Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Germ Layers”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 55 records · Page 3Linked to original sources
PubMed2025

Glycolytic activity instructs germ layer proportions through regulation of Nodal and Wnt signaling.

Metabolic pathways can influence cell fate decisions, yet their regulative role during embryonic development remains poorly understood. Here, we demonstrate an instructive role of glycolytic activity in regulating signaling pathways involved in mesoderm and endoderm specification. Using a mouse embryonic stem cell (mESC)-based in vitro model for gastrulation, we found that glycolysis inhibition increases ectodermal cell fates at the expense of mesodermal and endodermal lineages. We demonstrate that this relationship is dose dependent, enabling metabolic control of germ layer proportions through exogenous glucose levels. We further show that glycolysis acts as an upstream regulator of Nodal and Wnt signaling and that its influence on cell fate specification can be decoupled from its effects on growth. Finally, we confirm the generality of our findings using a human gastrulation model. Our work underscores the dependence of signaling pathways on metabolic conditions and provides mechanistic insight into the nutritional regulation of cell fate decision-making.

Glycolysis↗
PubMed1998

The role of maternal VegT in establishing the primary germ layers in Xenopus embryos.

VegT is a T-box transcription factor whose mRNA is synthesized during oogenesis and localized in the vegetal hemisphere of the egg and early embryo. We show that maternally expressed VegT controls the pattern of primary germ layer specification in Xenopus embryos. Reduction of the maternal store completely alters the fates of different regions of the blastula so that animal cell fate is changed from epidermis and nervous system to epidermis only, equatorial cell fate is changed from mesoderm to ectoderm, and vegetal cell fate is changed from endoderm to mesoderm and ectoderm. Vegetal cells lose their capacity both to form endoderm and to release mesoderm-inducing signals. These results show that a single maternally expressed gene controls the patterning of the Xenopus blastula.

Animals↗
PubMedDate not supplied

[Diffuse and compact chromatin in the cell nuclei from tissues derived from different germ layers].

Chromatin structure of nuclei of histogenetically distinct cells of humans and animals under normal and pathological courses of gestation was studied by the method of optic-structural computer analysis. A constant ratio of compact and diffuse chromatin is detected in nuclei of cells originating from all the germ layers. This ratio can change to a variable degree in cases of pathological gestation.

Animals↗
PubMed1991

The snail gene required for mesoderm formation in Drosophila is expressed dynamically in derivatives of all three germ layers.

The zygotic effect gene snail (sna) encodes a zinc-finger protein required for mesoderm formation in Drosophila embryos. By in situ analysis, sna transcripts are first detected at syncytial blastoderm and persist until very late stages of embryogenesis. Expression of sna is transient and is observed in tissues derived from all three germ layers. Prior to germband elongation, sna RNA accumulation is consistent with its genetically determined role in mesoderm formation. Starting at germband elongation, a second phase of sna expression appears to be initiated, characterized by a highly dynamic accumulation of transcripts in the developing central and peripheral nervous systems. Translation of sna RNA is apparently delayed as the sna protein is not detected before the onset of gastrulation. Its regional distribution generally correlates with that of sna transcripts. The complex pattern of sna expression strongly suggests that the function of the gene is not restricted to mesoderm formation.

Animals↗
PubMed2006

Somatic H1 histone accumulation and germ layer determination in amphibian embryos.

The induction of mesoderm and/or endoderm from prospective ectoderm and dorsalization of the marginal zone mesoderm may be linked to inhibition of cell cycling and DNA synthesis in early amphibian embryos. In turn, this may lead to reduction of somatic H1 histone accumulation. A greater number of cell cycles and rounds of DNA synthesis characterizes the induction of neural tissue. This is correlated with an increase of somatic H1 histone accumulation. The number of rounds of DNA replication may regulate the level of H1 histone accumulation and this may have a role in germ layer determination.

Amphibians↗
PubMed1979

Fine structural differentiation of germ layers in the mouse at the time of mesoderm formation.

The morphology of early postimplantation mouse egg cylinders was studied using light and electron microscopy. Implantation sites at seven, seven and one-half and eight days of gestation were dissected from the myometrium and whole implants, including both decidua and egg cylinders were processed for electron microscopy. Pre-primitive streak egg cylinders were composed of two germ layers, a tall columnar ectoderm and an outer visceral endodermal layer. Ectodermal cells demonstrated large oval nuclei and an organelle sparse cytoplasm except for many free polyribosomes. The visceral endodermal layer was composed of two cell populations. One visceral endodermal cell type observed was tall columnar in shape and appeared absorptive as demonstrated by many microvilli, pinocytotic profiles and lysosomal granules. This population was confined to extraembryonic regions of the egg cylinder. The second visceral endodermal cell type, squamous in shape, evidenced only a few microvilli, pinocytotic profiles and lysosomal granules. This population was confined to the embryonic region of the egg cylinder. Concurrent with the formation of the primitive streak an increased number of cellular junctions and nuclear pores became evident in the ectoderm. Mesodermal cells were large and stellate-shaped exhibiting many filapodia which made contact with adjacent mesodermal elements. Later the cephalic region of the primitive streak proliferated resulting in the migration of wedge-shaped mass of cells, the head process. At the most ventral extremity of the post-primitive streak egg cylinder the cells of the head process became intimately associated with the ectoderm by areas of focal contact and gap junctions.

Animals↗
PubMed2004

Establishment and characterization of a pluripotent stem cell line derived from human amniotic membranes and initiation of germ layers in vitro.

OBJECTIVES: Pluripotent stem cells are proposed to be used in regenerative therapy and may exist in the human amniotic membrane. The present article is aimed at establishing a pluripotent stem cell line from human placenta. METHODS: HAM-1 (stem cell line derived from human amniotic membranes) was established by the colonial cloning technique using aMEM culture medium containing 10 ng/ml of EGF, 10 ng/ml of hLIF and 10% fetal bovine serum. RESULTS: HAM-1 cells appeared to maintain a normal karyotype indefinitely in vitro and expressed markers characteristic of stem cells from mice and human, namely alkaline phosphatase. Also, these cells contributed to the formation of chimeric mouse embryoid bodies and gave rise to cells of all germ layers in vitro. CONCLUSIONS: This study demonstrates that human amniotic membranes derived stem cells have a wide developmental capability and might be utilized to regenerate different types of cells or tissues for transplantation therapy.

Amnion↗
PubMed2005

Context-dependent neuronal differentiation and germ layer induction of Smad4-/- and Cripto-/- embryonic stem cells.

Activation of transforming growth factor-beta (TGF-beta) receptors typically elicits mesodermal development, whereas inhibition of this pathway induces neural fates. In vitro differentiated mouse embryonic stem (ES) cells with deletion of the TGF-beta pathway-related factors Smad4 or Cripto exhibited increased numbers of neurons. Cripto-/- ES cells developed into neuroecto-/epidermal cell types, while Smad4-/- cells also displayed mesodermal differentiation. ES cell differentiation into catecholaminergic neurons showed that these ES cells retained their ability to develop into dopaminergic and serotonergic neurons with typical expression patterns of midbrain and hindbrain genes. In vivo, transplanted ES cells to the mouse striatum became small neuronal grafts, or large grafts with cell types from all germ layers independent of their ES cell genotype. This demonstrates that Smad4-/- and Cripto-/- ES cells favor a neural fate in vitro, but also express the mesodermal phenotype, implying that deletion of either Smad4 or Cripto is not sufficient to block nonneuronal tissue formation.

Animals↗
PubMed2006

Human embryonal tissues of all three germ layers can express the CD30 antigen. An immunohistochemical study of 30 fetuses coming after therapeutic abortions from week 8th to week 16th of gestation.

Originally, expression of the CD30 antigen was shown to be typical of the tumor cells of Hodgkin disease and of anaplastic large cell lymphomas. In reactive lymphoid tissue, CD30 is expressed only in a small population of activated lymphoid blasts. Since then, several reports have been published describing CD30 expression in non lymphoid tissues and neoplasms, such as embryonal carcinomas, seminomas, cultivated macrophages, histiocytic neoplastic cells, deciduals cells, and mesothelioma cells. In order to gain insight into the functions of CD30, given that it can mediate signals for cell proliferation and apoptosis, we studied the distribution of the antigen in different fetal archival paraffin-embedded tissues from week 8th to 16th of gestation. We investigated the immunohistochemical expression of CD30 in 30 paraffin-embedded tissue samples representing all three germ layers, using the monoclonal antibody Ber-H2 CD30 is expressed early in human fetal development (8th-10th week) in a wide variety of tissues, with the exception of the skin and thymus in which it is expressed later on. This is consistent with the observation that these organs are not fully differentiated before 10th and 13th week, respectively. No expression was observed in the cardiovascular and respiratory systems. The finding of CD30 expression in the terminal period of organogenesis, period, which is highly hormone related, implies that the antigen has an important role in cell development, maturation, and pathway to terminal differentiation in almost all fetal tissues and structures.

Abortion, Therapeutic↗
PubMed1984

Evidence that the ectoderm is the affected germ layer in the wingless mutant chick embryo.

We grafted normal flank ectoderm to the denuded presumptive wing bud mesoderm of stages 14-15 wingless embryos. When this was done, the wingless wing bud mesoderm was capable of inducing a ridge in the grafted ectoderm, maintaining that ridge, and growing out to form a wing. However, when stage 17-18 wingless wing bud mesoderm was combined with a normal leg bud ectodermal jacket, the recombinant bud failed to grow out to form a wing (Zwilling, '56a; and this report). When normal ectoderm was first grafted to a wingless host at stages 14-15, and the resulting stage 18 wing bud was removed and then the mesoderm recombined with a normal ectodermal jacket, the double recombinant bud could form a distally complete wing. However, these wings had some deficiencies compared to similar double recombinants made with normal mesoderm. These results show, first, that the ectoderm is affected by the wingless gene and, second, that there may be a prelimb bud stage interaction between wingless ectoderm and mesoderm such that, by stage 17, the wingless mesoderm becomes defective as a result of the ectodermally expressed mutation. Deficiencies in wingless mesoderm double recombinants indicate that the mesoderm may be sensitive to manipulation, possibly because the ectoderm has affected the mesoderm to some extent before stage 14. We believe it is not possible to determine the affected germ layer in wingless after the limb bud arises. However, after using the prelimb bud recombinant technique which we have designed, it becomes apparent that the ectoderm is affected by the wingless gene.

Animals↗
PubMed2000

Differentiation of human embryonic stem cells into embryoid bodies compromising the three embryonic germ layers.

BACKGROUND: Embryonic stem (ES) cells are lines of cells that are isolated from blastocysts. The murine ES cells were demonstrated to be true pluripotent cells as they differentiate into all embryonic lineages. Yet, in vitro differentiation of rhesus ES cells was somewhat inconsistent and disorganized. The recent isolation of human ES cells calls for exploring their pluripotential nature. MATERIALS AND METHODS: Human ES cells were grown in suspension to induce their differentiation into embryoid bodies (EBs). The differentiation status of the human ES cells and EBs was analyzed by following the expression pattern of several lineage-specific molecular markers using reverse transcription polymerase chain reaction (RT-PCR) and in situ hybridization. RESULTS: Here we report the induction in vitro of cystic embryoid bodies from human ES cells. Our findings demonstrate induction of expression of cell-specific genes during differentiation of the human ES cells into EBs. In the human EBs, we could show a characteristic regional expression of embryonic markers specific to different cellular lineages, namely, zeta-globin (mesoderm), neurofilament 68Kd (ectoderm), and alpha-fetoprotein (endoderm). Moreover, we present a synchronously pulsing embryoid body that expresses the myocardium marker alpha-cardiac actin. In addition, dissociating the embryoid bodies and plating the cells as monolayers results in multiple morphologies, among them cells with neuronal appearance that express neurofilament 68Kd chain. CONCLUSION: Human ES cells can reproducibly differentiate in vitro into EBs comprising the three embryonic germ layers. The ability to induce formation of human embryoid bodies that contain cells of neuronal, hematopoietic and cardiac origins will be useful in studying early human embryonic development as well as in transplantation medicine.

Animals↗
PubMed2004

Repression of nodal expression by maternal B1-type SOXs regulates germ layer formation in Xenopus and zebrafish.

B1-type SOXs (SOXs 1, 2, and 3) are the most evolutionarily conserved subgroup of the SOX transcription factor family. To study their maternal functions, we used the affinity-purified antibody antiSOX3c, which inhibits the binding of Xenopus SOX3 to target DNA sequences [Development. 130(2003)5609]. The antibody also cross-reacts with zebrafish embryos. When injected into fertilized Xenopus or zebrafish eggs, antiSOX3c caused a profound gastrulation defect; this defect could be rescued by the injection of RNA encoding SOX3DeltaC-EnR, a SOX3-engrailed repression domain chimera. In antiSOX3c-injected Xenopus embryos, normal animal-vegetal patterning of mesodermal and endodermal markers was disrupted, expression domains were shifted toward the animal pole, and the levels of the endodermal markers SOX17 and endodermin increased. In Xenopus, SOX3 acts as a negative regulator of Xnr5, which encodes a nodal-related TGFbeta-family protein. Two nodal-related proteins are expressed in the early zebrafish embryo, squint and cyclops; antiSOX3c-injection leads to an increase in the level of cyclops expression. In both Xenopus and zebrafish, the antiSOX3c phenotype was rescued by the injection of RNA encoding the nodal inhibitor Cerberus-short (CerS). In Xenopus, antiSOX3c's effects on endodermin expression were suppressed by injection of RNA encoding a dominant negative version of Mixer or a morpholino against SOX17alpha2, both of which act downstream of nodal signaling in the endoderm specification pathway. Based on these data, it appears that maternal B1-type SOX functions together with the VegT/beta-catenin system to regulate nodal expression and to establish the normal pattern of germ layer formation in Xenopus. A mechanistically conserved system appears to act in a similar manner in the zebrafish.

Amino Acid Sequence↗
PubMed1994

Placental teratoma with three-germ layer differentiation.

A rare case of placental teratoma is described. Major features were the presentation as a pedunculated mass from the fetal surface of the placenta, the mixture of different tissues derived from all three germ layers (skin with dermal appendages, ganglion-like cells, and nervous structures, gut structures, osteocartilagineous and smooth and striated muscle), and the absence of segmental organization.

Adult↗
PubMed1990

A Drosophila growth factor homolog, decapentaplegic, regulates homeotic gene expression within and across germ layers during midgut morphogenesis.

The decapentaplegic (dpp) gene product, a member of the transforming growth factor-beta family, is required in Drosophila embryos for normal gastrulation and the establishment of dorsal-ventral polarity in the embryo. dpp is also expressed at specific positions in the visceral mesoderm along the developing midgut. We find that mutations that eliminate the visceral mesoderm expression of dpp lead to defects in midgut morphogenesis and alter the spatially localized expression of the homeotic genes Sex combs reduced (Scr), Ultrabithorax (Ubx), and Antennapedia (Antp) in the visceral mesoderm. The extracellular dpp protein migrates from the visceral mesoderm across the apposing endodermal cell layer in a region of the endoderm that expresses the homeotic gene labial (lab). Mesodermal expression of dpp is required for the expression of lab in these endodermal cells indicating that dpp mediates an inductive interaction between the two germ layers. We propose that extracellular dpp protein regulates gut morphogenesis, in part, by regulating homeotic gene expression in the visceral mesoderm and endoderm of the developing midgut.

Animals↗
PubMed2006

Neurogenic effect of vascular endothelial growth factor during germ layer formation of human embryonic stem cells.

Vascular endothelial growth factor (VEGF), a potent mitogen for vascular endothelial cells, has been suggested as a modulator that is involved in neurogenesis as well as angiogenesis. Here, we directly examined the effect of VEGF on neuroectodermal differentiation using human embryonic stem cells (hESCs). VEGF treatment upregulated the expression of neuroectodermal genes (Sox1 and Nestin) during germ layer formation in embryoid bodies (EBs) and efficiently increased the number of neural rosettes expressing both Pax6 and Nestin. The neural progenitors generated from VEGF-treated EBs further differentiated into cells that showed a similar pattern of gene expression observed in the development of dopaminergic neurons upon terminal differentiation. These results support the neurogenic effect of VEGF on hESC differentiation.

Base Sequence↗
PubMed1983

Differential expression of lectin receptors in germ layers of the mouse egg cylinder and teratocarcinomas.

Receptors for three lectins with restricted specificities, namely fucose-binding protein of Lotus tetragonolobus (FBP), peanut agglutinin (PNA) and Dolichos biflorus agglutinin (DBA), were distinctively located in 6- and 7-day mouse embryos and in embryoid bodies of teratocarcinoma OTT6050 grown in vivo. Thus, FBP reacted mainly with the inner cells (embryonic ectoderm and teratocarcinoma stem cells), DBA reacted with the outer cells (endoderm) and PNA reacted with all the germ layers including mesoderm. Upon in vitro culture of the embryoid bodies, the exposed stem cells express DBA receptors. Since the receptors for the three lectins in teratocarcinomas are known to be carried by the large carbohydrate chains characteristic of early embryonic cells, the present result suggests that terminal structure of the large carbohydrates is altered according to the direction of the differentiation or to the position of the cells in embryos and in teratocarcinomas.

Amnion↗
PubMed1992

The vertebrate tail bud: three germ layers from one tissue.

The tail bud of amniote embryos comprises a mass of apparently undifferentiated mesenchymal cells located at the caudal limit of the embryo, representing the remains of Hensen's node and the primitive streak. These cells have the potential to give rise to a variety of different tissues including the posterior or 'secondary' neural tube, the tail gut, and somites and their derivatives. This seemingly homogeneous accumulation of cells therefore has the capacity to differentiate into tissues which in more cranial regions of the embryo are derived from cells of different germ layers. In this review, the tissue contributions of the tail bud in various vertebrate classes are discussed, with particular attention to the mesenchymal-to-epithelial transformation that characterizes the process of secondary neurulation, and which distinguishes it from the epithelial folding that occurs during primary neurulation in more cranial regions. Recent studies suggest that the transformation is accompanied by extensive changes in the cell surface oligosaccharide complement of the differentiating cells, and that the sialyted form of N-CAM is expressed both temporally and spatially in a manner that suggests a role for it in the process. The pluripotential nature of the tail bud mesenchyme may be revealed experimentally by grafting the tissue ectopically, or by culturing it on different substrata. In the latter case, the mesenchyme can be demonstrated to give rise to myocytes, chondrocytes, neuroepithelium and neural crest derivatives such as melanocytes, depending on the nature of the culture substratum. It is concluded that the tail bud mesenchyme represents a developing system which is readily amenable to experimentation and should provide insights into the general mechanisms of cell differentiation and transformation.

Amphibians↗
PubMed1998

Rac1 is required for the formation of three germ layers during gastrulation.

The Rac1, a member of the Rho family proteins, regulates actin organization of cytoskeleton and cell adhesion. We used genetic analysis to elucidate the role of Rac1 in mouse embryonic development. The rac1 deficient embryos showed numerous cell deaths in the space between the embryonic ectoderm and endoderm at the primitive streak stage. Investigation of the primary epiblast culture isolated from rac1 deficient embryos indicated that Rac1 is involved in lamellipodia formation, cell adhesion and cell migration in vivo. These results suggest that Rac1-mediated cell adhesion is essential for the formation of three germ layers during gastrulation.

Animals↗