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At least 127 records · Page 7Linked to original sources
PubMed1987

Ethanol treatment inhibits mesoderm cell spreading in the gastrulating chick embryo.

Gastrulating chick embryos in culture were treated with ethanol solutions, following which the mesoderm cells migrating from the primitive streak were examined by scanning electron microscopy. Morphometric analysis of cell shape showed that mesoderm cells from treated embryos were significantly more rounded and therefore less well spread than controls, and showed fewer filopodial contacts with the overlying basement membrane. This result was only obtainable for cells leading the migration from the primitive streak, since the following cells in the mesodermal mass apparently did not show this difference. The ethanol concentration required to obtain a reliable effect was 5%, while lower concentrations produced highly variable results. The mesoderm cells were also examined for their in vitro responsiveness to ethanol by investigating their adhesiveness and cytoskeleton. No effect was observed on cell-glass adhesion as judged by interference reflection microscopy using up to 1% ethanol. This concentration did, however, disrupt the actin cytoskeleton of cultured cells when stained with NBD-phallacidin, but lower concentrations were ineffective. It is concluded that ethanol treatment of cultured embryos has a significant effect on the substratum relationships of some migrating mesoderm cells.

Animals↗
PubMed1980

Microvillous membrane vesicle accumulation in media during culture of intestine of chick embryo.

Explanting chick embryo duodenal tissue elicits an increase in the activities of alkaline phosphatase and maltase, an effect which is greatly enhanced by the addition of thyroxine. A large part of the elevated enzyme activity is released into the culture medium, from which it can be sedimented by centrifugation at 200 000 X g. The resulting pellet contains 87% or more of the alkaline phosphatase and maltase activity present in the medium at the end of 72 h of culture, but only about 25% of the protein. Negative staining of the pellet reveals the presence of microvesicles, the surfaces of which bear tiny protrusions resembling the knobs that have been seen on isolated microvilli and in preparations of purified microvillous membrane. The microvesicles appear to be derived from fragmentation of microvilli. Microvesicles with similar properties can be washed out of the duodenal lumen of embryos near hatching, suggesting that vesiculation may be a normal process that plays a useful role in intestinal function.

Alkaline Phosphatase↗
PubMed1986

The action of various vitamin D3 metabolites on calcium and phosphorus metabolism in chick embryo calvariae.

Chick embryos from vitamin D-deficient hens given physiological doses of 1,25-dihydroxyvitamin D3 or 24,25-dihydroxyvitamin D3 or both become severely hypocalcemic, hyperphosphatemic and fail to hatch as compared to those derived from hens given 25-hydroxyvitamin D3 or 24,25-difluoro-25-hydroxyvitamin D3. Calvariae from the former contain less mineral and on incubation in vitro produce significantly lower calcium and higher phosphate concentration in the medium than do the calvariae derived from the embryos of hens supported on 25-hydroxyvitamin D3 or 24,24-difluoro-25-hydroxyvitamin D3.

24,25-Dihydroxyvitamin D 3↗
PubMed1975

[Induced degeneration and lysosome activity in the cells of the tail bud in the early chick embryo].

In chick embryos, cells of the tail bud are induced to degenerate by autophagocytosis when treated by puromycine or sodium fluoride. Although these degenerative processes exhibit some differences, according to the nature of the inhibitor used, their initial steps, which consist in a modification of the Golgi zone, are identical. These facts are discussed in relation to the problem of morphogenetic cell degeneration.

Animals↗
PubMed1981

Elimination of polyneuronal innervation in proximal and distal leg muscles of chick embryos.

In chick embryo leg muscles, elimination of polyneuronal innervation takes place one to 1.5 days earlier in the thigh muscle m. ambiens than in the foot muscle m. flexor hallucis brevis. Initial formation of synapses takes place 2-3 days earlier in the proximal than the distal muscle, so the length of time synapses have been active may be a factor in the control of elimination of polyneuronal innervation during development.

Animals↗
PubMed1987

Myoblast differentiation is induced by nerve transplanted to chick embryo legs.

Chick embryos were denervated early in development in order to disrupt the normal inductive interactions between the nervous system and developing populations of mononucleated myoblasts and their precursors in the leg. Neural tissue, either spinal cord or ciliary ganglion, was transplanted to one leg of the denervated embryos; the other leg remained aneural. Clonal analysis of cell populations in the transplant-containing legs showed that ectopic nerve tissue can recapitulate some of the neuromuscular interactions that occur in normally developing embryos. Chief among these was the observation that transplantation induced the appearance of the CMR-III myoblast class in the leg muscle. Since the process by which CMR-III myoblasts are produced from a precursor is dependent on nerve both in vivo and in vitro (Bonner, P.H. and T.R. Adams, Dev. Biol., 90:175-184, 1982), it was concluded that transplanted nerve tissue can also induce myoblast differentiation.

Animals↗
PubMed1985

Nerve growth factor treatment does not prevent dorsal root ganglion cell death induced by target removal in chick embryos.

In chick embryos, on the 3rd day of incubation, the developing right wing bud was removed. One group of the operated embryos was treated with a daily dose of 20 micrograms purified nerve growth factor (NGF) from the 5th day of incubation and sacrificed on the 12th day. The other group was sacrificed on the 12th day of incubation and served as control. NGF was also administered to intact, unoperated embryos for comparison. The size of the dorsal root ganglia in segments 13-16 innervating the wings, were estimated and the number of surviving dorsal root ganglion cells counted both on the right (operated) and left (intact) sides. Although NGF brought about an increase in the size of the ganglia and an increase in the number of dorsal root ganglion cells bilaterally, it was not able to prevent excessive cell death of dorsal root ganglion cells on the operated side. The number of surviving neurons in the dorsal root ganglia on the operated side in embryos with or without NGF administration was only about 30-50% of the number of the intact side. These results show that cell death induced by target removal cannot be offset by NGF administration. It is concluded that NGF may act as a growth promoting agent for developing sensory neurons but other peripheral trophic factor/s are also needed for the maintenance and survival of dorsal root ganglion cells.

Animals↗
PubMed1984

Motor innervation of proximally rotated chick embryo wings.

Chick embryo wing buds were rotated close to the lateral edge of the somites at stage 19, prior to limb innervation. Despite the abnormal orientation of the resulting limb, the motor pools to biceps and triceps were largely normal, as judged by electrical stimulation and horseradish peroxidase labelling just prior to hatching. The only abnormalities were a few caudal motoneurons innervating biceps and a few rostral motoneurons innervating triceps. This distribution is similar to that seen normally in young embryos before the completion of motoneurons death and it is suggested that the rotation may be keeping alive motoneurons which otherwise would die. The morphology of the brachial plexus supplying rotated wings was abnormal. It is concluded that axons growing into the limb bud from the spinal cord can compensate for reversal of both the limb axes and selectively innervate appropriate muscles. The result is consistent with others in which proximal reversal of one limb axis alone produced normal innervation.

Animals↗
PubMed1978

Morphological and biochemical differentiation in RSV transformed chick embryo myoblasts.

Chick embryo myoblasts have been transformed with a temperature sensitive mutant of Rous Sarcoma virus (RSV ts68). At permissive temperature (36 degrees C) it is shown that transformed myoblasts have lost their ability to form myotubes as well as to express the biochemical markers of myogenic differentiation. Upon a shift to the non-permissive temperature (41 degrees C), the normal program of differentiation is restored; myotubes are formed which express muscle specific proteins.

Acetylcholine↗
PubMed1982

Thermal inhibition of repair of methylmethane sulfonate-damaged DNA in chick embryo fibroblasts.

Chick embryo fibroblasts were treated with the monofunctional alkylating agent methylmethane sulfonate at various concentrations for 1 h at 42 degrees C, rinsed and then incubated post-treatment at various temperatures at which the kinetics of alkali-labile bond disappearance was followed. Growth experiments showed that these cells grew similarly at temperatures of either 37 degrees C or 42 degrees C. Repair as assessed by removal of alkali-labile bond was also similar for postincubation in the temperature range 37-42 degrees C for damage due to methylmethane sulfonate treatment at concentrations less than 1.5 mM. When the postincubation temperature was raised higher than 42.5-43 degrees C, this type of repair was stopped. The normal internal body temperature of adult chickens is about 41.6 degrees C. Hence the present finding indicates that chick cells are much more severely restricted in DNA repair at temperatures above normal than are mammalian cells, which can function in this respect for several deg. C above 37 degrees C.

Animals↗
PubMed2002

Photodynamic parameters in the chick chorioallantoic membrane (CAM) bioassay for photosensitizers administered intraperitoneally (IP) into the chick embryo.

The chick chorioallantoic membrane (CAM) assay was used to determine the photodynamic response (PDR) of blood vessels to Photofrin, 5-aminolevulinic acid (ALA), benzoporphyrin derivative monoacid ring A (BPD-MA) and lutetium texaphyrin (Lutex). The photosensitizers were administered systemically via intraperitoneal injection into the chick embryo. Forward stepwise regression analysis of the PDR results enabled the individual contributions of seven experimental variables to be ranked: drug dose, light dose, fluence rate, drug uptake time, vessel type (whether arterioles or venules), vessel diameter, and embryo age. The order of importance of the variables, the PDR profile, was determined for each photosensitizer. Relative contributions of the experimental variables from this study to the CAM PDR were compared with those from our previous study on PDR of CAM blood vessels following topical application of the same photosensitizers. PDR profiles were interpreted in terms of biophysical and biochemical characteristics of the individual photosensitizers and the variation in their interactions with the delivery/distribution environment.

Allantois↗
PubMed1993

Experimental study on the formation of the epicardium in chick embryos.

In chick embryos, the formation of the epicardium proceeds from the attachment of a secondary sinuventricular mesocardium. This mesocardium is formed by the adhesion of pericardial villi with the dorsal surface of the heart. It was the aim of this study to clarify the role of the pericardial villi in the formation of the epicardium. For this purpose, the contact between the pericardial villi and the heart was prevented by placement of a piece of the shell membrane between them. After re-incubation, the hearts of the experimental embryos could be assigned to one of two different groups: hearts completely lacking a secondary mesocardium (Group A), and hearts without the sinu-ventricular but with a dystopic secondary mesocardium (Group B). In Group A, the formation of the epicardium and subepicardial mesenchyme was found to be severely disturbed. In Group B, the formation of the epicardium proceeded from the point of attachment of a dystopic secondary mesocardium; defective development of the subepicardial mesenchyme was not encountered. These results support the view that the epicardium is derived from the pericardial epithelium.

Animals↗
PubMed1975

Cellular RNA and influenza-virion RNA are synthesized from different pyrimidine-nucleoside-triphosphate pools in chick-embryo cells.

Chick embryo cells infected with an influenza A (fowl plague) virus have been labelled with (3H)-uridine for different lengths of time. Virion RNA and cellular RNA have been separated by specific hybridization with a surplus of unlabelled viral complementary RNA and RNase digestion. The ratio of the specific radioacticity in the UMP and CMP moieties of both types of RNA has been determined. Since the rate of approach to equilibrium of CMP to UMP labelling of both types of RNA is completely different it is concluded that cellular and virion RNA are synthesized using different pyrimidine nucleoside triphosphate pools.

Animals↗
PubMed1991

Isonicotinic acid hydrazide inhibits cell population growth during teratogenesis of chick embryo.

In chick embryos treated with a 4 hr pulse of 7.2 X 10(-5) M isonicotinic acid hydrazide (INH) the cell population growth is inhibited with an increased population doubling time. Teratogenised blastoderm cells complete their ongoing cell cycle and arrest in G1 phase. A chase with an equimolar concentration of pyridoxal-5-phosphate restores the growth rate after a lag of 4 hr equivalent to the duration of treatment with INH. Presumptive mesoblast cells invaginated through the primitive streak and neuroectoblast cells induced prior to the application of INH differentiate, while the teratogen inhibits morphogenesis and organization of organ primordia.

Animals↗
PubMed1969

Influence of the rate of cell growth and cell density on interferon action in chick embryo cells.

Chick embryo cells became more sensitive to the action of interferon the longer they remained in culture. This phenomenon was found even before confluency had been reached. The relative insensitivity of newly seeded cells was not due to a loss of receptors. Cells synthesizing deoxyribonucleic acid (DNA) at a high rate were less sensitive to interferon action than cells synthesizing DNA at a low rate, but the inhibition of DNA synthesis had no effect on interferon action. An increase in the number of cells used for seeding resulted in an earlier appearance of increased sensitivity to interferon action. These results are discussed in relation to the induction process in animal cells.

Animals↗
PubMed1986

Glycosphingolipid biosynthesis in early chick embryos.

Early chick embryos at the age of 22 h (neurula stage) and 48 h (20-25 somite stage) were explanted from eggs and cultured in vitro in the presence of radioactive sugar precursors. Metabolically labelled glycosphingolipids were isolated. Amongst these, neutral and acidic components, the latter including sulfatide and gangliosides, were identified. Cleavage by exoglycosidases, as well as immunostaining with antibodies on thin-layer plates, showed that at both embryonic stages glycosphingolipids were synthesized that belong to the globo series (globoside, Forssman glycolipid), the lacto series (lactoneotetraosylceramide, nLc4Cer, and two nLc4Cer-based gangliosides, a monosialo and a disialo species), and the ganglio series (ganglioside Gtet1a and higher sialylated derivatives).

Animals↗
PubMed1990

Early aspects of sex differentiation in the gonads of chick embryos.

In chick embryos whose sex had been previously identified by cytokaryologic methods, a light-microscope study of the number and dimensions of the germ cells (GCs) has been made from 2 to 7 days of incubation. Early differences between the sexes have been found. In females the GCs were larger and increased in number earlier than in males. This suggests an earlier differentiation of GCs in females. On the other hand, ultrastructural observations on GCs at 70 h incubation (colonization stage of the genital ridges) have revealed that male and female GCs differ from each other mainly in the amount of rough and smooth endoplasmic reticulum, mitochondria, glycogen particles and lipid droplets. This suggests early morpho-functional differences between male and female GCs.

Animals↗