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Results 451 - 500 of 1017
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Tam P P - - 1997
The cardiogenic potency of cells in the epiblast of the early primitive-streak stage (early PS) embryo was tested by heterotopic transplantation. The results of this study show that cells in the anterior and posterior epiblast of the early PS-stage embryos have similar cardiogenic potency, and that they differentiated to heart ...
Moreno-Rodriguez R A - - 1997
BACKGROUND: We investigated potential early asymmetries in the distribution of mesenchymal cells within the inferior and superior AV cushions in the developing chick heart. METHODS: Chick embryos stages 16-20 HH were fixed, embedded in polyacrylamide, and the cell nuclei stained with propidium iodide. Cells counts were determined within the cardiac ...
Stringa E - - 1997
Specific binding to the lectin, peanut agglutinin (PNA), has been reported in embryonic precartilage tissues, including the condensing limb bud blastema and the caudal half of the developing somite. The present study aimed to test the hypothesis that PNA-binding may be a surface characteristic of chondroprogenitor cells residing within noncartilage ...
Vargesson N - - 1997
We have produced detailed fate maps for mesenchyme and apical ridge of a stage 20 chick wing bud. The fate maps of the mesenchyme show that most of the wing arises from the posterior half of the bud. Subapical mesenchyme gives rise to digits. Cell populations beneath the ridge in ...
Brockes J P - - 1997
The ability to regenerate complex structures is widespread in metazoan phylogeny, but among vertebrates the urodele amphibians are exceptional. Adult urodeles can regenerate their limbs by local formation of a mesenchymal growth zone or blastema. The generation of blastemal cells depends not only on the local extracellular environment after amputation ...
Peterka M - - 1997
Hypoplasia of the medial nasal process has been reported in chick embryos on embryonic day (ED) 5, 24 h after their exposure to hydrocortisone (HC). As a result, the cleft beak occurs in 80-100% of specimens on ED 9. In order to analyze its influence on cell proliferation, HC was ...
Kanatsu M - - 1997
During mammalian gastrulation, posterior part of primitive ectoderm differentiates into subsets of mesoderm cells, the most proximal portion of which subsequently gives rise to vascular endothelial cells and hematopoietic cells. To analyze this process in which the potency of multipotent epiblast cells is restricted progressively into hematopoietic cell lineages, we ...
Löfberg J - - 1997
The hypochord of the axolotl embryo is first visible at an early tailbud stage, forming a rod-like structure, situated immediately under the notochord. A profusion of extracellular matrix fibrils is attached to the dorsolateral regions of the hypochord, linking it with the somites. A basal lamina develops around the hypochord, ...
Laufer E - - 1997
The apical ectodermal ridge of the vertebrate limb bud lies at the junction of the dorsal and ventral ectoderm and directs patterning of the growing limb. Its formation is directed by the boundary between cells that do and cells that do not express the gene Radical fringe. This is similar ...
Sanders E J - - 1997
We have examined the distribution of cells at an early stage of the cell death process in gastrulating chick and mouse embryos, using a DNA nick end-labelling technique to label nuclei that are undergoing DNA fragmentation in situ. In the chick embryo, the incidence of nuclei showing DNA fragmentation was ...
Kanki J P - - 1997
In order to understand the developmental mechanisms of posterior body formation in the zebrafish, a fate map of the zebrafish tailbud was generated along with a detailed analysis of tailbud cell movements. The fate map of the zebrafish tailbud shows that it contains tissue-restricted domains and is not a homogeneous ...
Dvorák P - - 1997
Several peptide growth factors, including members of the fibroblast growth factor (FGF) superfamily, are potential inducers of mesoderm in vertebrates. Receptor binding of basic FGF (FGF-2) is promoted by cell surface or extracellular matrix proteoglycans. The substantial biosynthesis of proteoglycans by embryonic cells (called embryoglycans) and their potential role as ...
Rahman M M - - 1997
We have investigated the expression and the localization of annexin V and annexin VI during the development of rat fetal limb buds by immunoblot and immunocytochemical analysis. Neither annexin V nor annexin VI was detectable in undifferentiated mesenchymal cells in limb buds of the day-13-day-16 rat fetus. Skeletal muscles, whose ...
Eisenberg C A - - 1997
The beginning of mesodermal development involves the aggregation of newly gastrulated cells into epithelial fields, as a prelude to organ formation. To analyze the molecular regulation of this initial patterning, we have focused on the Wnt family of secreted signaling proteins, molecules which have been shown to promote embryonic patterning ...
Wallace J A - - 1996
1. The development of tyrosine hydroxylase-immunoreactive (TH-IR) neurons was examined in the spinal cord of the chick embryo and hatchling. 2. Two groups of TH-IR cells are described, both of which appear to reach their full complement in number relatively late in embryonic development. One group is comprised of numerous ...
Beiman M - - 1996
A Drosophila FGF receptor homolog (DFGF-R2/DFRI) termed Heartless (Htl) is expressed in the embryonic mesoderm. The phenotypes of null mutant embryos demonstrated that Htl is a central player that is required for the development of several mesodermal lineages. No abnormalities in the primary specification of the mesoderm were observed. The ...
Yokouchi Y - - 1996
During limb development, the mesenchymal cells in restricted areas of limb bud, anterior necrotic zone, posterior necrotic zone, opaque zone and interdigital necrotic zones, are eliminated by programmed cell death. The transcripts of bone morphogenetic protein (Bmp)-2 and -4 were first detected in the areas where cell death was observed, ...
Pagan S M - - 1996
Using Sonic Hedgehog (Shh) as a marker for polarizing region cells we have repeated the experiments of MacCabe et al. (1973) and Fallon and Crosby (1975) in an attempt to reexamine the question of a continuous role for the polarizing region during limb development. We report that the earlier experiments ...
Stringa E - - 1996
The embryonic skull bone, the calvarium, develops via intramembranous ossification, whereby mesenchymal cells differentiate directly into osteoblasts. However, under certain conditions, such as systemic calcium deficiency, regions of cartilage-like tissue are observed in the chick embryonic calvarium, suggesting the presence of pre-cartilage cells. We have recently identified and isolated a ...
Koide M - - 1996
The developing embryonic heart has been reported to contain significant levels of atrial natriuretic peptide (ANP). In this study, the role of ANP in cardiac development was evaluated using cultured cardiomyocytes isolated from chick embryos. We analyzed the effect of ANP on cell number, DNA synthesis, total RNA level, the ...
Zenjari C - - 1996
During regeneration, blastema cell proliferation depends on several different factors which are, as yet, not fully understood. Previous studies showing the presence of FGF-1 and FGF receptors in the limb blastema make FGF-1 a potentially important molecule for limb regeneration but they do not demonstrate that this factor is active ...
Huang M H - - 1996
We have identified a previously undescribed intrinsic cardiac adrenergic (ICA) cell type in rodent and human heart. Northern and Western blot analyses demonstrated that ICA cell isolates contain mRNA and protein of enzymes involved in catecholamine biosynthesis. Radioenzymatic catecholamine assays also revealed that the catecholamine profile of adult rat ICA ...
Catala M - - 1996
The spinal cord of thoracic, lumbar and caudal levels is derived from a region designated as the sinus rhomboidalis in the 6-somite-stage embryo. Using quail/chick grafts performed in ovo, we show the following. (1) The floor plate and notochord derive from a common population of cells, located in Hensen's node, ...
Szabat E - - 1996
HB-GAM (heparin-binding growth-associated molecule) is a secretory, extracellular matrix-associated protein that was isolated by screening for proteins that enhance neurite outgrowth in perinatal rat brain neurons. In the present study we have investigated the possible role of HB-GAM in cell proliferation in the developing rat limb. Exogenously added recombinant HB-GAM ...
Mescher A L - - 1996
Formation of a regeneration blastema on the amputated urodele limb involves changes in the gene activity of differentiated cells resulting in their histological dedifferentiation and their return to a proliferative state. This review summarizes studies in limb regeneration and in the related fields of tissue repair and limb development that ...
Stocum D L - - 1996
This review describes what we have learned about mechanisms of patterning in regenerating urodele limbs. Experimental evidence for three concepts is presented. First, the regeneration blastema is a self-organizing system based on positional memories inherited from parent limb cells. Second, the autonomous patterning mechanism involves local cell interactions that determine ...
Cohen-Gould L - - 1996
In gastrulation stage embryos of birds and mammals, the heart field is established as mesodermal crescents flanking the area rostrolateral to Hensen's node. Subsequent fusion of the bilateral heart primordia gives rise to a single tubular heart consisting of two epithelial layers: an outer myocardium and an inner endocardium. To ...
Webb S - - 1996
Murine trisomy 16 (Ts16) is a model for Down's syndrome and has close to a 100% incidence of atrioventricular septal defects (AVSDs). These have been proposed to result from abnormal development of the endocardial cushions, but the mechanisms are unknown. We aim to identify the initial defects in Ts16 hearts, ...
Fucci L - - 1996
The possibility that the minor embryonic chick hemoglobins might be present in a particular subgroup of primitive erythroid cells has been investigated by in situ hybridization. Probe to detect the mRNA for the alpha A globin chain of the minor embryonic hemoglobin was used, and the results of the hybridization ...
Wei X - - 1996
Caudal dysgenesis/sirenomelia is a malformation complex for which the pathogenesis is controversial. This report describes the particular vulnerability of specific caudal structures to Ochratoxin A (OA), a fungal toxin, as the basis for caudal dysgenesis in an avian model. The experimental procedure involved injection of 1 microgram of OA into ...
Maleski M P - - 1996
Cell condensations are the initial structures in the formation of proper cartilage and skeletal patterning in the developing vertebrate limb. Chondrogenic differentiation is dependent upon the cell-cell and/or cell-matrix interactions which take place during the condensation process. Coincident with the onset of condensation is the expression by limb mesenchyme of ...
Bellomo D - - 1996
During gastrulation, the node of the mammalian embryo appears to be an organising centre, homologous to Hensen's node in the chick and the dorsal lip of the amphibian blastopore. In addition, the node serves as a precursor population for the head process, notochord and foregut endoderm. We have studied node ...
Wilson V - - 1996
A prospective fate map of the late gastrulation mouse primitive streak has been charted in 8.5 dpc mouse embryos developed in culture, using the lineage marker DiI to label groups of cells. As at earlier stages, the fate of cells in the 8.5 dpc primitive streak is regionalised such that ...
Boskey A L - - 1996
It is a common belief that chondrocyte death must precede calcification in the growth plate. To challenge this dogma, cell devitalization was induced in an in vitro model that mimics in situ cartilage calcification. Chick limb-bud mesenchymal cells, plated in micromass culture, differentiate to form a cartilaginous matrix which mineralizes ...
Kanatsu M - - 1996
In murine embryogenesis, all cells that will constitute the embryonic structures originate from the epiblast (primitive ectoderm) tissue, the epithelial cell sheet of the gastrulating embryo. The cells of this tissue are totipotent at the beginning of gastrulation, but at the end of this period are specified to particular cell ...
Li S - - 1996
FGF-2 is proposed to be an important ectodermal signal directing limb outgrowth and patterning. Consistent with this hypothesis we show that ectopic application of FGF-2 can maintain the apical ectodermal ridge (AER)-dependent expression of Sonic hedgehog (Shh), and AER-dependent zone of polarizing activity (ZPA) signaling. We also find that ectopic ...
Selleck M A - - 1996
It is well established that Hensen's nodes can induce the formation of supernumerary digits after grafting into the anterior margin of the developing limb bud. The recent finding that distinct mesodermal cell populations are segregated within the node has made it possible to isolate different prospective cell types in an ...
Mérida-Velasco J A - - 1996
The parathyroid glands have been classically considered derivatives of the third and fourth pharyngeal pouches in most species, including humans. The presence of neural crest-derived cells in parathyroid glands connective tissue has apparently been established. However, our previous studies have provided a new hypothesis on the origin of these glands ...
Huang R - - 1996
We have studied the distribution of thoracic somite and somitocoele-derived cells using homotopical grafting between quail and chicken embryos and reincubation periods of 2-6 days. Serial sections were evaluated with antibodies against quail cells, quail hemangiopoietic cells and desmin. With the exception of neural crest cells in the cranial sclerotome ...
Akeo K - - 1996
The rod outer segments of the retina that are phagocytized by retinal pigment epithelial (RPE) cells are susceptible to lipid peroxidation because of their high content of polyunsaturated fatty acids. Linoleic hydroperoxides (LHP), synthesized by peroxidation of linoleic acids (LA), produce greater damage to retinal function than does LA. We ...
Yamamoto H - - 1996
To elucidate the degree of malignancy or the host-killing ability of rat ascites hepatoma AH66F, AH66 and AH130, the chick embryo-polymerase chain reaction system was used to measure the metastasis of these hepatoma cells. When inoculated into the chorioallantoic membrane vein of 10-day fertilized chicken eggs, AH66F cells metastasized in ...
Cruz Y P - - 1996
Allocation of cells in the marsupial epiblast to embryonic and extra-embryonic domains has to date been studied only histologically. An unresolved issue in marsupial embryology has been the existence of a medullary plate. We re-examined the hypotheses that the medullary plate, or neurectoderm, arises before notochord formation and that the ...
Halpern M E - - 1995
Zebrafish floating head mutant embryos lack notochord and develop somitic muscle in its place. This may result from incorrect specification of the notochord domain at gastrulation, or from respecification of notochord progenitors to form muscle. In genetic mosaics, floating head acts cell autonomously. Transplanted wild-type cells differentiate into notochord in ...
Prada F A - - 1995
Monoclonal antibody 3CB2 recognizes an antigen expressed in discrete cell types derived from ectoderm and mesoderm. Biochemical and immunohistochemical studies indicate that the antigen recognized by the antibody is a 55 kDa cytoplasmic protein that may be an intermediate filament associated protein (IFAP). Developmental studies show that 3CB2 antigen is ...
Yuan S - - 1995
The notochord normally arises from committed cells in the rostral tip of the primitive streak. After removal of these cells from the avian gastrula, embryos with notochords nevertheless develop in the majority of cases. A region required for the formation of this reconstituted notochord lies lateral to the primitive streak. ...
Borkowski O M - - 1995
We have used a novel cell marker, in which the twist promoter directs the synthesis of the cell surface protein CD2 (twi-CD2) to examine the development of the mesoderm in the Drosophila embryo after gastrulation and to locate the progenitor cell populations for different mesodermal derivatives. We find that the ...
Detrich H W HW - - 1995
Vertebrate hematopoietic stem cells are derived from vental mesoderm, which is postulated to migrate to both extra- and intraembryonic positions during gastrula and neurula stages. Extraembryonic migration has previously been documented, but the origin and migration of intraembryonic hematopoietic cells have not been visualized. The zebrafish and most other teleosts ...
Khaner O - - 1995
In the amniotes, two unique layers of cells, the epiblast and the hypoblast, constitute the embryo at the blastula stage. All the tissues of the adult will derive from the epiblast, whereas hypoblast cells will form extraembryonic yolk sac endoderm. During gastrulation, the endoderm and the mesoderm of the embryo ...
Willbold E - - 1995
Radial columnar organization of cell clones is a characteristic feature of vertebrate retinae that is structurally not understood. Here we provide in vitro evidence that Müller glia processes stabilize cells within columns. Dissociated embryonic chick retinal plus pigmented cells regenerate in vitro into fully laminated stratospheroids. After reaggregating chick and ...
Domingo C - - 1995
We show that notochord-inducing signals are present during Xenopus laevis gastrulation and that they are important for both inducing and organizing cell behavior and differentiation in the notochord. Previous work showed that convergent extension of prospective notochordal and somitic mesoderm occurs by mediolateral cell intercalation to produce a longer, narrower ...
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