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Developmental Dynamics : An Official... Jul 1995We describe a series of stages for development of the embryo of the zebrafish, Danio (Brachydanio) rerio. We define seven broad periods of embryogenesis--the zygote,...
We describe a series of stages for development of the embryo of the zebrafish, Danio (Brachydanio) rerio. We define seven broad periods of embryogenesis--the zygote, cleavage, blastula, gastrula, segmentation, pharyngula, and hatching periods. These divisions highlight the changing spectrum of major developmental processes that occur during the first 3 days after fertilization, and we review some of what is known about morphogenesis and other significant events that occur during each of the periods. Stages subdivide the periods. Stages are named, not numbered as in most other series, providing for flexibility and continued evolution of the staging series as we learn more about development in this species. The stages, and their names, are based on morphological features, generally readily identified by examination of the live embryo with the dissecting stereomicroscope. The descriptions also fully utilize the optical transparancy of the live embryo, which provides for visibility of even very deep structures when the embryo is examined with the compound microscope and Nomarski interference contrast illumination. Photomicrographs and composite camera lucida line drawings characterize the stages pictorially. Other figures chart the development of distinctive characters used as staging aid signposts.
Topics: Animals; Blastocyst; Cleavage Stage, Ovum; Embryo, Nonmammalian; Gastrula; Morphogenesis; Temperature; Time Factors; Zebrafish; Zygote
PubMed: 8589427
DOI: 10.1002/aja.1002030302 -
Cell Sep 2022In vitro cultured stem cells with distinct developmental capacities can contribute to embryonic or extraembryonic tissues after microinjection into pre-implantation...
In vitro cultured stem cells with distinct developmental capacities can contribute to embryonic or extraembryonic tissues after microinjection into pre-implantation mammalian embryos. However, whether cultured stem cells can independently give rise to entire gastrulating embryo-like structures with embryonic and extraembryonic compartments remains unknown. Here, we adapt a recently established platform for prolonged ex utero growth of natural embryos to generate mouse post-gastrulation synthetic whole embryo models (sEmbryos), with both embryonic and extraembryonic compartments, starting solely from naive ESCs. This was achieved by co-aggregating non-transduced ESCs, with naive ESCs transiently expressing Cdx2 or Gata4 to promote their priming toward trophectoderm and primitive endoderm lineages, respectively. sEmbryos adequately accomplish gastrulation, advance through key developmental milestones, and develop organ progenitors within complex extraembryonic compartments similar to E8.5 stage mouse embryos. Our findings highlight the plastic potential of naive pluripotent cells to self-organize and functionally reconstitute and model the entire mammalian embryo beyond gastrulation.
Topics: Animals; Cell Differentiation; Embryo, Mammalian; Embryonic Development; Embryonic Stem Cells; Endoderm; Gastrulation; Mammals; Mice
PubMed: 35988542
DOI: 10.1016/j.cell.2022.07.028 -
Developmental Biology Jun 2021Early human post-implantation development involves extensive growth combined with a series of complex morphogenetic events. The lack of precise spatial and temporal... (Review)
Review
Early human post-implantation development involves extensive growth combined with a series of complex morphogenetic events. The lack of precise spatial and temporal control over these processes leads to pregnancy loss. Given the ethical and technical limitations in studying the natural human embryo, alternative approaches are needed to investigate mechanisms underlying this critical stage of human development. Here, we present an overview of the different stem cells and stem cell-derived models which serve as useful, albeit imperfect, tools in understanding human embryogenesis. Current models include stem cells that represent each of the three earliest lineages: human embryonic stem cells corresponding to the epiblast, hypoblast-like stem cells and trophoblast stem cells. We also review the use of human embryonic stem cells to model complex aspects of epiblast morphogenesis and differentiation. Additionally, we propose that the combination of both embryonic and extra-embryonic stem cells to form three-dimensional embryo models will provide valuable insights into cell-cell chemical and mechanical interactions that are essential for natural embryogenesis.
Topics: Animals; Embryo, Mammalian; Embryoid Bodies; Embryonic Development; Embryonic Stem Cells; Germ Layers; Humans; Stem Cells; Trophoblasts
PubMed: 33333069
DOI: 10.1016/j.ydbio.2020.12.010 -
Cell Stem Cell Oct 2022Several in vitro models have been developed to recapitulate mouse embryogenesis solely from embryonic stem cells (ESCs). Despite mimicking many aspects of early...
Several in vitro models have been developed to recapitulate mouse embryogenesis solely from embryonic stem cells (ESCs). Despite mimicking many aspects of early development, they fail to capture the interactions between embryonic and extraembryonic tissues. To overcome this difficulty, we have developed a mouse ESC-based in vitro model that reconstitutes the pluripotent ESC lineage and the two extraembryonic lineages of the post-implantation embryo by transcription-factor-mediated induction. This unified model recapitulates developmental events from embryonic day 5.5 to 8.5, including gastrulation; formation of the anterior-posterior axis, brain, and a beating heart structure; and the development of extraembryonic tissues, including yolk sac and chorion. Comparing single-cell RNA sequencing from individual structures with time-matched natural embryos identified remarkably similar transcriptional programs across lineages but also showed when and where the model diverges from the natural program. Our findings demonstrate an extraordinary plasticity of ESCs to self-organize and generate a whole-embryo-like structure.
Topics: Animals; Embryo, Mammalian; Embryonic Development; Embryonic Stem Cells; Mice; Mouse Embryonic Stem Cells; Neurulation
PubMed: 36084657
DOI: 10.1016/j.stem.2022.08.013 -
Nature Oct 2023The ability to study human post-implantation development remains limited owing to ethical and technical challenges associated with intrauterine development after...
The ability to study human post-implantation development remains limited owing to ethical and technical challenges associated with intrauterine development after implantation. Embryo-like models with spatially organized morphogenesis and structure of all defining embryonic and extra-embryonic tissues of the post-implantation human conceptus (that is, the embryonic disc, the bilaminar disc, the yolk sac, the chorionic sac and the surrounding trophoblast layer) remain lacking. Mouse naive embryonic stem cells have recently been shown to give rise to embryonic and extra-embryonic stem cells capable of self-assembling into post-gastrulation structured stem-cell-based embryo models with spatially organized morphogenesis (called SEMs). Here we extend those findings to humans using only genetically unmodified human naive embryonic stem cells (cultured in human enhanced naive stem cell medium conditions). Such human fully integrated and complete SEMs recapitulate the organization of nearly all known lineages and compartments of post-implantation human embryos, including the epiblast, the hypoblast, the extra-embryonic mesoderm and the trophoblast layer surrounding the latter compartments. These human complete SEMs demonstrated developmental growth dynamics that resemble key hallmarks of post-implantation stage embryogenesis up to 13-14 days after fertilization (Carnegie stage 6a). These include embryonic disc and bilaminar disc formation, epiblast lumenogenesis, polarized amniogenesis, anterior-posterior symmetry breaking, primordial germ-cell specification, polarized yolk sac with visceral and parietal endoderm formation, extra-embryonic mesoderm expansion that defines a chorionic cavity and a connecting stalk, and a trophoblast-surrounding compartment demonstrating syncytium and lacunae formation. This SEM platform will probably enable the experimental investigation of previously inaccessible windows of human early post implantation up to peri-gastrulation development.
Topics: Humans; Embryo Implantation; Embryo, Mammalian; Embryonic Development; Fertilization; Gastrulation; Germ Layers; Human Embryonic Stem Cells; Trophoblasts; Yolk Sac; Giant Cells
PubMed: 37673118
DOI: 10.1038/s41586-023-06604-5 -
Nature Feb 2011Studies in embryonic development have guided successful efforts to direct the differentiation of human embryonic and induced pluripotent stem cells (PSCs) into specific...
Studies in embryonic development have guided successful efforts to direct the differentiation of human embryonic and induced pluripotent stem cells (PSCs) into specific organ cell types in vitro. For example, human PSCs have been differentiated into monolayer cultures of liver hepatocytes and pancreatic endocrine cells that have therapeutic efficacy in animal models of liver disease and diabetes, respectively. However, the generation of complex three-dimensional organ tissues in vitro remains a major challenge for translational studies. Here we establish a robust and efficient process to direct the differentiation of human PSCs into intestinal tissue in vitro using a temporal series of growth factor manipulations to mimic embryonic intestinal development. This involved activin-induced definitive endoderm formation, FGF/Wnt-induced posterior endoderm pattering, hindgut specification and morphogenesis, and a pro-intestinal culture system to promote intestinal growth, morphogenesis and cytodifferentiation. The resulting three-dimensional intestinal 'organoids' consisted of a polarized, columnar epithelium that was patterned into villus-like structures and crypt-like proliferative zones that expressed intestinal stem cell markers. The epithelium contained functional enterocytes, as well as goblet, Paneth and enteroendocrine cells. Using this culture system as a model to study human intestinal development, we identified that the combined activity of WNT3A and FGF4 is required for hindgut specification whereas FGF4 alone is sufficient to promote hindgut morphogenesis. Our data indicate that human intestinal stem cells form de novo during development. We also determined that NEUROG3, a pro-endocrine transcription factor that is mutated in enteric anendocrinosis, is both necessary and sufficient for human enteroendocrine cell development in vitro. PSC-derived human intestinal tissue should allow for unprecedented studies of human intestinal development and disease.
Topics: Activins; Basic Helix-Loop-Helix Transcription Factors; Body Patterning; Cell Culture Techniques; Cell Differentiation; Cells, Cultured; Culture Media; Embryonic Stem Cells; Endoderm; Fibroblast Growth Factor 4; Humans; Induced Pluripotent Stem Cells; Intercellular Signaling Peptides and Proteins; Intestines; Microvilli; Morphogenesis; Nerve Tissue Proteins; Organogenesis; Time Factors; Wnt Proteins; Wnt3 Protein; Wnt3A Protein
PubMed: 21151107
DOI: 10.1038/nature09691 -
Nature Oct 2017Mouse embryonic stem cells derived from the epiblast contribute to the somatic lineages and the germline but are excluded from the extra-embryonic tissues that are...
Mouse embryonic stem cells derived from the epiblast contribute to the somatic lineages and the germline but are excluded from the extra-embryonic tissues that are derived from the trophectoderm and the primitive endoderm upon reintroduction to the blastocyst. Here we report that cultures of expanded potential stem cells can be established from individual eight-cell blastomeres, and by direct conversion of mouse embryonic stem cells and induced pluripotent stem cells. Remarkably, a single expanded potential stem cell can contribute both to the embryo proper and to the trophectoderm lineages in a chimaera assay. Bona fide trophoblast stem cell lines and extra-embryonic endoderm stem cells can be directly derived from expanded potential stem cells in vitro. Molecular analyses of the epigenome and single-cell transcriptome reveal enrichment for blastomere-specific signature and a dynamic DNA methylome in expanded potential stem cells. The generation of mouse expanded potential stem cells highlights the feasibility of establishing expanded potential stem cells for other mammalian species.
Topics: Animals; Blastocyst; Blastomeres; Cell Lineage; Cells, Cultured; Chimera; Embryo, Mammalian; Endoderm; Epigenesis, Genetic; Epigenomics; Female; Male; Mice; Mouse Embryonic Stem Cells; Placenta; Pluripotent Stem Cells; Pregnancy; Single-Cell Analysis; Transcriptome; Trophoblasts
PubMed: 29019987
DOI: 10.1038/nature24052 -
Cell Stem Cell May 2023Understanding the mechanisms of blastocyst formation and implantation is critical for improving farm animal reproduction but is hampered by a limited supply of embryos....
Understanding the mechanisms of blastocyst formation and implantation is critical for improving farm animal reproduction but is hampered by a limited supply of embryos. Here, we developed an efficient method to generate bovine blastocyst-like structures (termed blastoids) via assembling bovine trophoblast stem cells and expanded potential stem cells. Bovine blastoids resemble blastocysts in morphology, cell composition, single-cell transcriptomes, in vitro growth, and the ability to elicit maternal recognition of pregnancy following transfer to recipient cows. Bovine blastoids represent an accessible in vitro model for studying embryogenesis and improving reproductive efficiency in livestock species.
Topics: Pregnancy; Female; Cattle; Animals; Blastocyst; Trophoblasts; Embryo Implantation; Embryonic Development; Stem Cells; Cell Culture Techniques
PubMed: 37146582
DOI: 10.1016/j.stem.2023.04.003 -
Science (New York, N.Y.) Apr 2017Mammalian embryogenesis requires intricate interactions between embryonic and extraembryonic tissues to orchestrate and coordinate morphogenesis with changes in...
Mammalian embryogenesis requires intricate interactions between embryonic and extraembryonic tissues to orchestrate and coordinate morphogenesis with changes in developmental potential. Here, we combined mouse embryonic stem cells (ESCs) and extraembryonic trophoblast stem cells (TSCs) in a three-dimensional scaffold to generate structures whose morphogenesis is markedly similar to that of natural embryos. By using genetically modified stem cells and specific inhibitors, we show that embryogenesis of ESC- and TSC-derived embryos-ETS-embryos-depends on cross-talk involving Nodal signaling. When ETS-embryos develop, they spontaneously initiate expression of mesoderm and primordial germ cell markers asymmetrically on the embryonic and extraembryonic border, in response to Wnt and BMP signaling. Our study demonstrates the ability of distinct stem cell types to self-assemble in vitro to generate embryos whose morphogenesis, architecture, and constituent cell types resemble those of natural embryos.
Topics: Animals; Embryo Implantation; Embryo, Mammalian; Embryonic Development; Embryonic Stem Cells; Gastrulation; Germ Layers; In Vitro Techniques; Mesoderm; Mice; Models, Biological; Tissue Scaffolds; Trophoblasts; Wnt Signaling Pathway
PubMed: 28254784
DOI: 10.1126/science.aal1810 -
Cell Stem Cell Jun 2023Gastruloids are 3D structures generated from pluripotent stem cells recapitulating fundamental principles of embryonic pattern formation. Using single-cell genomic...
Gastruloids are 3D structures generated from pluripotent stem cells recapitulating fundamental principles of embryonic pattern formation. Using single-cell genomic analysis, we provide a resource mapping cell states and types during gastruloid development and compare them with the in vivo embryo. We developed a high-throughput handling and imaging pipeline to spatially monitor symmetry breaking during gastruloid development and report an early spatial variability in pluripotency determining a binary response to Wnt activation. Although cells in the gastruloid-core revert to pluripotency, peripheral cells become primitive streak-like. These two populations subsequently break radial symmetry and initiate axial elongation. By performing a compound screen, perturbing thousands of gastruloids, we derive a phenotypic landscape and infer networks of genetic interactions. Finally, using a dual Wnt modulation, we improve the formation of anterior structures in the existing gastruloid model. This work provides a resource to understand how gastruloids develop and generate complex patterns in vitro.
Topics: Mice; Animals; Embryo, Mammalian; Primitive Streak; Pluripotent Stem Cells; Embryonic Development
PubMed: 37209681
DOI: 10.1016/j.stem.2023.04.018