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PubMed1990

Developmental change in the glycosaminoglycan composition of the chick embryo brain.

GAGs content was examined in chick embryo brain starting from the 9th day of incubation to the 4th post-hatching day. Chondroitin 6-sulfate, hyaluronate and heparan sulfate were recovered at any developmental stage examined. C6-S was the main GAG (except on the 15th day), while HS was the least represented. The highest differences in the relative amounts of GAGs are observed on the 9th day. C6-S shows high developmental relative changes, while HA and HS exhibit a similar pattern.

Animals↗

PubMed1983

Hemin inhibits transfer of pre-delta-aminolevulinate synthase into chick embryo liver mitochondria.

Pulse labelling studies in chick embryo livers show that hemin prevents the transfer of drug induced pre-delta-aminolevulinate synthase from the cytosol into the mitochondria, leading to an accumulation of precursor in the cytosol. No effect of hemin was observed on the transfer of pre-pyruvate carboxylase into mitochondria. These results eliminated a general toxic effect of hemin on mitochondrial import of proteins and are consistent with the view that hemin specifically inhibits the transfer of ALA synthase.

5-Aminolevulinate Synthetase↗

PubMed1986

Effect of simultaneous exposure to nickel chloride and benzo(a)pyrene on developing chick embryos.

In the present investigation the effect of Benzo(a)pyrene (BP) and Nickel chloride, quite often identified in crude and refined or waste oil, when injected in combination, was investigated on developing chick embryos after exposing them through yolk sac route on 6th day of incubation. Exposure to this combination in different doses resulted in no new deformities other than those experienced in BP treated chick embryos. The mortality and malformations experienced in the chick embryos exposed to BP alone and NiCl2 alone were seen to be added when both the chemicals were simultaneously inoculated into the same chick eggs.

Abnormalities, Drug-Induced↗

PubMed2006

Reclosure of surgically induced spinal open neural tube defects by the intraamniotic injection of human embryonic stem cells in chick embryos 24 hours after lesion induction.

OBJECT: The authors previously reported that human embryonic stem cells (hESCs) injected into the amniotic cavity of chick embryos immediately after neural tube incision in a surgically induced spinal open neural tube defect (ONTD) model promote the reclosure capacity of neural tubes. To simulate more closely the clinical situation of human ONTDs, in which a substantial time period elapses before the prenatal diagnosis of spinal ONTDs, the authors investigated whether this reclosure capacity remains enhanced by the intraamniotic injection of hESCs at 24 hours after ONTD induction. METHODS: One hundred twenty-two chick embryos with ONTDs were randomly assigned to two groups: the control group (59 embryos) and the hESC-injection group (hESC group, 63 embryos). After the neural tubes of both groups had been opened, the hESC group underwent direct intraamniotic injection with hESCs marked with an enhanced green fluorescent protein at 24 hours after ONTD induction. The lengths of the remnant ONTDs were measured and the presence of hESCs was determined at 4, 6, and 8 days after ONTD induction. No difference in survival rates was observed between the two groups. The mean length of the ONTDs, adjusted for body length at the time of death and initial lesion length, was significantly shorter in the hESC group than in the control group (p < 0.001). No hESCs were found within reclosed neural tubes; rather, they covered the defect area during the reclosure process. CONCLUSIONS: The authors demonstrate that hESCs injected into the amniotic cavity at 24 hours after ONTD induction enhance reclosure ability in chick embryos.

Amnion↗

PubMed1993

Primordial germ cells in the primitive streak stages chick embryo as studied by scanning electron microscopy.

Chick embryo primordial germ cells (PGCs) at stages 4-8 were localised in the late hypoblast layer. PAS staining confirmed their distribution in a large arc at the anterior border of the area pellucida/area opaca. By scanning electron microscopy the PGCs were seen as spherical cells within the late hypoblast layer. Individual cells separated from this layer and collected in groups of 2-10 in shallow pockets in the hypoblast layer prior to their migration. The pockets containing PGCs were clearly visible by light and scanning electron microscopy and demarcated the germinal ridge at stages 4-8.

Animals↗

PubMed1976

The influence of propanediol-1,3 on the development of the legs, wings and lower beak of the chick embryo.

In seven series of 31-34 chick embryos each, the influence of the position of the egg during incubation and of the administration of 0.05 ml propanediol-1,3 on the 5th day of incubation on the development and growth of the limbs and beak were studied. Isotonic saline injected embryos served as controls. The embryos were sacrificed at the age of 15 days. Incubation of the egg in a vertical position, with the air chamber pointing upward, proved to result in a slight, through significant reduction in the length of the limbs and beak. Propanediol was highly toxic if injected in the immediate vicinity of the embryo. If injected at some distance from the embryo, either into the air chamber or into the yolk, the agent proved to be teratogenic: measurements showed a considerable retardation of the longitudinal growth of the limbs and beak, the latter being a parrot beak in 60 per cent of the cases, whereas both the tibia and the metatarsals were, moreover, bent posteriorward. Histological studies of the tibia showed an underdevelopment of the periosteal bone collar and, at the angle of the bone, a replacement of the posterior part of this collar by endochondral bone trabeculae. The abnormalities observed are dissimilar to those demonstrated in hereditary congenital chondrodystrophy and in micromelic conditions induced by insulin or sulfonamides.

Animals↗

PubMed1976

Effects of cytochalasin B on the morphogenesis of explanted early chick embryos.

Effects of cytochalasin B (CB) on chick embryos explanted at stages 4-5 and cultured for 24 hours were studied. CB (2-4 mug/ml) inhibited blastodermal expansion and neural tube closure in over 90% of the embryos. Somite formation was inhibited only where neural tissue was very degenerate. The development of other structures was usually unaffected. Cellular degeneration occurred in severely affected neuroepithelium, but cells at various phases of mitosis were found throughout its thickness, suggesting that interkinetic nuclear migration had been inhibited. Electron microscopic studies of the flattened neural tube showed that CB disrupted microfilaments and reduced the number of cytoplasmic extensions, but had no apparent effect on microtubules and other organelles. These effects were reversible. Futhermore, dimethyl sulfoxide, at 0.2-0.4% (concentrations present in 2-4 mug/ml CB medium), had no adverse effect, indicating that the observed abnormalities were direct consequences of CB treatment.

Animals↗

PubMed1988

Histochemistry of mucosubstances in the gallbladder epithelium of the chick embryo.

Mucosubstances of epithelial cells of the chick embryo gallbladder were investigated by histochemical methods from days 12-21 of incubation (stages 38-46). On incubation day 14, only neutral mucins were detected; on day 15, neutral and sulfated mucosubstances were observed in the epithelial cells that invaginate the underlying mesenchyme. In the same sites, at day 16 of incubation, neutral, carboxylated and sulfated mucins were seen. From the 17th day of incubation until hatching, neutral, carboxylated and sulfated mucosubstances were present in the surface cells and in the cells lining the epithelial invaginations. During this period, the chemical characteristics of the secretory material are similar to those observed by Yamada and Hoshino (1972) in the fowl.

Animals↗

PubMed2000

Developmental changes in plasma catecholamine concentrations during normoxia and acute hypoxia in the chick embryo.

In the mammalian fetus, the cardiovascular responses to acute hypoxaemia include a redistribution of the cardiac output away from the periphery towards the adrenal, myocardial and cerebral circulations. A component of the peripheral vasoconstriction is mediated by increased release of catecholamines into the fetal circulation during acute hypoxaemia. Previously, we have shown that the chick embryo also shows an increase in peripheral vascular resistance during acute hypoxaemia and that this response becomes progressively larger towards the end of the incubation period. However, the ontogeny of the catecholaminergic response to acute hypoxaemia has not been investigated in this species. Fertilised chicken eggs were studied on days 10, 13, 16 and 19 of incubation (hatching is at 21 days). At each stage of incubation, blood samples were obtained from the chorioallantoic artery of the chick embryos during normoxia and after 5 min of hypoxaemia for measurement of plasma concentrations of adrenaline and noradrenaline by HPLC. Basal plasma adrenaline and noradrenaline concentrations by the end of the incubation period were much higher in the chick embryo than values reported for mammalian fetuses during late gestation. During normoxia, basal plasma noradrenaline concentration remained unchanged during development but plasma adrenaline concentration showed a developmental increase from < 25.1 pmol l-1 at day 10 to 3 nmol l-1 at day 19 of incubation. Acute hypoxaemia caused an increase in plasma noradrenaline and adrenaline from day 13 and day 16 of incubation, respectively. In addition, the increase in plasma adrenaline and noradrenaline and in the ratio of plasma adrenaline to noradrenaline during acute hypoxaemia became progressively larger by the end of the incubation period. These data show an ontogenic increase in basal plasma catecholamines and in the catecholaminergic response to acute hypoxaemia in the chick embryo during the last third of the incubation period.

Acute Disease↗

PubMed1982

Attachment, survival and neurite extension of chick embryo retinal neurons on various culture substrates.

Chick embryo retina neurons in culture extend neurites and form synapses. Seven different culture substrates were compared to determine which culture surface would produce the best neuronal survival and neurite extension. The order of survival of retina neurons during 7 days of culture is salt-precipitated collagen greater than ammoniated collagen greater than fibronectin greater than air-dried collagen = polylysine greater than tissue culture plastic greater than polyornithine. Similarly, salt-precipitated collagen allowed the greatest number of cells to extend neurites. The amount of neuronal aggregation and nonneuronal cell growth also varied with the substrate. Nonneuronal cell growth promoted neuronal growth and neurite extension on several substrates.

Animals↗

PubMedDate not supplied

Comparison of metastatic properties of a variety of mouse, rat, and human cells in assays in nude mice and chick embryos.

We have previously developed an assay to measure experimental metastatic ability of cells following intravenous injection into chorioallantoic membrane (CAM) veins of naturally immune deficient chick embryos. Here we compare metastatic properties of different cell types (ras-transformed and control NIH 3T3, LTA, and 10T1/2; melanoma; and glioma) from several species (mouse, rat, human), using chick embryos and the more commonly-used immune deficient host, nude mice. We found a good correlation between the two assays. Both hosts have advantages and disadvantages in assessing metastatic properties. We conclude that the chick embryo assay is a useful alternative host for experimental metastasis studies. This assay correlates well with and is less costly than assays using nude mice.

Animals↗

PubMed1969

The specificity of interferon induction in chick embryo cells by helical RNA.

Treatment of chick embryo cells growing in culture with rI:rC and many other RNA-like polymers results in the induction of interferon. DEAE dextran is required to facilitate the uptake of the RNA into the cells. Interferon-inducing activity is found with a variety of double-stranded helical polynucleotides, provided that all the sugar residues are ribose. However, the effectiveness of different active polynucleotides at a given concentration varies considerably. The differences in activity among the various polynucleotides do not appear to reflect differences in the rate or amount of uptake into the cells or in the rate of intracellular breakdown. Thehigh degree of specificity of the induction process is consistent with the existence of a specific intracellular receptor site, which may be a protein.

Animals↗

PubMed1997

Contribution of the primitive epicardium to the subepicardial mesenchyme in hamster and chick embryos.

A study about the hypothetical contribution of the epicardial cells to the subepicardial mesenchyme was carried out in Syrian hamster embryos of 9-12 days post coitum (dpc) and chick embryos of 3-5 days of incubation. In the epicardium and subepicardium of these embryos we have immunolocated the proteins cytokeratin (CK), vimentin (VIM), fibronectin (FN), and two antigens related to the transformation of endocardial cells into valvuloseptal mesenchyme, ES/130 and JB3. In the hamster embryos, CK+ subepicardial mesenchymal cells (SEMC) were apparently migrating from the primitive epicardium from 9.5 dpc at the atrioventricular (AV) groove and proximal outflow tract (OFT). The morphological signs of delamination extended by 11 dpc to the epicardium of the interventricular groove and the dorsal part of the ventricle. The relative abundance of the CK+ SEMC decreased in embryos of 12 dpc. VIM colocalized with CK in most SEMC, and in some epicardial mesothelial cells, mainly at the areas of delamination. CK immunoreactivity was also found in some early subepicardial capillaries. Similar observations were made in the chick embryos studied. The immunoreactive patterns obtained at the subepicardium with anti-FN, ES/130, and JB3 antibodies were similar to those reported in the areas of endothelial transformation of the endocardial cushions. We suggest that these observations are compatible with an epithelial-mesenchymal transformation involving the epicardial mesothelium and originating at least a part of the SEMC.

Animals↗

PubMed1997

Reduction in buoyancy alters parameters of motility in E9 chick embryos.

Over the course of embryonic development, chick embryos express 3 different types of motility (I, II, III). Although neural pattern generators appear to control embryonic motility, the mechanisms responsible for the sequential emergence and/or transformations in these behaviors are not known. Given the early presence of functional sensory connections and substantial changes in movement dynamics associated with body growth in the fixed volume of an egg, it was hypothesized that changes in environmental constraints might contribute to shaping the transformations in motility. In this study, we tested the hypothesis that changes in buoyancy can alter parameters of motility in ovo at embryonic Day 9 (E9). Results demonstrate that attributes of Type I motility can be altered by a reduction in buoyancy. The possible contributions of the environment and experience to transformations in embryonic motor behavior are discussed.

Animals↗

PubMed1986

Induction of porphyria in cultured chick-embryo hepatocytes by halogenated aromatic compounds.

Chick-embryo liver cells in culture were used to study the mechanism by which hexachlorobenzene (HCB) and other chlorobenzenes cause hepatic porphyria with accumulation of uroporphyrin (URO). The actions of the chlorobenzenes were similar to those of 3,4,3',4'-tetrachlorobiphenyl (TCB), but pretreatment with 3-methylcholanthrene (MC) or hexachlorobenzene was needed for maximum accumulation of URO. HCB was as potent and almost as rapid as the biphenyl in causing URO accumulation, but tetrachlorobenzenes caused little URO accumulation. Ellipticine, an inhibitor of cytochrome P-448, stopped the accumulation of URO. A mechanism is proposed for the action of the chlorobenzenes that involves binding to cytochrome P-448 and production of active oxygen species that oxidize uroporphyrinogen.

Animals↗

PubMed2001

BMP4 plays a key role in left-right patterning in chick embryos by maintaining Sonic Hedgehog asymmetry.

In chick embryos, the first signs of left-right asymmetry are detected in Hensen's node, essentially by left-sided Sonic Hedgehog (Shh) expression. After a gap of several hours, SHH induces polarized gene activities in the left paraxial mesoderm. We show that during this time period, BMP4 signaling is necessary and sufficient to maintain Shh asymmetry within the node. SHH and BMP4 proteins negatively regulate each other's transcription, resulting in a strict complementarity between these two gene patterns on each side of the node. Noggin, present in the midline at this stage, limits BMP4 spreading. Moreover, BMP4 is downstream to Activin signals and controls Fgf8. Thus, early BMP4 signaling coordinates left and right pathways in Hensen's node.

Activins↗

PubMed1975

The development of the circulating blood volume of the chick embryo.

The circulating blood volume of the chick embryo was determined from the 4th up to the 18th day of hatching. In contrast to former studies, there was employed a radioisotope dilution method with albumin-bound I131. The findings are in close correspondence to those of the earlier studies. The blood volume does not display an entirely perfect curve of exponential growth, i.e., the doubling time increases steadily. The blood volume attains a peak value between the 16th and 18th day and decreases somewhat toward the end of the hatching period. There has been postulated a reduction of total red cell volume and hemoglobin caused by the involution of the extraembryonic circulatory system. The destruction of the erythrocytes seems to take place in the endodermal epithelium of the proximal yolk sac, where an accumulation of iron could be demonstrated on the 19th and 20th days.

Animals↗

PubMed1979

The mechanism of somite segmentation in the chick embryo.

The segmentation of somites in the chick embryo has been studied by transmission and scanning electron microscopy (stages 8-14). The segmental plate mesoderm consists of loosely arranged mesenchymal cells, whereas the newly formed somites are composed of elongated, spindle-shaped cells arranged radially around a lumen, the myocoele. The diamter of each somite is thus two cells plus the myocoele. Two major factors appear to be responsible for the change in cell shape at segmentation: (1) Each prospective somite cell becomes anchored at one end to the adjacent epithelia (i.e. the neural tube, the notochord, the ectoderm, the endoderm or the aorta) by means of collagen fibrils. These fibrils are already present in the segmental plate before the somites begin to form. (2) A change in cell-to-cell adhesiveness causes the free ends of these cells to adhere to one another. (Bellairs, Curtis & Sanders, 1978). This adhesion is then supplemented by the development of tight junctions proximally in the somite. Because it is anchored at both ends, each somite cell is under tension in much the same way as a fibroblast cell in tissue culture is under tension. Each somite cell therefore becomes elongated and the somite as a whole accommodates its general shape to that of the space available between the adjacent tissues. The arrangement of the cells in the more differentiated somites (stages 17-18) has also been examined and it has been found that the chick resembles Xenopus in that the myotome cells undergo rotation and become orientated in an anteroposterior direction.

Animals↗