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At least 505 records · Page 28Linked to original sources
PubMed2000

Endodermal Nodal-related signals and mesoderm induction in Xenopus.

In Xenopus, mesoderm induction by endoderm at the blastula stage is well documented, but the molecular nature of the endogenous inductive signals remains unknown. The carboxy-terminal fragment of Cerberus, designated Cer-S, provides a specific secreted antagonist of mesoderm-inducing Xenopus Nodal-Related (Xnr) factors. Cer-S does not inhibit signalling by other mesoderm inducers such as Activin, Derrière, Vg1 and BMP4, nor by the neural inducer Xnr3. In the present study we show that Cer-S blocks the induction of both dorsal and ventral mesoderm in animal-vegetal Nieuwkoop-type recombinants. During blastula stages Xnr1, Xnr2 and Xnr4 are expressed in a dorsal to ventral gradient in endodermal cells. Dose-response experiments using cer-S mRNA injections support the existence of an endogenous activity gradient of Xnrs. Xnr expression at blastula can be activated by the vegetal determinants VegT and Vg1 acting in synergy with dorsal (beta)-catenin. The data support a modified model for mesoderm induction in Xenopus, in which mesoderm induction is mediated by a gradient of multiple Nodal-related signals released by endoderm at the blastula stage.

Animals↗
PubMed2001

A bipotential precursor population for pancreas and liver within the embryonic endoderm.

The pancreas emerges independently from dorsal and ventral domains of embryonic gut endoderm. Gene inactivation experiments in mice have identified factors required for dorsal pancreas development, but factors that initiate the ventral pancreas have remained elusive. In this study, we investigated the hypothesis that the emergence of the ventral pancreas is related to the emergence of the liver. We find that the liver and ventral pancreas are specified at the same time and in the same general domain of cells. Using embryo tissue explantation experiments, we find that the default fate of the ventral foregut endoderm is to activate the pancreas gene program. FGF signalling from the cardiac mesoderm diverts this endoderm to express genes for liver instead of those for pancreas. No evidence was found to indicate that the cell type choice for pancreas or liver involves a selection for growth or viability. Cardiac mesoderm or FGF induces the local expression of sonic hedgehog, which in turn is inhibitory to pancreas but not to liver. The bipotential precursor cell population for pancreas and liver in embryonic development and its fate selection by FGF has features that appear to be recapitulated in the adult pancreas and are reflected in the evolution of these organs.

Animals↗
PubMed2002

Tail gut endoderm and gut/genitourinary/tail development: a new tissue-specific role for Hoxa13.

Hoxa13 is expressed early in the caudal mesoderm and endoderm of the developing hindgut. The tissue-specific roles of Hoxa13 function have not been described. Hand-foot-genital syndrome, a rare dominantly inherited human malformation syndrome characterized by distal extremity and genitourinary anomalies, is caused by mutations in the HOXA13 gene. We show evidence that one specific HOXA13 mutation likely acts as a dominant negative in vivo. When chick HFGa13 is overexpressed in the chick caudal endoderm early in development, caudal structural malformations occur. The phenotype is specific to HFGa13 expression in the posterior endoderm, and includes taillessness and severe gut/genitourinary (GGU) malformations. Finally, we show that chick HFGa13 negatively regulates expression of Hoxd13 and antagonizes functions of both endogenous Hoxa13 and Hoxd13 proteins. We suggest a fundamental role for epithelial specific expression of Hoxa13 in the epithelial-mesenchymal interaction necessary for tail growth and posterior GGU patterning.

Abnormalities, Multiple↗
PubMed2004

Aggregation of embryonic stem cells induces Nanog repression and primitive endoderm differentiation.

When embryonic stem cells are allowed to aggregate, the outer layer of the aggregated spheres (referred to as embryoid bodies) differentiates into primitive endoderm. This initial specification of cell lineage facilitates further differentiation of the inner mass of the embryoid bodies. These processes are considered to recapitulate early embryonic development from the blastocyst stage to the egg-cylinder stage. Formation of the primitive endoderm layer in the embryoid bodies was induced solely by aggregation of embryonic stem cells, in the presence of leukemia inhibitory factor/STAT3 and serum/BMP4, which were considered to be sufficient for embryonic stem cell self-renewal. Interestingly, cell aggregation by itself induced Nanog repression at the outer layer, which was essential for aggregation-induced primitive endoderm formation. These data illustrate aggregation-based cell-fate specification during early embryonic development, when downregulation of Nanog plays a crucial role.

Animals↗
PubMed2006

Neither maternal nor zygotic med-1/med-2 genes play a major role in specifying the Caenorhabditis elegans endoderm.

The med-1 and med-2 genes encode small, highly similar proteins related to GATA-type transcription factors and have been proposed as necessary for specification of both the mesoderm and the endoderm of Caenorhabditis elegans. However, we have previously presented evidence that neither maternal nor zygotic expression of the med-1/2 genes is necessary to specify the C. elegans endoderm. Contradicting our conclusions, a recent report presented evidence, based on presumed transgene-induced cosuppression, that the med-1/2 genes do indeed show an endoderm-specifying maternal effect. In this article, we reinvestigate med-2(-); med-1(-) embryos using a med-2- specific null allele instead of the chromosomal deficiences used previously and confirm our previous results: the large majority (approximately 84%) of med-2(-); med-1(-) embryos express gut granules. We also reinvestigate the possibility of a maternal med-1/2 effect by direct injection of med dsRNA into sensitized (med-deficient) hermaphrodites using the standard protocol known to be effective in ablating maternal transcripts, but again find no evidence for any significant maternal med-1/2 effect. We do, however, show that expression of gut granules in med-1/2-deficient embryos is exquisitely sensitive to RNAi against the vacuolar ATPase-encoding unc-32 gene [present on the same multicopy med-1(+)-containing transgenic balancer used in support of the maternal med-1/2 effect]. We thus suggest that the experimental evidence for a maternal med-1/2 effect should be reexamined and may instead reflect cosuppression caused by multiple transgenic unc-32 sequences, not med sequences.

Animals↗
PubMedDate not supplied

In vitro differentiation of mouse embryonic stem cells: enrichment of endodermal cells in the embryoid body.

Embryonic stem (ES) cells have the potential to differentiate into all three germ layers, providing new perspectives not only for embryonic development but also for the application in cell replacement therapies. Even though the formation of an embryoid body (EB) in a suspension culture has been the most popular method to differentiate ES cells into a wide range of cells, not much is known about the characteristics of EB cells. To this end, we investigated the process of EB formation in the suspension culture of ES cells at weekly intervals for up to 6 weeks. We observed that the central apoptotic area is most active in the first week of EB formation and that the cell adhesion molecules, except beta-catenin, are highly expressed throughout the examination period. The sequential expression of endodermal genes in EBs during the 6-week culture correlated closely with that of normal embryo development. The outer surface of EBs stained positive for alpha-fetoprotein and GATA-4. When isolated from the 2-week-old EB by trypsin treatment, these endodermal lineage cells matured in vitro into hepatocytes upon stimulation with various hepatotrophic factors. In conclusion, our results demonstrate that endodermal cells can be retrieved from EBs and matured into specific cell types, opening new therapeutic usage of these in vitro differentiated cells in the cell replacement therapy of various diseases.

Animals↗
PubMed2006

Endodermal cyst ventral to the lower brain stem.

A 28-year-old woman presented with a rare case of endodermal cyst located ventral to the lower brain stem manifesting as recurrent aseptic meningitis. Computed tomography and magnetic resonance imaging demonstrated a cystic mass located ventral to the lower brain stem and extending from the prepontine to the upper cervical (C-2) cistern. The lesion was totally removed through a retrosigmoid craniotomy and C1-2 hemilaminectomy. Histological and immunohistochemical examination showed the cyst was derived from the endoderm. The histological diagnosis was endodermal cyst. Early diagnosis and surgical removal are important for patients with these cysts.

Adult↗
PubMed2004

Retinoic acid induces Pdx1-positive endoderm in differentiating mouse embryonic stem cells.

We have generated an embryonic stem (ES) cell line in which sequences encoding green fluorescent protein (GFP) were targeted to the locus of the pancreatic-duodenal homeobox gene (Pdx1). Analysis of chimeric embryos derived from blastocyst injection of Pdx1(GFP/w) ES cells demonstrated that the pattern of GFP expression was consistent with that reported for the endogenous Pdx1 gene. By monitoring GFP expression during the course of ES cell differentiation, we have shown that retinoic acid (RA) can regulate the commitment of ES cells to form Pdx1(+) pancreatic endoderm. RA was most effective at inducing Pdx1 expression when added to cultures at day 4 of ES differentiation, a period corresponding to the end of gastrulation in the embryo. RT-PCR analysis showed that Pdx1-positive cells from day 8 cultures expressed the early endoderm markers Ptf1a, Foxa2, Hnf4alpha, Hnf1beta, and Hnf6, consistent with the notion that they corresponded to the early pancreatic endoderm present in the embryonic day 9.5 mouse embryo. These results demonstrate the utility of Pdx1(GFP/w) ES cells as a tool for monitoring the effects of factors that influence pancreatic differentiation from ES cells.

Animals↗
PubMed2005

The making of the liver: developmental competence in foregut endoderm and induction of the hepatogenic program.

The making of the vertebrate liver occurs in a two step process, beginning with the establishment of competence in the foregut endoderm to respond to signals from cardiac mesoderm, followed by the induction of liver-specific gene expression. Two winged helix transcription factors, Foxa1 and Foxa2, act in concert in hepatic specification. In a mouse model engineered to lack both of these genes in the foregut endoderm, no liver bud is formed and expression of even the earliest known hepatoblast markers does not occur. Furthermore, foregut endoderm derived from double mutant embryos is not responsive to inductive signals in vitro. The Foxa1/Foxa2 model is the first of a completely "liver-less mouse" and provides strong evidence for the competence model of hepatic induction.

Animals↗
PubMed1999

Endodermal sinus tumor of the maxillary sinus: a case report.

Endodermal sinus tumor is an uncommon malignant germ cell tumor that occurs in both gonadal and extragonadal tissues. Endodermal sinus tumors of the head and neck, exclusive of the central nervous system, are rare. We report a case of endodermal sinus tumor arising from the maxillary sinus in a 4-year-old boy. Combined treatment with radiation therapy and chemotherapy resulted in complete tumor regression.

Child, Preschool↗
PubMed1999

[Diagnosis and treatment of endodermal sinus tumor of the vagina].

OBJECTIVES: To describe the clinical characteristics and the role of chemotherapy in endodermal sinus tumor of the vagina. METHOD: Two patients with endodermal sinus tumor of the vagina were presented focusing on the clinical manifestations and outcome of the chemotherapy. RESULTS: Patient's age was quite young, 2 and 3 years old respectively. Vaginal bleeding and a polypoid and fragile tumor of the vagina were main clinical features. Elevated serum alpha-FP was found before chemotherapy and dropped dramatically to normal if the tumor was sensitive to chemotherapy. Diagnosis was made by pathology and alpha-FP immunohistochemical staining. Both two patient was well responded to cisplatin vincristine bleomycin (PVB) and cisplatin etoposide bleomycin (PEB) chemotherapy. Clinical and pathological complete remission was obtained after 2-3 courses of chemotherapy without radical surgery and radiotherapy. CONCLUSIONS: Endodermal sinus tumor of vagina in infant was very sensitive to the chemotherapy. Serum alpha-FP was very useful in diagnosis and monitoring of the disease.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1975

The embryonic rat parietal yolk sac. The role of the parietal endoderm in the biosynthesis of basement membrane collagen and glycoprotein in vitro.

Basement membrane biosynthesis in vitro was studied in a rapidly growing embryonic tissue, the rat parietal yolk sac. This tissue consists of a thick, nonvascular basement membrane (Reichert's membrane) separating two cellular layers (parietal endoderm and trophoblast). Morphologically, Reichert's membrane appeared similar to other basement membranes. Previous analysis of the amino acid and carbohydrate composition of acellular Reichert's membrane showed it to be typical of basement membranes isolated from other tissues and species. Analysis of [14-C]proline incorporation and hydroxy [14-C]proline synthesis during the third quarter ogestation in vitro showed that basement membrane collagen synthesis in the parietal yolk sac was maximal around the 14th day of gestation. At this time, basement membrane collagen represented nearly 10% of the newly synthesized protein. The collagen synthesized in this system was characteristic of basement membrane collagen in that about 11% of the total hydroxy [14-C]proline was present as the 3-isomer. In addition, after incubation in the presence of [14-C]lysine, 83 to 94% of the hydroxy[14-C]lysine was glycosylated, with the predominant form being glucosylgalactosylhydroxy[14-C]lysine. When the parietal endoderm and trophoblast were incubated separately with [14-C]proline, it was determined that the former was solely responsible for the synthesis of basement membrane collagen since essentially all of the 4-hydroxy[14-C]proline was associated with this cell type. Autoradiographic experiments with [3-H]glucosamine also served to localize the synthesis of noncollagen basement membrane glycoprotein components to the parietal endoderm. As with the results reported for basement membrane collagen secretion in embryonic chick lens cells, there appeared to be approximately a 60-min delay between the incorporation of [14-C]proline into protein and the secretion of collagen as measured by the appearance of 4-hydroxy[14-C]proline in the culture medium. Experiments utilizing [3H]glucosamine to monitor glycoprotein synthesis did not show a delay between the incorporation of [3H]glucosamine and the secretion of nondialyzable 3-H into the medium. The results obtained using the parietal yolk sac system to study basement membrane biosynthesis were compared to those previously obtained using the kidney glomerular and embryonic chick lens systems. It was concluded that the parietal yolk sac system is superior for a number of reasons: (a) the extracellular matrix appeared to contain only basement membrane components; there was no contamination by acid mucopolysaccharides or other types of collagen; (b) only a single cell type appeared to be responsible for the synthesis of basement membrane components; and (c) a relatively large percentage of the newly synthesized protein was basement membrane collagen.

Animals↗
PubMed2002

Targeted disruption of fibroblast growth factor receptor-1 blocks maturation of visceral endoderm and cavitation in mouse embryoid bodies.

The cellular response to fibroblast growth factors (FGFs) is mediated by receptor tyrosine kinases (FGFR-1 - 4) whose patterns of expression are spatially and temporally restricted during embryogenesis. These receptors have differential ligand binding capacities and are coupled to diverse signalling pathways. In the present study, we have characterized the ability of FGFR-1-deficient mouse embryonic stem (ES) cells to bind FGF-2 and to proliferate in the absence or presence of exogenous FGF-2. Under the same conditions, we also analysed the differentiation of FGFR-1-deficient ES cells into three dimensional, post-implantation, embryonic tissues, known as embryoid bodies (EBs). We show that the targeted disruption of FGFR-1 leads to a reduced binding of FGF-2 which has no significant effect on the proliferation of undifferentiated ES cells. In addition, lack of functional FGFR-1 in differentiating EBs leads to a reduced expression of the endoderm marker gene alpha-fetoprotein (AFP). This deregulation of the AFP gene correlates with defects in the formation of the visceral endoderm, proper differentiation of the ectoderm and thus the organization of the columnar epithelium, and a block of cavitation. Although the addition of exogenous FGF-2 further reduced the expression of AFPmRNA in differentiating mutant EBs, corresponding morphological changes were not observed. Our results indicate that FGFR-1 may play a vital role in endoderm formation.

Animals↗
PubMed2005

[A case of cervical endodermal cyst].

A very rare case involving an endodermal cyst of the cervical spinal canal was documented. In 1999, a 28-year-old male presented with mild tetraplegia due to a traffic accident and consequently, he was admitted to another hospital. Magnetic resonance imaging (MRI) performed at that time demonstrated a cervical cord cyst. He was treated conservatively and as a result, complete resolution of symptoms was achieved. Five years later, he presented with progressive right hemiparesis and was referred to our institute. MRI at the time of admission exhibited an intradural extramedullary cystic lesion on the ventral side of the spinal cord at the C5-6 levels, which was characterized by low intensity on T1-weighted, and by high intensity on T2-weighted images. The cyst, which had increased in size, compressed the spinal cord remarkably backward. The anterior central vertebrectomy approach was performed. Subtotal resection of the cyst wall was conducted due to its tight partical adhesion to the spinal cord. The vertebral defect was reconstructed with an autogenous iliac graft. According to histological findings the cyst wall consisted of a single layer of columnar epithelial cells with secretory granules and immunohistochemical examination revealed that the cyst wall was positive for cytokeratin 7. Symptoms improved immediately. Subsequently, the patient was discharged with good performance status. Endodermal cysts are very rare developmental cysts derived from the embryonic endodermal layer. Moreover, these lesions are usually located intradurally in the cervical and upper dorsal spine ventral to the spinal cord. Total removal of the cyst is recommended if it is possible. However, total resection is often difficult due to adhesion of the cyst wall to the neural tissue so invasive resection should be avoided. In such cases, follow-up MRI is necessary in order to exclude recurrence of the remnant lesion.

Adult↗
PubMed1990

[A strategy for immortalizing lines committed to endoderm, neuroectoderm or mesoderm from mouse teratocarcinoma].

With the aim of immortalizing embryonic cells fixed at early embryonic stages, various plasmids carrying the SV40 early region were introduced into the mouse embryonal carcinomas (EC) F9 and 1003. Only the construction PK4, in which the SV40 oncogenes are placed under the control of the adenovirus E1A promoter, led to the immortalization of the cells at the onset of differentiation. Clones corresponding to committed precursors of each embryonic lineage (neuroectoderm, mesoderm and endoderm) were then selected with high efficiency according to the following strategy: selection of immature cells which: have lost EC cell markers, keep a stable phenotype, are immortalized by the expression of the SV40 oncogenes and are still able to differentiate along a restricted lineage in vitro or in vivo. Examples of an endodermal precursor (H7) which differentiates into extraembryonic and embryonic endoderm, of a neuroectodermic clone (ICII) committed to a serotoninergic differentiation, and of a mesodermal osteogenic clone (CI) which gives rise to bone in vivo and in vitro, are given.

Adenoviridae↗
PubMed1989

Symptomatic intraspinal genuine endodermal epithelial cyst.

An intraspinal cervicodorsal endodermal epithelial cyst occurred in a 20-year-old man who experienced sudden paraparesis at the age of 6 years and subsequently developed progressive sensory disturbances. The patient underwent repeated surgical explorations indicating that the lesion may be difficult to identify. The cyst wall consisted of the outer smooth muscle and connective tissue and the inner epithelium that produced mucin and mucopolysaccharide. The intimate association between the epithelium and smooth muscle makes the cyst wall strikingly like the wall of the digestive tract or the respiratory passage and supports the endodermal origin of the cyst which must be distinguished from the neuroepithelial cyst. The pathogenesis of the endodermal epithelial cyst is suggested to be related to congenital maldevelopment of the notochord and the primitive gut.

Adult↗
PubMed1988

Cytodifferentiation of mouse visceral endoderm: study with a teratocarcinoma antiserum.

In this work we separated homogeneous embryoid bodies (EB); this population is composed of only endodermal vesicles of a visceral type. These EB were used to immunize rabbits. After absorption, the antisera were analyzed immunohistochemically in sections of 7.5- and 9-day-old mouse embryos, which showed a selective reaction to visceral endoderm. The cytodifferentiation of the visceral endoderm was studied.

Animals↗
PubMed1986

Scanning electron microscopical and histochemical study of the endoderm in the early chick embryo.

The endoderm of gastrulating chick embryos shows regional variations in cell shape and size. These were studied by scanning electron microscopy, histochemistry and immunofluorescence. Particular attention was given to the distribution of the cytoskeleton. Four zones of differing morphology were observed. The changing size and shape of these zones could be correlated with the entry of the definitive endoblast through the primitive streak, displacing existing primary hypoblast to the edges of the area pellucida. Endodermal cells were shown to have a well organised cytoskeleton. The cytoskeletons of individual cells were linked to give a cytoskeletal network extending across the endoderm as a whole.

Animals↗