ◽  
Doubling Time ◽  
Primitive Streak ◽  
Yolk Sac ◽  
Population Doubling ◽  
Population Doubling Time ◽  
Germ Layer ◽  
Posterior Half ◽  
Visceral Yolk Sac

The fate of the embryonic endoderm (generally called visceral embryonic endoderm) of prestreak and early primitive streak stages of the mouse embryo was studied in vitro by microinjecting horseradish peroxidase into single axial endoderm cells of 6.7-day-old embryos and tracing the labelled descendants either through gastrulation (1 day of culture) or to early somite stages (2 days of culture). Descendants of endoderm cells from the anterior half of the axis were found at the extreme cranial end of the embryo after 1 day and in the visceral yolk sac endoderm after 2 days, i.e. they were displaced anteriorly and anterolaterally. Descendants of cells originating over and near the anterior end of the early primitive streak, i.e. posterior to the distal tip of the egg cylinder, were found after 1 day over the entire embryonic axis and after 2 days in the embryonic endoderm at the anterior intestinal portal, in the foregut, along the trunk and postnodally, as well as anteriorly and posteriorly in the visceral yolk sac. Endoderm covering the posterior half of the early primitive streak contributed to postnodal endoderm after 1 day (at the late streak stage) and mainly to posterior visceral yolk sac endoderm after 2 days. Clonal descendants of axial endoderm were located after 2 days either over the embryo or in the yolk sac; the few exceptions spanned the caudal end of the embryo and the posterior yolk sac. The clonal analysis also showed that the endoderm layer along the posterior half of the axis of prestreak- and early-streak-stage embryos is heterogeneous in its germ layer fate. Whereas the germ layer location of descendants from anterior sites did not differ after 1 day from that expected from the initial controls (approx. 90% exclusively in endoderm), only 62% of the successfully injected posterior sites resulted in labelled cells exclusively in endoderm; the remainder contributed partially or entirely to ectoderm and mesoderm. This loss from the endoderm layer was compensated by posterior-derived cells that remained in endoderm having more surviving descendants (8.4 h population doubling time) than did anterior-derived cells (10.5 h population doubling time). There was no indication of cell death at the prestreak and early streak stages; at least 93% of the cells were proliferating and more than half of the total axial population were in, or had completed, a third cell cycle after 22 h culture.(ABSTRACT TRUNCATED AT 400 WORDS)

Regionalisation of the mouse embryonic ectoderm: allocation of prospective ectodermal tissues during gastrulation

Development ◽  
1989 ◽  
Vol 107 (1) ◽  
pp. 55-67 ◽  
Author(s):  
P.P. Tam
Keyword(s):  
Spinal Cord ◽  
Cell Fate ◽  
Primitive Streak ◽  
Surface Ectoderm ◽  
Lateral Region ◽  
Anterior Midline ◽  
Cranial Neural Crest Cells ◽  
Lateral Mesoderm ◽  
Somitic Mesoderm ◽  
Embryonic Ectoderm

The regionalisation of cell fate in the embryonic ectoderm was studied by analyzing the distribution of graft-derived cells in the chimaeric embryo following grafting of wheat germ agglutinin—gold-labelled cells and culturing primitive-streak-stage mouse embryos. Embryonic ectoderm in the anterior region of the egg cylinder contributes to the neuroectoderm of the prosencephalon and mesencephalon. Cells in the distal lateral region give rise to the neuroectoderm of the rhombencephalon and the spinal cord. Embryonic ectoderm at the archenteron and adjacent to the middle region of the primitive streak contributes to the neuroepithelium of the spinal cord. The proximal-lateral ectoderm and the ectodermal cells adjacent to the posterior region of the primitive streak produce the surface ectoderm, the epidermal placodes and the cranial neural crest cells. Some labelled cells grafted to the anterior midline are found in the oral ectodermal lining, whereas cells from the archenteron are found in the notochord. With respect to mesodermal tissues, ectoderm at the archenteron and the distal-lateral region of the egg cylinder gives rise to rhombencephalic somitomeres, and the embryonic ectoderm adjacent to the primitive streak contributes to the somitic mesoderm and the lateral mesoderm. Based upon results of this and other grafting studies, a map of prospective ectodermal tissues in the embryonic ectoderm of the full-streak-stage mouse embryo is constructed.

scholarly journals The TAF10-containing TFIID and SAGA transcriptional complexes are dispensable for early somitogenesis in the mouse embryo

2016 ◽  
Author(s):  
Paul Bardot ◽  
Stéphane D. Vincent ◽  
Marjorie Fournier ◽  
Alexis Hubaud ◽  
Mathilde Joint ◽  
...  
Keyword(s):  
Cell Fate ◽  
Mouse Embryo ◽  
Control Cell ◽  
Paraxial Mesoderm ◽  
Mrna Levels ◽  
Lateral Plate ◽  
Mesoderm Development ◽  
Regulated Gene Expression ◽  
A Minor

AbstractDuring development, tightly regulated gene expression programs control cell fate and patterning. A key regulatory step in eukaryotic transcription is the assembly of the pre-initiation complex (PIC) at promoters. The PIC assembly has mainly been studiedin vitro, and little is known about its composition during development.In vitrodata suggests that TFIID is the general transcription factor that nucleates PIC formation at promoters. Here we show that TAF10, a subunit of TFIID and of the transcriptional co-activator SAGA, is required for the assembly of these complexes in the mouse embryo. We performedTaf10conditional deletions during mesoderm development and show thatTaf10loss in the presomitic mesoderm (PSM) does not prevent cyclic gene transcription or PSM segmental patterning, while lateral plate differentiation is profoundly altered. During this period, global mRNA levels are unchanged in the PSM, with only a minor subset of genes dysregulated. Together, our data demonstrate that the TAF10-containing canonical TFIID and SAGA complexes, are dispensable for early paraxial mesoderm development, arguing against the generic role in transcription proposed for these fully assembled holo complexes.

scholarly journals Reconstruction of dynamic regulatory networks reveals signaling-induced topology changes associated with germ layer specification

2021 ◽  
Author(s):  
Emily Y Su ◽  
Abby Spangler ◽  
Qin Bian ◽  
Jessica Y Kasamoto ◽  
Patrick Cahan
Keyword(s):  
Signaling Pathways ◽  
Cell Fate ◽  
Regulatory Networks ◽  
Target Genes ◽  
Dynamic Networks ◽  
Dynamic Network ◽  
Primitive Streak ◽  
Reconstruction Methods

Elucidating regulatory relationships between transcription factors (TFs) and target genes is fundamental to understanding how cells control their identity and behavior. Computational gene regulatory network (GRN) reconstruction methods aim to map this control by inferring relationships from transcriptomic data. Unfortunately, existing methods are imprecise, may be computationally burdensome, and do not illustrate how networks transition from one topology to another. Here we present Epoch, a computational network reconstruction tool that leverages single cell transcriptomics to infer dynamic network structures. Epoch performs favorably when benchmarked on reconstruction of synthetically generated, in vivo, and in vitro data. To illustrate the usefulness of Epoch, we used it to identify the dynamic networks underpinning directed differentiation of mouse ESC guided by multiple primitive streak induction treatments. Our analysis demonstrates that modulating signaling pathways drives topological network changes that shape cell fate potential. We also find that Peg3 is a central contributor to the rewiring of the pluripotency network to favor mesoderm specification. By integrating signaling pathways with GRN structures, we traced how Wnt activation and PI3K suppression govern mesoderm and endoderm specification, respectively. The methods presented here are available in the R package Epoch, and provide a foundation for future work in understanding the biological implications of dynamic regulatory structures.

scholarly journals Self-organized morphogenesis of a human neural tube in vitro by geometric constraints

2021 ◽  
Author(s):  
Eyal Karzbrun ◽  
Aimal Khankhel ◽  
Heitor Megale ◽  
Stella Glasauer ◽  
Yofiel Wyle ◽  
...  
Keyword(s):  
Stem Cell ◽  
Pattern Formation ◽  
Cell Fate ◽  
Neural Tube ◽  
Cell Sheet ◽  
Tissue Mechanics ◽  
Geometric Constraints ◽  
Human Embryos ◽  
Human Organ

Understanding how human embryos develop their shape is a fundamental question in physics of life with strong medical implications. However, it is not possible to study the dynamics of organ formation in humans. Animals differ from humans in key aspects, and in particular in the development of the nervous system. Conventional organoids are unreproducible and do not recapitulate the intricate anatomy of organs. Here we present a reproducible and scalable approach for studying human organogenesis in a dish, which is compatible with live imaging. We achieve this by precisely controlling cell fate pattern formation in 2D stem cell sheets, while allowing for self-organization of tissue shape in 3D. Upon triggering neural pattern formation, the initially flat stem cell sheet undergoes folding morphogenesis and self-organizes into a millimeter long anatomically true neural tube covered by epidermis. In contrast to animal studies, neural and epidermal human tissues are necessary and sufficient for folding morphogenesis in the absence of mesoderm activity. Furthermore, we model neural tube defects by interfering with signaling that regulates tissue mechanics. Finally, we discover that neural tube shape, including the number and location of hinge points, depends on neural tissue size. This suggests that neural tube morphology along the anterior posterior axis depends on neural plate geometry in addition to molecular gradients. Our approach provides the first path to study human organ morphogenesis in health and disease.

Growth of opossum embryos in vitro during organogenesis

Development ◽  
1977 ◽  
Vol 41 (1) ◽  
pp. 111-123
Author(s):  
D. A. T. New ◽  
M. Mizell ◽  
D. L. Cockroft
Keyword(s):  
Neural Tube ◽  
Blood Circulation ◽  
Primitive Streak ◽  
Yolk Sac ◽  
Body Movements

Opossum embryos, explanted between primitive streak and late fetal stages, were grown in culture for periods of 20–30 h. Many of the explants had a good heartbeat and blood circulation in embryo and yolk sac after 12 h, and a few after 24 h. Growth of the embryos included formation of the neural tube and body flexures, increase in the number of somites, differentiation of the limbs and digits, and development of the amnion and allantois. Embryos explanted during the last day of gestation showed persistent and vigorous body movements in culture, particularly of the forelimbs, head and tongue.

Chimaerism of primordial germ cells in the early postimplantation mouse embryo following microsurgical grafting of posterior primitive streak cells in vitro

Development ◽  
1986 ◽  
Vol 95 (1) ◽  
pp. 95-115
Author(s):  
Andrew J. Copp ◽  
Heather M. Roberts ◽  
Paul E. Polani
Keyword(s):  
Mouse Embryo ◽  
Primordial Germ Cells ◽  
Primordial Germ Cell ◽  
Experimental System ◽  
Primitive Streak ◽  
Mouse Embryos ◽  
Culture Methods ◽  
Surface Ectoderm ◽  
Intact Mouse

A microsurgical grafting technique has been used to introduce primordial germ cell (PGC) precursors into intact primitive-streak-stage mouse embryos in vitro. Operated embryos were cultured for 36–40 h and then analysed by a combined histochemical and autoradiographic method. PGC chimaerism occurred in embryos that received grafts of caudal primitive streak cells but not adjacent embryonic endoderm or anterolateral ectoderm/mesoderm cells. Graftderived PGCs were found to be migrating through the gut endoderm alongside host-derived PGCs in approximately half of the chimaeric embryos whereas in the other 50% of cases PGCs remained at the site of grafting in association with graft-derived somatic cells. A similar pattern of somatic chimaerism was produced by primitive streak and anterolateral ectoderm/mesoderm grafts: the allantois was colonized predominantly, with, in addition, formation of amnion, surface ectoderm and caudal mesoderm in a few embryos. The majority of embryonic endoderm grafts failed to incorporate into host embryos and formed yolk-sac-like vesicles. The findings of this study indicate that (a) PGCs originate from the embryonic ectoderm via the primitive streak during development of the mouse embryo, and (b) anterolateral ectoderm and mesoderm cells are unable to form PGCs after heterotopic grafting to the posterior primitive streak site. The combined microsurgical and embryo culture methods provide an experimental system for the analysis of PGC development in intact mouse embryos.

scholarly journals Quantitative analysis of signaling responses during mouse primordial germ cell specification

Biology Open ◽  
2021 ◽  
Vol 10 (5) ◽  
Author(s):  
Sophie M. Morgani ◽  
Anna-Katerina Hadjantonakis
Keyword(s):  
Cell Fate ◽  
Primordial Germ Cells ◽  
Primordial Germ Cell ◽  
Small Population ◽  
Bmp Signaling ◽  
Pluripotent Cells ◽  
Cell Fate Decisions ◽  
Germ Cell Specification

ABSTRACT During early mammalian development, the pluripotent cells of the embryo are exposed to a combination of signals that drive exit from pluripotency and germ layer differentiation. At the same time, a small population of pluripotent cells give rise to the primordial germ cells (PGCs), the precursors of the sperm and egg, which pass on heritable genetic information to the next generation. Despite the importance of PGCs, it remains unclear how they are first segregated from the soma, and if this involves distinct responses to their signaling environment. To investigate this question, we mapped BMP, MAPK and WNT signaling responses over time in PGCs and their surrounding niche in vitro and in vivo at single-cell resolution. We showed that, in the mouse embryo, early PGCs exhibit lower BMP and MAPK responses compared to neighboring extraembryonic mesoderm cells, suggesting the emergence of distinct signaling regulatory mechanisms in the germline versus soma. In contrast, PGCs and somatic cells responded comparably to WNT, indicating that this signal alone is not sufficient to promote somatic differentiation. Finally, we investigated the requirement of a BMP response for these cell fate decisions. We found that cell lines with a mutation in the BMP receptor (Bmpr1a−/−), which exhibit an impaired BMP signaling response, can efficiently generate PGC-like cells revealing that canonical BMP signaling is not cell autonomously required to direct PGC-like differentiation.

Sign in / Sign up

Export Citation Format

Share Document