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At least 523 records · Page 29Linked to original sources
PubMed2004

[Chorioallantoic membrane of fertilized avian eggs as a substrate for assessment of cancerous invasiveness].

PURPOSE: Invasiveness is a characteristic feature of malignant tumors considerably determining the prognosis of affected patients. For assessment, apart from in vitro procedures with limited validity, tests on animal models have been established which certainly should be replaced by alternative methods whenever possible. The chorioallantoic membrane (CAM) of fertilized avian eggs represents an epithelial-lined membrane composed of all three blastodermic germ layers. In an "in ovo" assay cancer cells can be applied to this membrane after sinking (CAM assay). Tumor growth and invasiveness should be monitored in succession. MATERIAL AND METHODS: Hybrid chorionic carcinoma trophoblast cells were expanded in cell culture and spread over the CAM of hen's eggs after sinking followed by further incubation at 37 degrees C. The growth and development of the tumors were assessed macroscopically and finally (immuno-)histologically. Additionally, cytokeratin 19 was determined by enzyme-linked immunosorbent assay following homogenization of the tumor cells. RESULTS. Macroscopically, development of solid tumors was evident. Histological and immunohistochemical analysis revealed initial intraepithelial followed by cone-shaped infiltration of the CAM by the tumor cells. Tumor growth could be correlated with quantitative cytokeratin 19 measurements. CONCLUSIONS: Histomorphological appearance of the tumors was comparable with those results achieved in an immunodeficient mouse model. In addition, the CAM assay can be used for qualitative assessment of invasiveness of malignant tumors and yields quantitative results regarding growth kinetics. In contrast to conventional animal models, there is no need for official approval. Finally, this method is economical and facilitates processing many cases within a short time.

Animals↗
PubMed1989

Promotion of osteogenesis by extra-embryonic epithelial in maxillary mesenchyme of the embryonic chick.

Maxillary mesenchyme (HH stages 19-21), separated from its epithelium and grown as a graft on the chorioallantoic membranes of host chick embryos, did not form membrane bone. However, when isolated maxillary mesenchyme was recombined directly with chorioallantoic endoderm or chorioallantoic ectoderm and then grafted, it did form membrane bone in 87.5 and 70% of cases, respectively. This novel finding of extra-embryonic epithelia eliciting an osteogenic response from membrane bone-forming mesenchyme indicates that the germ-layer origin of an epithelium does not necessarily restrict its potential to promote membrane bone formation.

Allantois↗
PubMed1983

Hybrids between F9 nullipotent teratocarcinoma and thymus cells produce multidifferentiated tumors in mice.

Hybrids between F9 teratocarcinoma and mouse thymus cells (FT2 hybrids) were obtained. All of the seven FT2 hybrid clones produced tumors containing varying amounts of differentiated tissues in addition to embryonal carcinoma. This is in contrast to the F9 parental cells which gave tumors formed exclusively of embryonal carcinoma cells. Two clones produced either undifferentiated tumors or tumors that had only small foci of ectoderm and/or endoderm derivatives. The five other FT2 clones differentiated into derivatives of the three primitive germ layers. Among these five clones, two produced tumors with large amounts of differentiated tissues which resembled the well-differentiated teratocarcinoma tumors produced by pluripotent embryonal carcinoma cell lines. On the whole, 71% of the observed sections of the 26 tumors that were thoroughly examined at 0.5-mm intervals showed ectoderm derivatives, 40% mesoderm derivatives, and 46% endoderm derivatives. This result shows that hybridization with thymus cells allows expression of pluripotentiality that was blocked in F9 teratocarcinoma cells.

Animals↗
PubMed1985

Analysis of the origins and early fates of neural crest cells in caudal regions of avian embryos.

Holmdahl divided vertebrate embryogenesis into two phases called primary and secondary body development. Three primary germ layers are delineated during primary body development and undergo morphogenesis to form primary organ rudiments. In contrast, during secondary body development, the tail bud (a mesenchymal mass of cells located at the caudal end of the embryo and derived principally from Hensen's node) directly forms secondary organ rudiments. We have been testing Holmdahl's concept of primary and secondary body development by mapping the embryonic structures that originate from the tail bud. In the present study, we examined the origins of neural crest cells in caudal regions of avian embryos and observed two populations: primary neural crest cells derived from ectoderm and secondary neural crest cells derived from tail bud. Both types of neural crest cells originate locally, and little or no displacement of these cells occurs along the longitudinal axis. Some secondary neural crest cells seem to colonize the surface epithelium, forming a mosaic derived from both ectoderm and tail bud. Other secondary neural crest cells form spinal ganglia, differentiating as sensory neurons, satellite cells, and Schwann cells. Despite their strikingly different origins and locations, primary and secondary neural crest cells give rise to similar structures.

Animals↗
PubMed1985

Variant embryonal carcinoma cells lacking SSEA-1 and Forsmann antigens remain developmentally pluripotent.

Six embryonal carcinoma (EC) cell lines that are resistant to the cytotoxic, galactose-specific lectin abrin were isolated from mutagenized populations of either PSA-1 or F9 cells. The LD10 for each of the variant lines was at least 150-fold greater than that for parental cells. Indirect cytotoxicity tests demonstrated that all of the variant cell lines lacked both Stage Specific Embryonic Antigen-1 (SSEA-1, less than 1% of wild-type levels) and Forsmann antigen (less than 5% of wild-type levels). When abrin-resistant cells were fused to previously isolated SSEA-1-negative cells (M. J. Rosenstraus (1983), Dev. Biol. 99, 318-323) that express Forsmann antigen, the resulting hybrids expressed SSEA-1. This implies the mutation conferring abrin resistance is in a different gene than that defined by the previously isolated mutation. Thus, we have identified two genes that are required for SSEA-1 expression, one of which also appears to be required for Forsmann antigen expression. The F9-derived variants differentiated into visceral-like or parietal-like endoderm when treated with retinoic acid in the absence or presence of 8-bromo-cAMP, respectively. PSA-1-derived variants formed differentiated teratocarcinomas containing derivatives of all three germ layers. Thus the SSEA-1 and Forsmann haptenic determinants are not required for EC cells to differentiate into a broad spectrum of cell types; nor do they appear to be involved in the cell-cell interactions that are postulated to regulate visceral versus parietal endoderm differentiation.

Abrin↗
PubMed1987

Changes in states of commitment of single animal pole blastomeres of Xenopus laevis.

The experiments described in this paper were designed to compare the normal fates of animal pole blastomeres of Xenopus laevis with their state of commitment. Single animal pole blastomeres were labeled with a lineage marker and transplanted into the blastocoels of host embryos of different stages. The distribution of labeled daughter cells in the tadpole reflects the state of commitment of the parent cell at the time of transplantation. It is known that cells from the animal pole of the early blastula normally contribute predominantly to ectoderm with a small, but significant, contribution to the mesoderm. We show that on transplantation to the blastocoels of late blastula host embryos these blastomeres are pluripotent, contributing to all three germ layers. At later stages the normal fate of these cells becomes restricted solely to ectoderm and concomitantly the proportion of pluripotent cells is reduced, although the results depend upon the stage of the host embryo. Blastomeres from late blastula donors transplanted to mid gastrulae contribute solely to ectoderm in 34% of cases; however, in earlier hosts, when the vegetal hemisphere cells have "mesoderm inducing" or "vegetalizing" activity, late blastula animal pole blastomeres contribute to mesoderm and endoderm rather than ectoderm. Thus during the blastula stage animal pole cells pass from pluripotency to a labile state of commitment to ectoderm.

Animals↗
PubMed1987

Fates of the blastomeres of the 16-cell stage Xenopus embryo.

The fate of each of the blastomeres in the 16-cell stage Xenopus embryo which had been carefully selected for stereotypic cleavages was determined by intracellularly marking a single blastomere with horseradish peroxidase and identifying the labeled progeny in the tailbud embryo by histochemistry. Each blastomere populated all three primary germ layers. The progeny of each blastomere were distributed characteristically both in phenotype and in location. For example, most organs were populated by the descendants of particular sets of blastomeres. Furthermore, within an organ the progeny of a single blastomere were restricted to defined spatial addresses. This study describes the fates of identified 16-cell stage blastomeres and demonstrates that they are distinct and predictable if embryos are preselected for stereotypic cleavages.

Animals↗
PubMed1987

Spatial and temporal expression pattern of N-cadherin cell adhesion molecules correlated with morphogenetic processes of chicken embryos.

N-cadherin is a Ca2+-dependent cell-cell adhesion molecule, which was identified in brain cells of mouse and chicken. In the present study, we have determined the pattern of expression of N-cadherin in chicken embryos at various stages by means of immunohistochemistry. N-cadherin was expressed in cells derived from all three primary germ layers. Its expression was transient in many tissues but permanent in others. The transient expression occurred in nephric tubules, skeletal muscles, mesenchymal tissues, endodermal organs, and epidermis, while the permanent expression occurred in nervous systems, lens, and myocardiac cells. Appearance or disappearance of N-cadherin could be generally correlated with morphogenetic events, such as rearrangement, segregation, or association of cells. Comparison of the expression pattern of N-cadherin with that of L-CAM and N-CAM determined by other workers suggests that there is some mechanism controlling expression of multiple classes of adhesion molecules. The pattern of expression of N-cadherin was generally complementary to that of L-CAM; that is, if N-cadherin appeared, L-CAM disappeared or vice versa. We also found cases in which N-cadherin was expressed in the same local regions as L-CAM. The distribution of N-cadherin was similar to that of N-CAM with some exceptions. Thus, N-cadherin and other cell-cell adhesion molecules seem to be expressed under a precise spatial and temporal control so as to be associated with a variety of morphogenetic events during development.

Animals↗
PubMed1989

Identification and characterization of polypeptide growth factors secreted by murine embryonal carcinoma cells.

Undifferentiated P19 and PC13 murine embryonal carcinoma (EC) cells have been analyzed for their ability to secrete polypeptide growth factors. This has been carried out by a combination of specific bioassays and the use of biochemical and immunological detection methods. Both P19 and PC13 EC cells secrete a platelet-derived growth factor (PDGF)-like growth factor, a type beta transforming growth factor, and insulin-like growth factors. In addition, PC13 EC cells secrete a heparin-binding growth factor functionally related to fibroblast growth factor, while P19 EC cells secrete transforming growth factor-alpha. This is the first demonstration for secretion of transforming growth factor-alpha by an equivalent of early embryonic cells. The possible paracrine growth stimulating effects of these growth factors have been tested on differentiated derivatives of P19 EC cells, corresponding to all three germ layers. The differences in growth factor production by various embryonal carcinoma cells are discussed in relation to the developmental origin of these cell lines.

Animals↗
PubMed1991

The M-twist gene of Mus is expressed in subsets of mesodermal cells and is closely related to the Xenopus X-twi and the Drosophila twist genes.

The twist gene was characterized in Drosophila as being necessary at gastrulation for the establishment of the mesodermal germ layer. It codes for a nuclear DNA-binding protein that is probably a transcription factor. We have cloned and sequenced the M-twist gene of Mus musculus. The deduced proteins encoded by the Mus, Xenopus, and Drosophila twist cDNAs, respectively, show a high degree of similarity. Northern blot analyses and in situ hybridizations reveal that the 1.7-kb murine M-twist m-RNA is present at early stages, starting at 8 days post coitum, and is expressed the most at 9.5 days in the cephalic and branchial mesectoderm, in some derivatives of the mesodermal layer (sclerotoma and somatopleura), and in the limb buds.

Animals↗
PubMed1991

Changes in temporal and spatial patterns of Gi protein expression in postimplantation mouse embryos.

We previously demonstrated the presence of GTP-binding proteins, G proteins, in the preimplantation mouse embryo (Jones and Schultz, 1990. Dev. Biol. 139, 250-262). These studies have been extended to the Day 6.5, 7.5, and 8.5 gestation embryo by employing PT-catalyzed ADP-ribosylation and immunoblotting techniques. We report here that the amount of embryonic alpha i increases from Day 6.5 to Day 7.5 of gestation, and remains at about the same level at Day 8.5. In contrast, the extent of PT-catalyzed ADP-ribosylation of Gi alpha protein(s) decreases between Days 6.5 and 7.5--this decrease is global and not restricted to a particular germ layer of the Day 7.5 embryo--and then dramatically increases by Day 8.5 of gestation. In the Day 8.5 gestation embryo, the extent of PT-catalyzed ADP-ribosylation of Gi alpha proteins increases along the anterior-posterior axis, whereas the amount of immunoreactive alpha i subunit decreases along this axis. By using a combination of PT-catalyzed ADP-ribosylation and immunoprecipitation with antisera specific for alpha i1, alpha i2, or alpha i3, we report that all three alpha i subtypes are present in the Day 8.5 gestation mouse embryo. Results of these experiments suggest that an activation of Gi proteins occurs between Days 6.5 and 7.5 of gestation in the postimplantation embryo, a time during which the embryo is gastrulating, and that a decreasing gradient of activation exists along the anterior to posterior axis in the Day 8.5 gestation embryo. Last, we report that oocytes, eggs, and preimplantation embryos possess all three subtypes of alpha i.

Amino Acid Sequence↗
PubMed1984

Rabbit antiserum against a purified surface glycoprotein decompacts mouse preimplantation embryos and reacts with specific adult tissues.

A rabbit antiserum against a purified embryonal carcinoma (EC) cell surface glycoprotein interferes with cell-cell interaction in mouse preimplantation embryos. The 123 kD glycoprotein seems not to be an integral membrane component. The reactivity pattern of the antiserum was studied by immunofluorescence on cryostat sections of post-implantation embryos and of adult tissues. During embryonic development positive reactions were found on all epithelial cells, irrespective of their germ layer origin. Epithelial cells of adult tissues--tongue, uterus, gut, kidney, trachea and liver--react with the antibodies. The results are compared with cell-adhesive molecules previously described on EC cells and preimplantation embryos.

Animals↗
PubMed1984

Developmental characteristics of somatic cell hybrids between totipotent mouse teratocarcinoma and rat intestinal villus cells.

Hybrids between mouse PCC4-azal teratocarcinoma cells and rat epithelial intestinal villus cells (PCI hybrids) are phenotypically teratocarcinoma cells. They express several teratocarcinoma-specific traits but do not express functions specific for differentiated cells. Tumour formation is partially or completely suppressed. Some of the hybrids show more extensive differentiation both in vitro and in vivo than the PCC4-azal parental line. The hybrids are capable of endoderm formation in monolayer cultures and of the formation of embryoid bodies in suspension cultures. Two of the tumour-forming hybrids generate derivatives of all three germ layers, whereas differentiation in the PCC4-azal tumours is restricted to the formation of primitive neuronal tissues.

Animals↗
PubMed1989

Teratoma of the pituitary gland in a young male rat.

A pituitary teratoma was found in a 5-week-old (37-day-old) male Donryu rat. The tumour (10 x 11 x 9 mm) was round in shape and white in colour. The cut surface was solid without haemorrhagic or cystic change. Histologically, it was composed of various kinds of tissue components including mature and immature elements derived from the three embryonic germ layers, i.e., nervous tissue, cartilage, bone, squamous epithelial element, glandular element lined by one or more layers of ciliated columnar or cuboidal epithelial cells, striated muscle tissue, adipose tissue and connective tissue. Neuroepithelial rosettes and immature or embryonal epithelium as well as immature cartilage were intermingled with mature somatic tissues.

Animals↗
PubMed1989

SPARC: a Ca2+-binding extracellular protein associated with endothelial cell injury and proliferation.

SPARC (Secreted Protein that is Acidic and Rich in Cysteine) is a Ca2+-binding, stress-related protein released in vitro by both malignant and normal cells derived from all primordial germ layers. It is specifically elevated in endothelial cells as a result of "culture shock" (characterized by high levels of proliferation and migration) and exhibits density-dependent secretion. Exposure of bovine aortic endothelial cells to endotoxin results in a 70-100% increase in secreted protein, with a three-fold increase in SPARC. Immunofluorescence histochemistry on mouse tissues revealed (a) a preferential association of SPARC with highly proliferative cells (e.g., gut epithelia, mammary gland, and epidermis), (b) a cell surface or stromal location in thymus, lung, and salivary gland, (c) staining of epididymidal epithelium and testicular cells, and (d) an association with somites of 14 d mouse embryos. We envision SPARC as an extracellular modulator of Ca2+ and other cation-sensitive proteins/proteinases, that facilitates cellular proliferation in response to injury and to developmental signals.

Animals↗
PubMed1993

Characterization of acute rat parvovirus infection by in situ hybridization.

In situ hybridization and virus titration were used to characterize early stages of rat virus (RV) infection of rat pups after oronasal inoculation. Results suggest that virus enters through the lung and that early viremia leads rapidly to pantropic infection. Cells derived from all three germ layers were infected with RV, but those of endodermal and mesodermal origin were the predominant targets. Infection of vascular endothelium was widespread and was associated with hemorrhage and infarction in the brain. Convalescence from acute infection was accompanied by mononuclear cell infiltrates at sites containing RV DNA. Viral DNA was also detected in endothelium, fibroblasts and smooth muscle myofibers four weeks after inoculation. Further examination of these cells as potential sites of persistent infection is warranted.

Animals↗
PubMedDate not supplied

Teratomas of the head and neck.

Teratomas of the head and neck are uncommon. They are composed of tissues from all three germ layers with varying degrees of differentiation. They arise from pluripotent stem cells and ectopic embryonic nongerm cells. Head and neck teratomas most commonly emerge during the neonatal period and are associated with airway obstruction and high rates of mortality in untreated patients. The tumors are usually benign, but when found during adulthood, they have a high incidence of malignancy. The most common site of occurrence is the cervical region and the nasopharynx. We presented a rare case of teratoma originating from the base of the tongue. This case is an example of the development of teratoma by pinching off of remnants of the three germinal areas, which become marginated in the normal migratory pathway as the different structures of the head and neck develop. The remnants developed into the predetermined organ systems, giving rise to the heterotopic tissues encountered. The recommended treatment for head and neck teratomas is surgical excision. When a patient is experiencing respiratory difficulty, establishment of an airway is a priority.

Child, Preschool↗