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 1,027 records · Page 57Linked to original sources
PubMed2003

An overview of stem cell research and regulatory issues.

Stem cells are noted for their ability to self-renew and differentiate into a variety of cell types. Some stem cells, described as totipotent cells, have tremendous capacity to self-renew and differentiate. Embryonic stem cells have pluripotent capacity, able to form tissues of all 3 germ layers but unable to form an entire live being. Research with embryonic stem cells has enabled investigators to make substantial gains in developmental biology, therapeutic tissue engineering, and reproductive cloning. However, with these remarkable opportunities many ethical challenges arise, which are largely based on concerns for safety, efficacy, resource allocation, and methods of harvesting stem cells. Discussing the moral and legal status of the human embryo is critical to the debate on stem cell ethics. Religious perspectives and political events leading to regulation of stem cell research are presented and discussed, with special attention directed toward the use of embryonic stem cells for therapeutic and reproductive cloning. Adult stem cells were previously thought to have a restricted capacity to differentiate; however, several reports have described their plasticity potential. Furthermore, there have been close ties between the behavior of stem cells and cancer cells. True eradication of cancer will require a deeper understanding of stem cell biology. This article was written to inform medical scientists and practicing clinicians across the spectrum of medical education about the research and regulatory issues affecting the future of stem cell therapy.

Animals↗
PubMed2005

Premeiotic origin of teratomas: is meiosis required for differentiation into mature tissues?

By virtue of meiotic cell division, primordial germ cells with heterozygous alleles develop into postmeiotic germ cells with homozygous alleles. Female and male germ cells may develop tumors--so-called teratomas--with a unique coexistence of a variety of histological elements from all three embryonic germ layers. In particular, mature teratomas consist exclusively of developmentally mature tissues whereas immature teratomas contain variable amounts of mature and immature tissues. In this study, we report genetic analysis of individual tissue components from mature and immature teratomas. The majority of mature teratomas showed consistent and concordant homozygous alleles in all selectively procured tissue components. In a small subset of mature teratomas, we observed discordant homozygous alleles. In contrast, immature teratomatous tissue revealed a heterozygous genotype. Remarkably, mature tissue components within immature teratoma revealed homozygosity. The findings suggest that immature teratomas and at least a subset of mature teratomas may originate from premeiotic cells, and implicate that meiosis may be required for differentiation into mature tissues.

Alleles↗
PubMed2005

Ber-H2 (CD30) immunohistochemical staining of human fetal tissues.

OBJECTIVE: CD30 antigen has long been considered to be restricted to the tumour cells of Hodgkin's disease and of anaplastic large cell lymphoma as well as to T and B activated lymphocytes. It is now apparent that the range of normal and neoplastic cells, which may express CD30 antigen, is much wider than was at first thought. In order to gain insight into the physiological function of CD30 antigen, we studied the distribution of its expression in the tissues of fetuses from week 8th to week 16th. MATERIALS AND METHODS: We investigated the immunohistochemical expression of CD30 antigen in paraffin-embedded tissue samples representing all systems from 30 fetuses after therapeutic abortion at 8th to 10th and 12th to 16th week of gestation, respectively, using the monoclonal antibody Ber-H2. RESULTS: Our results demonstrated that CD30 is expressed early in human fetal development (8th to 10th week of gestation) in several fetal tissues derived from all three germ layers (gastrointestinal tract, special glands of the postpharyngeal foregut, urinary, musculoskeletal, reproductive, nervous, endocrine systems), with the exception of the skin and hematolymphoid system (thymus), in which the antigen is expressed later on (10th week onwards). Expression of CD30 was restricted to the hematolymphoid system in the 12-16 weeks of gestation. No expression of the marker was observed in the respiratory and cardiovascular systems during the entire period examined. CONCLUSIONS: CD30 antigen is of importance in cell development, and proliferation. It is also pathway-related to terminal differentiation in many fetal tissues and organs.

Antibodies, Monoclonal↗
PubMed1999

Pax genes and their role in organogenesis.

Pax genes have been cloned on the basis of their homology to the Drosophila segmentation gene paired. They share a common domain, the paired domain, that is sufficient to mediate sequence-specific DNA binding. Thus far, nine members have been characterized, which exhibit highly restricted temporal and spatial expression patterns. The analysis of mouse mutants has revealed their crucial role in the formation of a variety of tissues. In particular, they are involved in the regulation of early steps in organ development. They act to define the regional specification of distinct germ layers.

Animals↗
PubMed1976

The developmental analysis of an embryonic lethal (C6H) in the mouse.

A development study of the effects of the C6H allele at the albino locus has identified the C6H homozygote as an early postimplantation lethal. Homozygous C6H embryos can first be recognized at 6 1/2-7 days of gestation by abnormalities of the ectoplacental and parietal endodern. At 7 1/2 days, mutant embryos appear severely retarded with obvious abnormalities in all germ layers. All C6H homozygotes are dead and resorbed by 8 days of development. It is proposed that the mutation interferes with the normal differentiation of the parietal endoderm, ectoplacental cone and extra-embryonic ectoderm of the egg cyclinder.

Alleles↗
PubMed1999

Mature presacral teratoma in an adult male: a case report.

Presacral teratomas are rare tumors derived from more than one embryonic germ layer and are usually diagnosed in infancy. It has been estimated that the incidence of presacral teratoma in children ranges from 1 in 30,000 to 1 in 43,000 live births. However, the diagnosis of these tumors in adults is extremely rare. H. Head et al. reviewed the world literature in 1975 and found only 71 reported cases. Since that time, an additional 14 cases have been reported, and only one of these was found in the United States. This study reports a case of an adult male who presented with recurrent infected pilonidal cysts that proved to be benign presacral teratoma at biopsy. The patient underwent resection by left hemisacrectomy and primary closure using a posterior approach and, since this procedure, has had no evidence of recurrence. The case is presented along with a review of the relevant literature.

Adult↗
PubMed1999

[Manipulation of angiopoietc/hematopoietic potentials in the avian embryo].

The hypothesis that the endothelial and hemopoietic lineages have a common ontogenic origin is currently being revived. We have shown previously by means of quail/chick transplantations that two subsets of the mesoderm give rise to endothelial precursors: a dorsal one, the somite, produces pure angioblasts (angiopoietic potential), while a ventral one, the splanchnopleural mesoderm, gives rise to progenitors with a dual endothelial and hemopoietic potential (hemangiopoietic potential). To investigate the cellular and molecular controls of the angiopoietic/hemangiopoietic potential, we devised an in vivo assay based on the polarized homing of hemopoietic cell precursors to the floor of the aorta detectable in the quail/chick model. In the present work, quail mesoderm was grafted, after various pretreatments, onto the splanchnopleure of a chick host; the homing pattern and nature of graft-derived cells were analyzed thereafter using the QH1 monoclonal antibody which recognizes both quail endothelial and hemopoietic lineages. We report that transient contact with endoderm or ectoderm could change the behavior of cells derived from treated mesoderm, and that the effect of these germ layers could be mimicked by treatment with several growth factors VEGF, bFGF, TGF beta 1, EGF and TGF alpha, known to be involved in endothelial commitment and proliferation, and/or hemopoietic processes. The endoderm induced a hemangiopoietic potential in the associated mesoderm. Indeed, the association of paraxial or somatopleural mesoderm with endoderm promoted the "ventral homing" and the production of hemopoietic cells from mesoderm not normally endowed with this potential. The hemangiopoietic induction by endoderm could be mimicked by VEGF, bFGF and TGF beta 1. In contrast, a contact with ectoderm or EGF/TGF alpha treatments totally abrogated the hemangiopoietic capacity of the splanchnopleural mesoderm which produced pure angioblasts with no "ventral homing" behavior. We postulate that two gradients, one positive and one negative, modulate the angiopoietic/hemangiopoietic potential of the mesoderm.

Animals↗
PubMed1999

Neuralization of the Xenopus embryo by inhibition of p300/ CREB-binding protein function.

p300/ CREB-binding protein (CBP) is a transcriptional coactivator for a plethora of transcription factors and plays critical roles in signal transduction pathways. We report that the inhibition of p300/CBP function in the Xenopus embryo abolishes non-neural tissue formation and, strikingly, initiates neural induction and primary neurogenesis in the entire embryo. The observed neuralization is achieved in the absence of anterior or posterior gene expression, suggesting that neural fate activation and anterior patterning may represent distinct molecular events. We further demonstrate that the neuralizing and anteriorizing activities of chordin and noggin are separable properties of these neural inducers. This study reveals that all embryonic cells possess intrinsic neuralizing capability and that p300/CBP function is essential for embryonic germ layer formation and neural fate suppression during vertebrate embryogenesis.

Animals↗
PubMed2000

Adult sacrococcygeal teratomas.

We report a rare case of a benign adult sacrococcygeal teratoma discovered during pregnancy. The cystic mass was confirmed on CT scan and magnetic resonance imaging. In the fifth postpartum month, three cysts (1, 2.5, and 6 cm) were excised. Pathologically, the specimens contained differentiated tissue from all three germ layers, including endocrine tissue within the ectopic exocrine pancreas.

Adult↗
PubMed2000

Primary thyroid teratomas: a clinicopathologic study of 30 cases.

BACKGROUND: Primary thyroid teratomas are rare thyroid gland neoplasms of germ cell derivation that display features of trilineage differentiation. METHODS: The histologic and immunophenotypic features of 30 cases of thyroid teratomas were reviewed, patient follow-up was obtained, and the results were analyzed statistically. RESULTS: The patients included 15 females and 15 males ages newborn-56 years (mean, 12.4 years). All patients presented clinically with a mass in the thyroid, ranging in size from 2.0-13 cm in greatest dimension (mean, 6.0 cm). Histologically, the tumors usually were well circumscribed, although occasionally infiltrative into the thyroid parenchyma. Derivatives of all three germ layers (ectoderm, mesoderm, and endoderm) were present in varying degrees of maturity. The tumors were divided into benign (n = 7 tumors), immature (n = 14 tumors), and malignant (n = 9 tumors) as determined by an increasing percentage of tumor volume comprised of primitive mesenchymal or neural-type tissue. All the microscopically malignant tumors occurred in the adult population. Surgical excision was performed in 28 patients, followed by adjuvant therapy in 5 patients. Follow-up was obtained in 26 patients; 8 patients had died from or with tumor (5 neonates with immature histology and 3 adults with malignant histology; mean, 0.6 years) and 18 patients were alive with no evidence of disease at a mean of 16.9 years of follow-up. CONCLUSIONS: Thyroid teratomas are rare neoplasms that can be divided into three types depending on the presence and proportion of the immature component. The outcome is dependent largely on the age of the patient, the size of the tumor at the time of initial presentation, and the presence and proportion of immaturity. Surgical excision is the treatment of choice, with adjuvant therapy reserved for the malignant cases.

Adolescent↗
PubMed2000

goosecoid expression represses Brachyury in embryonic stem cells and affects craniofacial development in chimeric mice.

The homeobox gene goosecoid, originally identified in Xenopus, is expressed in the organizer or its equivalent during gastrulation in the frog, chick, zebrafish and mouse. To investigate the role of goosecoid in mouse development, we have generated embryonic stem cells that stably overexpress the murine homolog of goosecoid. These cells show a repression of the gastrulation-associated gene Brachyury. Interestingly, repression of Brachyury is conserved between Xenopus and mouse despite the lack of conservation of the Brachyury promoter. Further characterization of the goosecoid-overexpressing ES cells revealed that they maintain the expression of stage-specific embryonic antigen-1, and teratomas derived from goosecoid-overexpressing cells show the presence of cell types derived from all three germ layers. Some highly chimeric mice derived from goosecoid-overexpressing cells displayed skull defects. These observations suggest that goosecoid may play a role in specification of anterior mesendodermal fates and specifically in mouse craniofacial development.

Animals↗
PubMed2000

Congenital nasopharyngeal teratoma (epignathus).

The case report of a congenital nasopharyngeal teratoma presented as an intra-amniotic sac mass was described. Histologically, the tumor was composed of highly differentiated tissue derived from three germ layers. Those tissues were partially developed as infant organs with a central core made up by bone. Haphazardly arrangement of such tissues with disorganized sketal axis helped in differentiating the mass from an asymmetric twins. The evidence of tumor attachment was seen at the retro-uvular region.

Adult↗
PubMed2000

Coregulation of anterior and posterior mesendodermal development by a hairy-related transcriptional repressor.

During embryonic development in vertebrates, the endoderm becomes patterned along the anteroposterior axis to produce distinct derivatives. How this regulation is controlled is not well understood. We report that the zebrafish hairy/enhancer of split [E(spl)]-related gene her5 plays a critical role in this process. At gastrulation, following endoderm induction and further cell interaction processes including a local release of Notch/Delta signaling, her5 expression is progressively excluded from the presumptive anterior- and posteriormost mesendodermal territories to become restricted to an adjacent subpopulation of dorsal endodermal precursors. Ectopic misexpressions of wild-type and mutant forms of her5 reveal that her5 functions primarily within the endodermal/endmost mesendodermal germ layer to inhibit cell participation to the endmost-fated mesendoderm. In this process, her5 acts as an active transcriptional repressor. These features are strikingly reminiscent of the function of Drosophila Hairy/E(spl) factors in cell fate decisions. Our results provide the first model for vertebrate endoderm patterning where an early regulatory step at gastrulation, mediated by her5 controls cell contribution jointly to the anterior- and posteriormost mesendodermal regions.

Amino Acid Sequence↗
PubMedDate not supplied

Prune-belly syndrome associated with extra-abdominal abnormalities in a 7-year-old boy.

Prune-belly syndrome (PBS) is an association of abdominal wall deficiency, genitourinary anomalies, and in males, cryptorchidism. Other congenital anomalies are associated with PBS, particularly musculoskeletal deformities and gastrointestinal tract anomalies. In this report, a seven-year-old boy with PBS had mega cisterna magna variant, microcornea, aortic stenosis with bicuspid aortic valves, cholelithiasis, and Hirschsprung's disease. Coexistence of these abnormalities with PBS supports the concept of PBS being caused by an early disturbance of not only mesodermal development but also of the other germ layers. There was maternal ingestion of drugs in the 1st month of gestation. All cases with PBS should be evaluated thoroughly for extra-abdominal abnormalities resulting from disturbances of ectodermal and endodermal development. Even though disturbances related to ectodermal and endodermal development may be asymptomatic, early diagnosis of the disturbances may help in preventing possible future problems.

Abnormalities, Drug-Induced↗
PubMed2000

Mature teratoma of the nasal vestibule: a case report.

Teratomas are rare congenital neoplasms that arise from pluripotent cells. They consist of tissue from all three embryonic germ layers. According to most studies, teratomas of the head and neck account for only 2 to 9% of all cases. In this article, we report the first case of a teratoma of the nasal vestibule in a newborn. We also discuss methods of diagnosis and treatment of upper airway teratomas, and we include a brief review of the literature.

Anesthesia, Local↗
PubMed1975

[Mouse teratocarcinoma: differentiation in cultures of a multipotential primitive cell line (author's transl)].

A line of primitive cells of teratocarcinoma is able of differentiating during in vitro cultures. The differentiated cell types correspond to derivatives of the three germ layers. They appear according to a reproducible schedule. The differentiated cell types exhibit a normal karyotype. They have lost their tumorigenicity and have a limited life span. Agregates containing various numbers of primitive cells have been prepared and plated in culture dishes. Their study shows that the first differentiated cell types appear only when the agregates are greater than a certain critical mass. Primitive cells carry on their surface the F9 but not the H-2 antigen. During differentiation in culture, the H-2 antigen appears rapidly on certain cells. The fraction of H-2-carrying cells increases as a function of time while that of F9-carrying cells decreases.

Animals↗
PubMedDate not supplied

Mouse embryonic stem (ES) cell lines established from neuronal cell-derived cloned blastocysts.

We have established mouse embryonic stem (ES) cell lines from blastocysts derived by transfer of nuclei of fetal neuronal cells. These neuronal cell-derived embryonic cell lines had properties that characterize them as ES cells, including typical cell markers and alkaline phosphatase activity. Moreover, the cells had a normal karyotype and were pluripotent, as they were capable of differentiating into all three germ layers. Although they were derived from neuronal donor nuclei, the cells no longer expressed neuronal markers; however, they were capable of differentiating into cells with neuronal characteristics. These results suggest that the clone-derived cells have fully acquired an ES cell character. Thus, ES cells can be derived from embryos resulting from nuclear transfer, which results in reprogramming of the genetic information and acquisition of pluripotency. ES cells established from somatic cell-derived blastocysts could be useful not only as research tools for studying reprogramming but also as models for cell-based transplantation therapy.

Alkaline Phosphatase↗
PubMed1975

Murine ovarian teratoma.

A unilateral ovarian teratoma was observed in a C3H/HeN breeder mouse. Tissues originating form the 3 embryonal germ layers were present in the tumor. A focus suggestive of epithelial malignant transformation was noted; however, neither metastasis nor invasion into the surrounding capsule was found.

Animals↗