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At least 973 records · Page 54Linked to original sources

PubMed1990

Behaviour of chick embryo aortic cells obtained through nonenzymatic means cultured onto collagen gels.

In the present paper we used a method whereby some of the cellular events that take place in the aortic wall during chick embryo development can be studied in vitro. Collagen gels were utilized to culture endothelial cells obtained through nonenzymatic means from aortic explants isolated from 12- to 14-day-old chick embryos. These cells were characterized by morphological and immunocytochemical criteria. After 72 h, explanted endothelial cells from embryonic aorta formed a monolayer of polygonal cells, which gave rise to elongated cells that migrate into the collagen gel. These cells are similar to those of mesenchyme-like cells observed in vivo at the subendothelial region of 14-day-old chick embryonic aorta. In long-term cultures, some of these cells acquired features either of synthetic smooth muscle cell phenotype, or of fibroblast-like cells very similar to those found in developing aorta. These results indicate that the culture of explants of chick embryo aorta on three-dimensional collagen gel is a valuable system for studying some of the complex morphogenetic events that occur during the development of the aorta.

Animals↗

PubMed1982

Serum factors affecting transdifferentiation in chick embryo neuro-retinal cultures.

Adult sera (horse, chicken and newborn bovine serum) do not support extensive transdifferentiation of lens cells in cultures of 9-day chick embryo neural retina. Conversely, both chick embryo extract and foetal calf serum promote the accumulation of delta-crystallin (a marker for lens cells) in such cultures. Dialysed foetal calf serum does not allow transdifferentiation into lens, whereas the dialysis medium is able to do so in the absence of macromolecular serum components, suggesting one or more active factors of low molecular weight. Choline acetyltransferase activity (cholinergic neuronal marker) is generally maintained for longer under conditions which do not permit extensive transdifferentiation. Glutamine synthetase activity (a glial marker) is inducible by hydrocortisone in dense neuro-retinal cultures, and this hormone also reduces the extent of later lens development.

Animals↗

PubMed2005

Cardiopulmonary effects of chronic administration of the NO synthase inhibitor L-NAME in the chick embryo.

BACKGROUND: Experimental observations in mammalian models suggest that endothelial nitric oxide (NO) synthase (NOS) content and activity are decreased in persistent pulmonary hypertension of the newborn. OBJECTIVES: To test the hypothesis that disruption of NO signaling in the developing chick embryo lung may contribute to pulmonary hypertension. METHODS: We analyzed pulmonary arterial reactivity and structure and heart morphology of 19-day chick embryos (incubation time 21 days) that received a daily injection of the NOS inhibitor Nomega-nitro-L-arginine methyl ester (L-NAME, 20 mug per gram egg) or vehicle from day 12 until day 18. RESULTS: Exposure to L-NAME did not affect embryonic survival or body mass of the embryos. The contractile responses to KCl, endothelin-1, the thromboxane A2 mimetic U46619, noradrenaline, and electrical-field stimulation were not affected by exposure to L-NAME. In contrast, in ovo L-NAME exposure reduced the sensitivity of pulmonary arteries to acetylcholine (pD2: 6.53 +/- 0.14 vs. 6.96 +/- 0.13; p < 0.05) and this effect was reversed by the NOS substrate L-arginine. Relaxations induced by sodium nitroprusside or forskolin were not altered by chronic L-NAME. Pulmonary vessel density was not different, but the percentage medial wall area of small pulmonary arteries (external diameter 10-50 microm) was slightly but significantly increased in the embryos exposed to L-NAME. In addition, hearts of L-NAME-exposed embryos showed an increase in right and left ventricular wall area. CONCLUSIONS: Chronic inhibition of NOS produced, in the chick embryo, impairment of endothelium-dependent relaxation, structural remodeling of the pulmonary vascular bed and biventricular cardiac enlargement.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗

PubMed1987

Patterns of oxygen consumption during establishment of cephalocaudal polarity in the early chick embryo.

Oxygen uptake was studied during the establishment of cephalocaudal polarity in the very early chick embryo, i.e., 10 hr before (stage VI) and at laying (stage X). Oxygen fluxes in minute regions of the intact blastoderms were measured in vitro by scanning microspectrophotometry in the presence or absence of glucose. The oxygen consumption of the whole blastoderm remained constant (6 nmol O2 X hr-1) throughout the period studied, although the number of cells increased more than twofold. The regional oxygen fluxes varied from 0.41 to 1.13 nmol O2 X hr-1 X mm-2 at stage VI and from 0.42 to 0.70 nmol O2 X hr-1 X mm-2 at stage X. At stage VI, the oxygen flux in the center of the blastoderm was significantly higher than that in its periphery. This pattern remained evident when the values were corrected for cell number or for cytoplasmic volume. At stage X, there was a tendency for the oxygen fluxes to decrease from the posterior to the anterior regions of the area pellucida. Thus the pattern of oxidative metabolism in the late uterine embryos seems to change from radial to bilateral. This change of symmetry probably reflects the process of formation of the embryonic axis. In addition, the fact that the oxygen uptake was similar in the presence or absence of glucose suggests that early chick embryos metabolize essentially intracellular stores.

Analysis of Variance↗

PubMed1992

[Distribution of type IV collagen, laminin and fibronectin during naris formation in the chick embryo].

The presence and distribution of extracellular matrix (ECM) macromolecules were analyzed in the facial primordia of chick embryos from stages (22-28) of development corresponding to naris formation. Frozen sections through the nasal placode, medial nasal processes and lateral nasal processes were prepared for indirect immunofluorescence employing a biotin-avidin DCS system using monoclonal antibodies against type IV collagen, laminin and fibronectin. The results demonstrated that ECM played a very important role in regulating migration, adhesion and anchorage of cells during morphogenesis. Strong fluorescence of basal lamina was present in the areas of rapid ingrowth of the nasal placode. It was suggested that ECM has very important guiding and regulating role during naris formation in chick embryo.

Animals↗

PubMed1995

[Embryotoxic effects of a combination of zearalenone and vomitoxin (4-dioxynivalenole) on the chick embryo].

Mycotoxins zearalenone and vomitoxin (4-deoxynivalenol) are often joint contaminants of grains infested by micromycetes of the genus Fusarium. Toxic effects of both mycotoxins on experimental organisms and farm animals are well known, but we have not found any literary reference to toxic effects of the combination zearalenone and vomitoxin. Embryotoxic effects of zearalenone, vomitoxin and combinations of various doses of zearalenone with constant addition of vomitoxin were studied in a three-day chick embryo. The objective of the study was to determine the coaction of vomitoxin on zearalenone embryotoxicity. Thermostat-incubated fertile eggs of White Leghorn hens were candled after three-day incubation, the shell above the embryo was removed, and within the embryotoxicity range zearalenone, vomitoxin and various doses of zearalenone with constant addition of 2 micrograms vomitoxin were applied to morphologically normal embryos. The groups of ten embryos were applied mycotoxins and their combinations in 10 microliters of their solutions to amnions using a special glass micropipette. Control group comprised twenty embryos which were applied 10 microliters of solvents used, 1% NaHCO3 and 10% ethanol. The eggs were covered with glass plates and their incubation was going on until the eighth day of their development. The embryos that died during incubation were discarded. On the eighth day of development, surviving embryos were taken out from the eggs and malformations of head, orofacial region, body wall, limbs and heart were determined microscopically. Tab. I shows total numbers of dead and malformed embryos after application of the particular doses of zearalenone, vomitoxin, their combinations and control solvents. The embryotoxicity range started at a dose of 5 to 20 micrograms per embryo. Zearalanone did not have any teratogenic effects on chick embryos. Applications of high doses of zearalenone (100 and 30 micrograms) instantly caused arrhythmia, atrio-ventricular dissociation or even heart stoppage. The beginning of the embryotoxicity range for vomitoxin was found to be within the narrow range of 1 to 3 micrograms per embryo. Among malformations, only a defect of the interventricular septum of the heart was found in 4% of the cases. The combined embryotoxic effects of zearalenone and vomitoxin were of additive, and mostly embryolethal nature. Among the malformations searched for, only 5% of the embryos exhibited a defect of the interventricular septum of the heart. Due to the good prediction fitness of chick embryo that has been proved by estimates of mycotoxin toxicity to mammals it is possible to suppose that toxic effects of the frequently occurring combinations of zearalenone and vomitoxin in fusarium-infected feeds will also be of additive nature for farm animals.

Abnormalities, Drug-Induced↗

PubMed1990

The development of the chick embryo gallbladder studied by scanning electron microscope.

The differentiation of the gallbladder mucous membrane in chick embryos has been studied from the 11th day of incubation until hatching (stages 37-46 of Hamburger an Hamilton 1951) with scanning electron microscope. The surface of the mucous membrane, at the 11th day of incubation, appears regularly smooth. From the 12th day onwards, longitudinal folds appear on the surface of the mucous membrane, becoming more and more numerous and complicated in the following days. During the last days of incubation, branching and anastomosing folds are present. At the 11th day of incubation, the epithelial cells lining the gallbladder surface have flattened apices, with short microvilli. From the 12th day onwards, the epithelial cells show dome shaped apices, with long numerous microvilli. From the 15th day of incubation onwards, some particular secretory cells can be detected. The appearance of these cells is probably related to the water-absorbing function of the gallbladder which in the last days of incubation completes its functional development, because of precise digestive requirements of the chick embryo.

Animals↗

PubMed1997

Laminin immunoreactivity in enteric ganglia of the chick embryo.

The localization and time of appearance of laminin in the duodenum of the chick embryo were studied with an anti-laminin polyclonal antibody and immunofluorescence. Laminin immunoreactivity was observed in the basement membranes of the mesothelium, mucosal epithelium, muscle cells and in the adventitia and basal surface of the endothelium in blood vessels. In addition, laminin immunostaining was detected over the contour of myenteric ganglia from embryonic day 7 and inside these ganglia from embryonic day 13. In colocalization experiments, laminin immunoreactivity occurred outside tubulin immunoreactive neuronal cell bodies, thus indicating that it resides in glial cells or in extracellular spaces. In addition connecting strands of the myenteric plexus and intramuscular nerves expressed laminin immunoreactivity. Similar observations were made in the proventriculus, gizzard, ileum and rectum of chick embryos, and in the duodenum and rectum of quail embryos. In the ganglion of Remak, laminin immunofluorescence was detected in the collagenous sheath that surrounds the ganglion and inside the ganglion, where it outlines neuronal cell bodies. Laminin immunoreactivity within the myenteric ganglia during the 3rd week in ovo, appears to be characteristic of the avian species examined, since it was not observed in the rat and mouse intestine at equivalent developmental stages. Immunocytochemical experiments at the electron-microscope level confirmed that structures with laminin or laminin-like immunoreactivity occur both around and inside myenteric ganglia. It is suggested that laminin, or an immunologically similar molecule, may play a role in the development and maturation of avian enteric ganglia.

Animals↗

PubMed1995

The role of extracardiac factors in normal and abnormal development of the chick embryo heart: cranial flexure and ventral thoracic wall.

The present study was designed to investigate whether the formation of the cranial flexure is involved in the normal positional changes of the embryonic heart tube that occur during its transformation from the c- to s-shaped loop. For this purpose, the formation of the cranial flexure was locally suppressed in chick embryos by introducing a straight hair into the neural canal. In the experimental embryos, prevention of cranial flexure did not suppress the normal positional changes of the heart tube. However, other anomalies in the looping of the heart tube were frequently observed. These anomalies were caused by alterations in the formation of the ventral thoracic wall, which in turn seemed to be related not to the prevention of the cranial flexure but rather to accidental injuries during the implantation of the hair. In the embryos with abnormal looping of the heart tube, the incidence of delayed/defective septation of the heart was significantly higher than in embryos with normal looping. These results show that in the chick embryo: (1) cranial flexure is not involved in normal positional changes of the heart loop; (2) manipulations at the head region of the embryo can unintentionally result in developmental disorders of the ventral thoracic wall; (3) such disorders can result in congenital heart defects through mechanical interference with normal looping of the embryonic heart. The possible significance of these findings for the evaluation of experimental studies of chick embryos is discussed in the context of anomalies observed after surgical ablation of the premigratory cranial neural crest.

Animals↗

PubMed1982

Purification and properties of magnesium- and manganese-dependent ribonucleases H from chick embryo.

Two RNases H, Mg2+- and Mn2+-dependent RNases H, are present in extracts of chick embryo. These RNases H can be separated by phosphocellulose column chromatography. Mg2+-dependent RNase H was purified over 900-fold and Mn2+-dependent RNase H over 1,700-fold from chick embryo extracts. The molecular weight of the purified Mg2+-dependent RNase H was about 40,000 and of the Mn2+-dependent RNase H about 120,000, when estimated by gel filtration. Mg2+-dependent RNase H exhibits maximal activity at pH 9.5, and requires 15 to 20 mM Mg2+ for maximal activity, whereas Mn2+-dependent RNase H is most active at pH 8.5, and is maximally active at the concentration of 0.4 mM Mn2+, and has some activity with Mg2+. Both enzymes require a sulfhydryl reagent for maximal activity. Mn2+-dependent RNase H was inhibited by o-phenanthroline, pyrophosphate, and those polyamines tested, whereas Mg2+-dependent enzyme was not, although it was inhibited by NaF. Both RNases H liberate a mixture of oligonucleotides with 5'-phosphate and 3'-hydroxyl termini endonucleolytically.

Ammonium Sulfate↗

PubMed1995

Maturation of cerebellar granule cells is delayed in cultures derived from ethanol-treated chick embryos: survival and proliferation studies.

Previous studies from this laboratory have shown that ethanol administration to chick embryos during embryonic days 1-3, a critical period of neuroembryogenesis, differentially affects primordial CNS structures. In this study, chick embryos were treated in ovo with ethanol (10 mg/50 microliter/day) at E1 to E3. At 14 days of embryonic age cerebellar (E14CE) granule cell cultures were prepared from both control and ethanol-treated embryos. Growth patterns were evaluated morphologically and the neuronal nature of these cultures was evaluated immunocytochemically. E14CE granule cell cultures exhibited neurofilament immunoreactivity demonstrating the neuronal-nature of these cultures. In addition E14CE granule cultures contained numerous glutamatergic neurons as assessed by positive glutamate immunoreactivity and also some GABAergic neurons as assessed by positive GABA immunoreactivity. Cultures derived from both control and ethanol-treated embryos were labeled with 3H-thymidine and assessed for effects on survival and proliferation in culture. Cultures derived from ethanol-treated embryos showed a higher rate of proliferation and survival during the first 3 days in culture as compared to those derived from controls. However, after 3 days in culture, survival was lower in the cultures from ethanol-treated embryos as compared to those derived from controls. We interpret these findings to mean that (a) ethanol arrested cerebellar granule cell development at an immature state; (b) immature neurons have a higher survival capacity than differentiated neurons; and (c) ethanol accelerates normal neuronal cell death as previously reported.

Animals↗

PubMed1983

Chick embryo spinal cord neurons synthesize a transferrin-like myotrophic protein.

Highly enriched cultures of chick embryo spinal cord neurons synthesize and secrete a protein which is immunoprecipitable by anti-ovotransferrin. Ovotransferrin, an iron-binding glycoprotein of Mr 80 000, is also shown to stimulate in vitro myogenesis of cultured chick embryo myotubes as measured by saturable dose-dependent increase in acetylcholine receptors. This effect is probably dependent on ovotransferrin's ability to donate iron to the cells. In many respects ovotransferrin is similar to 'sciatin', a myotrophic protein isolated from chicken sciatic nerves.

Animals↗

PubMed1993

Modulation of tensin and vimentin expression in chick embryo developing cartilage and cultured differentiating chondrocytes.

It has been proposed that tensin, in association with several other proteins, mediates the micro-filament-integrin link. Here we describe the isolation of clones spanning about 5 kb from the 3' end of tensin mRNA from cultured chick embryo chondrocyte and embryonic heart cDNA libraries. Tensin expression was investigated in cultured chick embryo cells. It was observed that tensin expression is dependent upon substrate adhesion and it is turned off after 7 days of suspension culture. This process is reversible. Tensin expression is also regulated during cartilage cell differentiation in vivo; at Hamburger and Hamilton stage 39-40, non-hypertrophic tibial chondrocytes express both RNA and protein while hypertrophic chondrocytes do not. In the culture system the expression of vimentin, a major component of intermediate filaments, showed an opposite behaviour since the suspension culture enhances the accumulation of both vimentin and its mRNAs. Therefore in chick embryo cultured chondrocytes and in vivo, during cartilage development, cell shape changes and/or integrin-extracellular matrix protein interactions may be involved in the regulation of these two genes coding for cytoskeletal proteins.

Amino Acid Sequence↗

PubMed1982

Endoderm/mesoderm multiplication rates in stage 5-12 chick embryos.

Multiplication rates for the endoderm/mesoderm layer of the head-process to 17-somite-stage chick embryo were studied by implanting essentially identical transplants labeled with tritiated thymidine into paired recipient embryos. One recipient was fixed as soon as the transplant had healed (after 30 min) and the other was reincubated an additional 3.5 to 22.5 hr; the ratios of labeled cells in the paired embryos provided points on a graph that indicated that doubling of endoderm/mesoderm cells in head-process-stage chick embryos occurs at approximately 4.0 and 17.2 hr of reincubation.

Animals↗

PubMed1993

A test for teratological effects of power frequency magnetic fields on chick embryos.

An analysis of 13 studies of the teratological effects of pulsed magnetic fields on chick embryos from ten independent laboratories permits no clear conclusions. Comparatively little has been done to follow up on the reports by Juutilainen and coworkers on the effects of extremely low-frequency, sinusoidal magnetic fields on the malformation rate in chick embryos. Our attempt to follow up on their results using similar but not identical exposures of 10 microT, 50 Hz magnetic fields produced negative results.

Animals↗

PubMed1994

5-Azacytidine changes gene expression and causes developmental arrest of early chick embryo.

Methylation of DNA appears to be an important maintenance mechanism for inhibiting gene expression during development in vertebrates. 5-azacytidine (5-azaC) is used as an experimental tool for demethylation and it induces differentiation in various systems. In the chick embryo, the first cellular migrations signal the onset of primitive streak and gastrula formation and result in neural induction and morphogenesis of the embryonic axis. In the present work with the early chick embryo, 5-azaC perturbs normal cellular migrations and the embryos produce an atypical short, thickened primitive streak. These embryos have the tendency to form neural tissue but the embryonic axis shows sparse identity of patterning along its length. A small percentage of embryos display formation of double embryonic axes. Blastula embryos show reduced expression of some polypeptides and express characteristic polypeptides which are not present in morula embryos normally. Under the influence of 5-azaC, blastula embryos expressed all the polypeptides which are characteristic of embryos at both the morula and the blastula stages. If 5-azaC perturbs DNA methylation as the chick embryo develops from the histologically simple blastula, then the wave of methylation which has been reported to start at the late blastula and continues during postgastrulation in vertebrate embryos does not seem to be important for the induction of mesodermal and of neural tissues, but is important for the patterning of these tissues.

Animals↗

PubMed1991

Effect of aciclovir on the development of the chick embryo in ovo.

The effect of aciclovir (ACV) on embryonic development was investigated using the chick embryo in ovo and treatment during organogenesis. ACV 30-1000 micrograms was applied as single doses prior to or after 24 h of incubation into the yolk sac, and ACV 3-100 micrograms after 2, 3 or 4 days of incubation (DI) directly to the embryo. Data were evaluated after a total of 8 days of incubation. (1) A dose-related increase in the rate of abnormal development was found in the surviving embryos. Depending on the route of drug administration a dose of 300, respectively, 5 micrograms ACV/egg had to be applied to induce 50% abnormal development. (2) Gross structural abnormalities of the surviving embryos mainly concerned the beak and the extremities. With the experimental set-up used a different pattern of abnormalities in the survivors after treatment at various stages could not be observed. The results are compared with data obtained with ACV in rodents in our laboratory. It is suggested that chick embryos are also capable of converting ACV into its triphosphate to interfere with DNA metabolism, probably through a chain break mechanism.

Abnormalities, Drug-Induced↗

PubMed1978

Substance P-like immunoreactivity in cultured spinal ganglia from chick embryos.

The localization of substance P (SP) or a SP-like peptide in cultured ganglia from chick embryos was studied by the indirect immunofluorescence technique. Ganglia from 8-16 days old chick embryos and from newly hatched chickens were cultured in a control medium or in the presence of nerve growth factor (NGF). Addition of colchicine and exposure to different explanted peripheral tissues were also tried. Ganglia from the younger embryos (8-12 days) cultured for 24 h with added NGF showed a weak SP-like immunoreactivity (SPLI) in some cell bodies and strong specific immunofluorescence in nerve fibres growing out from the ganglia. In spinal ganglia of the older embryos (14 and 16 days) and newly hatched chickens cultured with and without NGF the concentration of SPLI in the cell bodies was considerably higher. Addition of colchicine to spinal ganglia cultured 12 h in NGF-medium, resulted in retraction of nerve fibres and strongly fluorescent, expanded nerve fibres were observed in peripheral parts of the ganglia. Explants of skin placed near the spinal ganglia stimulated the outgrowth of fibres, some of them containing SPLI. A few fluorescent fibres were also seen within the skin explants. Also heart tissue explants stimulated outgrowth of nerve fibres, but innervation of these explants with SPLI-containing nerves could not be observed. Nerve fibre-extension from the spinal ganglia was not stimulated by spinal cord explants. The present results support the existence of SP-containing primary sensory neurons in chickens.

Age Factors↗