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Nature Feb 2019Mammalian organogenesis is a remarkable process. Within a short timeframe, the cells of the three germ layers transform into an embryo that includes most of the major...
Mammalian organogenesis is a remarkable process. Within a short timeframe, the cells of the three germ layers transform into an embryo that includes most of the major internal and external organs. Here we investigate the transcriptional dynamics of mouse organogenesis at single-cell resolution. Using single-cell combinatorial indexing, we profiled the transcriptomes of around 2 million cells derived from 61 embryos staged between 9.5 and 13.5 days of gestation, in a single experiment. The resulting 'mouse organogenesis cell atlas' (MOCA) provides a global view of developmental processes during this critical window. We use Monocle 3 to identify hundreds of cell types and 56 trajectories, many of which are detected only because of the depth of cellular coverage, and collectively define thousands of corresponding marker genes. We explore the dynamics of gene expression within cell types and trajectories over time, including focused analyses of the apical ectodermal ridge, limb mesenchyme and skeletal muscle.
Topics: Animals; Ectoderm; Embryo, Mammalian; Female; Gene Expression Regulation, Developmental; Genetic Markers; Male; Mesoderm; Mice; Muscle Development; Muscle, Skeletal; Organ Specificity; Organogenesis; Sequence Analysis, RNA; Single-Cell Analysis; Time Factors; Transcriptome
PubMed: 30787437
DOI: 10.1038/s41586-019-0969-x -
Nature Nov 2021Understanding human organ formation is a scientific challenge with far-reaching medical implications. Three-dimensional stem-cell cultures have provided insights into...
Understanding human organ formation is a scientific challenge with far-reaching medical implications. Three-dimensional stem-cell cultures have provided insights into human cell differentiation. However, current approaches use scaffold-free stem-cell aggregates, which develop non-reproducible tissue shapes and variable cell-fate patterns. This limits their capacity to recapitulate organ formation. Here we present a chip-based culture system that enables self-organization of micropatterned stem cells into precise three-dimensional cell-fate patterns and organ shapes. We use this system to recreate neural tube folding from human stem cells in a dish. Upon neural induction, neural ectoderm folds into a millimetre-long neural tube covered with non-neural ectoderm. Folding occurs at 90% fidelity, and anatomically resembles the developing human neural tube. We find that neural and non-neural ectoderm are necessary and sufficient for folding morphogenesis. We identify two mechanisms drive folding: (1) apical contraction of neural ectoderm, and (2) basal adhesion mediated via extracellular matrix synthesis by non-neural ectoderm. Targeting these two mechanisms using drugs leads to morphological defects similar to neural tube defects. Finally, we show that neural tissue width determines neural tube shape, suggesting that morphology along the anterior-posterior axis depends on neural ectoderm geometry in addition to molecular gradients. Our approach provides a new route to the study of human organ morphogenesis in health and disease.
Topics: Ectoderm; Humans; Models, Biological; Morphogenesis; Neural Plate; Neural Tube; Neural Tube Defects; Organ Culture Techniques; Regeneration; Stem Cells
PubMed: 34707290
DOI: 10.1038/s41586-021-04026-9 -
Fertility and Sterility Mar 2014To determine the relationship between the age of the female partner and the prevalence and nature of human embryonic aneuploidy. (Review)
Review
The nature of aneuploidy with increasing age of the female partner: a review of 15,169 consecutive trophectoderm biopsies evaluated with comprehensive chromosomal screening.
OBJECTIVE
To determine the relationship between the age of the female partner and the prevalence and nature of human embryonic aneuploidy.
DESIGN
Retrospective.
SETTING
Academic.
PATIENT(S)
Trophectoderm biopsies.
INTERVENTION(S)
Comprehensive chromosomal screening performed on patients with blastocysts available for biopsy.
MAIN OUTCOME MEASURE(S)
Evaluation of the impact of maternal age on the prevalence of aneuploidy, the probability of having no euploid embryos within a cohort, the complexity of aneuploidy as gauged by the number of aneuploid chromosomes, and the trisomy/monosomy ratio.
RESULT(S)
Aneuploidy increased predictably after 26 years of age. A slightly increased prevalence was noted at younger ages, with >40% aneuploidy in women 23 years and under. The no euploid embryo rate was lowest (2% to 6%) in women aged 26 to 37, was 33% at age 42, and was 53% at age 44. Among the biopsies with aneuploidy, 64% involved a single chromosome, 20% two chromosomes, and 16% three chromosomes, with the proportion of more complex aneuploidy increasing with age. Finally, the trisomy/monosomy ratio approximated 1 and increased minimally with age.
CONCLUSION(S)
The lowest risk for embryonic aneuploidy was between ages 26 and 30. Both younger and older age groups had higher rates of aneuploidy and an increased risk for more complex aneuploidies. The overall risk did not measurably change after age 43. Trisomies and monosomies are equally prevalent.
Topics: Adult; Aneuploidy; Biopsy; Blastocyst; Cohort Studies; Ectoderm; Female; Genetic Testing; Humans; Maternal Age; Middle Aged; Retrospective Studies; Young Adult
PubMed: 24355045
DOI: 10.1016/j.fertnstert.2013.11.004 -
Wiley Interdisciplinary Reviews.... Sep 2017A mouth is present in all animals, and comprises an opening from the outside into the oral cavity and the beginnings of the digestive tract to allow eating. This review... (Review)
Review
A mouth is present in all animals, and comprises an opening from the outside into the oral cavity and the beginnings of the digestive tract to allow eating. This review focuses on the earliest steps in mouth formation. In the first half, we conclude that the mouth arose once during evolution. In all animals, the mouth forms from ectoderm and endoderm. A direct association of oral ectoderm and digestive endoderm is present even in triploblastic animals, and in chordates, this region is known as the extreme anterior domain (EAD). Further support for a single origin of the mouth is a conserved set of genes that form a 'mouth gene program' including foxA and otx2. In the second half of this review, we discuss steps involved in vertebrate mouth formation, using the frog Xenopus as a model. The vertebrate mouth derives from oral ectoderm from the anterior neural ridge, pharyngeal endoderm and cranial neural crest (NC). Vertebrates form a mouth by breaking through the body covering in a precise sequence including specification of EAD ectoderm and endoderm as well as NC, formation of a 'pre-mouth array,' basement membrane dissolution, stomodeum formation, and buccopharyngeal membrane perforation. In Xenopus, the EAD is also a craniofacial organizer that guides NC, while reciprocally, the NC signals to the EAD to elicit its morphogenesis into a pre-mouth array. Human mouth anomalies are prevalent and are affected by genetic and environmental factors, with understanding guided in part by use of animal models. WIREs Dev Biol 2017, 6:e275. doi: 10.1002/wdev.275 For further resources related to this article, please visit the WIREs website.
Topics: Animals; Ectoderm; Endoderm; Gene Expression Regulation, Developmental; Humans; Mouth; Neural Crest; Xenopus
PubMed: 28514120
DOI: 10.1002/wdev.275 -
Cell Stem Cell Sep 2017Directing the fate of human pluripotent stem cells (hPSCs) into different lineages requires variable starting conditions and components with undefined activities,...
Directing the fate of human pluripotent stem cells (hPSCs) into different lineages requires variable starting conditions and components with undefined activities, introducing inconsistencies that confound reproducibility and assessment of specific perturbations. Here we introduce a simple, modular protocol for deriving the four main ectodermal lineages from hPSCs. By precisely varying FGF, BMP, WNT, and TGFβ pathway activity in a minimal, chemically defined medium, we show parallel, robust, and reproducible derivation of neuroectoderm, neural crest (NC), cranial placode (CP), and non-neural ectoderm in multiple hPSC lines, on different substrates independently of cell density. We highlight the utility of this system by interrogating the role of TFAP2 transcription factors in ectodermal differentiation, revealing the importance of TFAP2A in NC and CP specification, and performing a small-molecule screen that identified compounds that further enhance CP differentiation. This platform provides a simple stage for systematic derivation of the entire range of ectodermal cell types.
Topics: Bone Morphogenetic Proteins; Cell Differentiation; Cell Lineage; Ectoderm; Gene Expression Regulation, Developmental; Humans; Neural Crest; Neural Plate; Neural Stem Cells; Phenanthrolines; Pluripotent Stem Cells; Signal Transduction; Small Molecule Libraries; Transcription Factor AP-2
PubMed: 28886367
DOI: 10.1016/j.stem.2017.08.015 -
American Journal of Physiology. Cell... Feb 2019Significant embryo loss remains a serious problem in pig production. Reactive oxygen species (ROS) play a critical role in embryonic implantation and placentation....
Significant embryo loss remains a serious problem in pig production. Reactive oxygen species (ROS) play a critical role in embryonic implantation and placentation. However, the potential mechanism of ROS on porcine trophectoderm (pTr) cell fate during the peri-implantation period has not been investigated. This study aimed to elucidate the effects of ROS on pTr cell phenotypes and the regulatory role in cell attachment and differentiation. Herein, results showed that exogenous HO inhibited pTr cell viability, arrested the cell cycle at S and G2/M phases, and increased cell apoptosis and autophagy protein light chain 3B and Beclin-1, whereas these effects were reversed by different concentrations of N-acetyl-l-cysteine (NAC) posttreatment. In addition, NAC abolished HO-induced autophagic flux, inhibited intracellular and mitochondrial ROS, and restored expression of genes important for mitochondrial DNA and biogenesis, cell attachment, and differentiation. NAC reversed HO-activated MAPK and Akt/mammalian target of rapamycin pathways in dose-dependent manners. Furthermore, analyses with pharmacological and RNA interference approaches suggested that autophagy regulated cell apoptosis and gene expression of caudal-related homeobox 2 and IL-1β. Collectively, these results provide new insights into the role of the ROS-induced autophagy in pTr cell apoptosis, attachment, and differentiation, indicating a promising target for decreasing porcine conceptus loss during the peri-implantation period.
Topics: Animals; Apoptosis; Autophagy; Cell Differentiation; Cell Proliferation; Cell Survival; Ectoderm; Hydrogen Peroxide; Reactive Oxygen Species; Swine; Trophoblasts
PubMed: 30485137
DOI: 10.1152/ajpcell.00256.2018 -
Current Topics in Developmental Biology 2015Cranial sensory placodes derive from discrete patches of the head ectoderm and give rise to numerous sensory structures. During gastrulation, a specialized "neural... (Review)
Review
Cranial sensory placodes derive from discrete patches of the head ectoderm and give rise to numerous sensory structures. During gastrulation, a specialized "neural border zone" forms around the neural plate in response to interactions between the neural and nonneural ectoderm and signals from adjacent mesodermal and/or endodermal tissues. This zone subsequently gives rise to two distinct precursor populations of the peripheral nervous system: the neural crest and the preplacodal ectoderm (PPE). The PPE is a common field from which all cranial sensory placodes arise (adenohypophyseal, olfactory, lens, trigeminal, epibranchial, otic). Members of the Six family of transcription factors are major regulators of PPE specification, in partnership with cofactor proteins such as Eya. Six gene activity also maintains tissue boundaries between the PPE, neural crest, and epidermis by repressing genes that specify the fates of those adjacent ectodermally derived domains. As the embryo acquires anterior-posterior identity, the PPE becomes transcriptionally regionalized, and it subsequently becomes subdivided into specific placodes with distinct developmental fates in response to signaling from adjacent tissues. Each placode is characterized by a unique transcriptional program that leads to the differentiation of highly specialized cells, such as neurosecretory cells, sensory receptor cells, chemosensory neurons, peripheral glia, and supporting cells. In this review, we summarize the transcriptional and signaling factors that regulate key steps of placode development, influence subsequent sensory neuron specification, and discuss what is known about mutations in some of the essential PPE genes that underlie human congenital syndromes.
Topics: Afferent Pathways; Ectoderm; Gene Expression Regulation, Developmental; Head; Humans; Models, Biological; Neural Plate; Signal Transduction
PubMed: 25662264
DOI: 10.1016/bs.ctdb.2014.11.009 -
Annual Review of Entomology 2014Oenocytes have intrigued insect physiologists since the nineteenth century. Many years of careful but mostly descriptive research on these cells highlights their diverse... (Review)
Review
Oenocytes have intrigued insect physiologists since the nineteenth century. Many years of careful but mostly descriptive research on these cells highlights their diverse sizes, numbers, and anatomical distributions across Insecta. Contemporary molecular genetic studies in Drosophila melanogaster and Tribolium castaneum support the hypothesis that oenocytes are of ectodermal origin. They also suggest that, in both short and long germ-band species, oenocytes are induced from a Spalt major/Engrailed ectodermal zone by MAPK signaling. Recent glimpses into some of the physiological functions of oenocytes indicate that they involve fatty acid and hydrocarbon metabolism. Genetic studies in D. melanogaster have shown that larval oenocytes synthesize very-long-chain fatty acids required for tracheal waterproofing and that adult oenocytes produce cuticular hydrocarbons required for desiccation resistance and pheromonal communication. Exciting areas of future research include the evolution of oenocytes and their cross talk with other tissues involved in lipid metabolism such as the fat body.
Topics: Animals; Drosophila melanogaster; Ectoderm; Embryo, Nonmammalian; Insecta; Larva; Tribolium
PubMed: 24397521
DOI: 10.1146/annurev-ento-011613-162056 -
Acta Biochimica Et Biophysica Sinica Jan 2018One of the most important events during vertebrate embryogenesis is the formation or specification of the three germ layers, endoderm, mesoderm, and ectoderm. After a... (Review)
Review
One of the most important events during vertebrate embryogenesis is the formation or specification of the three germ layers, endoderm, mesoderm, and ectoderm. After a series of rapid cleavages, embryos form the mesendoderm and ectoderm during late blastulation and early gastrulation. The mesendoderm then further differentiates into the mesoderm and endoderm. Nodal, a member of the transforming growth factor β (TGF-β) superfamily, plays a pivotal role in mesendoderm formation by regulating the expression of a number of critical transcription factors, including Mix-like, GATA, Sox, and Fox. Because the Nodal signal transduction pathway is well-characterized, increasing effort has been made to delineate the spatiotemporal modulation of Nodal signaling during embryonic development. In this review, we summarize the recent progress delineating molecular regulation of Nodal signal intensity and duration during mesendoderm formation.
Topics: Animals; Ectoderm; Endoderm; Gene Expression Regulation, Developmental; Mesoderm; Mice; Models, Genetic; Nodal Protein; Signal Transduction
PubMed: 29206913
DOI: 10.1093/abbs/gmx128 -
Wiley Interdisciplinary Reviews.... 2016The sensory organs of the vertebrate head originate from simple ectodermal structures known as cranial placodes. All cranial placodes derive from a common domain... (Review)
Review
The sensory organs of the vertebrate head originate from simple ectodermal structures known as cranial placodes. All cranial placodes derive from a common domain adjacent to the neural plate, the preplacodal region, which is induced at the border of neural and non-neural ectoderm during gastrulation. Induction and specification of the preplacodal region is regulated by the fibroblast growth factor, bone morphogenetic protein, WNT, and retinoic acid signaling pathways, and characterized by expression of the EYA and SIX family of transcriptional regulators. Once the preplacodal region is specified, different combinations of local signaling molecules and placode-specific transcription factors, including competence factors, promote the induction of individual cranial placodes along the neural axis of the head region. In this review, we summarize the steps of cranial placode development and discuss the roles of the main signaling molecules and transcription factors that regulate these steps during placode induction, specification, and development. For further resources related to this article, please visit the WIREs website.
Topics: Animals; Ectoderm; Gene Expression Regulation, Developmental; Humans; Skull; Transcriptional Activation; Wnt Signaling Pathway
PubMed: 26952139
DOI: 10.1002/wdev.226