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PubMed1969

Plaquing of Toxoplasma gondii in secondary cultures of chick embryo fibroblasts.

A tissue culture system that employed chick embryo fibroblasts was described for plaquing of the obligate intracellular parasite Toxoplasma gondii. High plaquing efficiency and reproducibility were accomplished by the use of secondary rather than primary cultures and the use of toxoplasma obtained from disrupted peritoneal cells of mice infected 48 hr earlier. The monolayers were cultured in a special medium which maintained the fibroblasts until the maximal number of plaques was produced. Optimal plaque formation was obtained in 5 days, and the plaques were easily counted macroscopically.

Animals↗

PubMed2001

Extrapituitary beta TSH and GH in early chick embryos.

Somatotropes and thyrotropes are thought to be derived from the same cellular lineage and the expression of both growth hormone (GH) and thyrotropin (beta TSH) is thought to be dependent upon the same (Pit-1) transcription factor. The presence and comparative distribution of GH- and beta TSH-immunoreactivity in early chick embryos, was therefore investigated, especially as extrapituitary GH-immunoreactive cells are present in some peripheral tissues of early chick embryos prior to the ontogenic differentiation of the pituitary gland. At the end of the first trimester of incubation (embryonic day (ED) 7), GH-immunoreactivity was widespread in the head, particularly in neural tissue. Strong labeling was found in the diencephalon and mesencephalon and in neural ganglia and the trigeminal nerve. beta TSH-immunoreactivity was also present in these tissues, although restricted to the ependymal cells lining the diocoele and mesocoele and absent from mantle layers. It was also present in the cellular layer lining the otic vesicle, which was devoid of GH staining. In contrast, Rathke's pouch, the primordial pituitary gland was without GH- or beta TSH-staining. Control sections incubated with preabsorbed antisera or with pre-immune serum were completely devoid of staining. In the trunk, the epidermal cells were stained for beta TSH, but not for GH. Intense GH-immunoreactivity was present in the ventral and dorsal horns of the spinal cord and was particularly strong in the outer marginal layer. In contrast, beta TSH-immunoreactivity was again restricted to ependymal cells lining the spinal canal, which were devoid of GH-immunoreactivity. Strong GH staining was also present in the dorsal and ventral root ganglia, both of which lacked significant beta TSH staining. In non-neural tissues, both GH and beta TSH staining was present in the crop, although in topographically different cells. beta TSH-immunoreactivity was also present in the cells lining the bronchial ducts and the adluminal linings of the pleural and pericardial cavities. GH-immunoreactivity, in contrast, was absent from the lung but present in the surrounding intracostal muscles and in the Müllerian duct. Both GH- and beta TSH-immunoreactivity was present in liver hepatocytes. These results clearly show, for the first time, the presence of TSH-immunoreactivity in central and peripheral tissues of the ED7 chick embryo, prior to the differentiation of pituitary thyrotropes. They also show that beta TSH- and GH-immunoreactive cells are differentially located within embryonic tissues.

Animals↗

PubMedDate not supplied

[The characteristics of the stimulation of the proliferation of cultured chick embryo cells during reseeding].

The growth rate of chick embryo cells in slowly proliferating cultures is activated after substitution of conditioned medium by fresh one with serum. After cell replanting, the stimulation of cell proliferation takes place in both media with the same effectiveness. In serum-less medium replanted cells do not adhere to glass and die. The results suggest that cells reversibly lose their dependence upon serum growth factors and population density, as a result of replanting, but retain anchorage-dependence for growth.

Animals↗

PubMed1980

[Electrophoretic characterization of glycosaminoglycans during development of the chick embryo skin].

Glycosaminoglycans extracted by CPC precipitation from chick embryo skin at 9, 12, 15, 18, 21 days of incubation were separated by three different electrophoretic methods on acetate cellulose strips. We observed the presence of Hyaluronic acid, Dermatan Sulfate and Chondroitin-4-Sulfate during the whole period considered and of Heparan Sulfate only after the 9th day. Dermatan Sulfate increases until the 15th day then decreases progressively; on the contrary Hyaluronic acid and Chondroitin-4-Sulfate decrease during days 9 to 15 then increase until hatching. Heparan Sulfate appear the 9th day then increases progressively until hatching.

Animals↗

PubMed1975

Morphology of A/WSN influenza virus-infected chick embryo cells.

A/WSN (H0N1) influenza virus-infected chick embryo cells (CEC) attained a swollen central region 4 hours post infection (p.i.), different from the elongated uninfected cell. From 6 hours p.i. of CEC an increasing number of approximately 100-120 nm, round protrusions were observed by scanning and transmission electron microscopy on the cell membrane, which was smooth on the uninfected cell. At 48 hours p.i. a great number of protrusions were observed on the cell; in addition, there were a number of holes or invaginations in the membranes of the infected cells indicating cell destruction.

Animals↗

PubMed1998

Regulation of rhythmic melatonin production in pineal cells of chick embryo by cyclic AMP.

The pineal cells of chick embryos incubated in vitro exhibited a daily rhythm of melatonin synthesis under a 12:12 light:dark (LD) cycle at the embryonic days 16 and 19. In order to elucidate whether cyclic adenosine monophosphate (cAMP)--a component of the melatonin generating system--is already at work in the embryonic period, we measured the effects of forskolin and isobuthylmethylxantine (IBMX) on melatonin production, cAMP efflux and accumulation. Forskolin (after 10, 20, 30, 45, 60 and 90 min of administration) and IBMX (6 h), when applied during the light phase of LD cycle, stimulated melatonin production and cAMP efflux and accumulation during the embryonic period (at days 16 and 19 fo development). Our results suggest that the biochemical pathway involving cAMP, which controls melatonin production in the postnatal period, is developed before hatching and already on embryonic day 19 works in a way similar to that in post-hatched chicks. Differences in response to cAMP stimulation between 16- and 19-day-old pinealocytes seem to be mostly quantitative.

1-Methyl-3-isobutylxanthine↗

PubMed1984

Ketogenesis in chick embryo isolated hepatocytes.

Isolated hepatocytes from 17-day chick embryos exhibit high endogenous rates of ketogenesis. The addition of long-chain fatty acids stimulated ketogenesis with potency ordered as follows: palmitate greater than oleate greater than stearate. Octanoate produced a slight stimulation of ketogenesis when added at low concentrations (less than 0.25 mM). At higher concentrations the effect of octanoate was inhibitory. The addition of glucose to incubations failed to lessen endogenous ketogenesis whereas propionate, pyruvate and lactate produced inhibition. Ketogenesis from both endogenous sources and added fatty acids was not altered by the addition of glucagon, insulin, adrenalin or vasopresin.

Animals↗

PubMed1990

Hyaluronic acid promotes chick embryo fibroblast and chondroblast expression.

15-day-chick-embryo fibroblasts and chondroblasts were cultured in the presence of high and low molecular weight exogenous hyaluronic acid (HA). Growth range and incorporation of radiolabelled sulphate and proline were determined. HA reduced cell proliferation to about 75% of controls, while incorporation of radiolabelled sulphate and proline was higher in HA-treated cultures of both chondroblasts and fibroblasts. The effect was not due to the polyanionic or polymeric nature of the molecule and appeared to be highly specific for HA.

Animals↗

PubMed1990

Effects of lectins on cytoskeleton and morphology or cultured chick embryo fibroblasts.

The microfilaments and microtubules of cultured chick embryo skin fibroblasts were studied in the presence of exogenous lectins by an indirect immunofluorescence technique. Lectin treatment induced modifications in the arrangement of myosin, actin and tubulin, determined depolymerization of the proteins and caused changes in cell shape and size. The results suggest that the interaction between lectins and their specific membrane receptors triggers a series of changes in the cytoskeletal pattern via transmembrana as yet unknown mechanisms and that these are responsible for the alterations in cell shape and size.

Actin Cytoskeleton↗

PubMed1993

Strain-dependent effect of ethanol on ventricular septal defect frequency in White Leghorn chick embryos.

We have tested the potential of a single dose of ethanol (0.20 ml 50% ethanol in chick Ringer's saline (CRS) administered into the air sac) to produce ventricular septal defect (VSD) in three distinct commercially available strains of White Leghorn chick embryo: stress-resistant Dekalb Delta strain, Hy-Vac SPF type V, and Hy-Vac SPF type L. Eggs were controlled for both size and developmental stage (Hamburger-Hamilton stage 18-19) at time of injection. The frequency of VSD in Dekalb Delta embryos was 4.0% (1/25), in Hy-Vac SPF type L embryos 9.1% (3/33), and in Hy-Vac SPF type V embryos 38.9% (14/36). Statistical analysis with the two-tailed Fisher Exact Test indicated that frequencies were not significantly different (P = 0.3215) when Dekalb Delta and Hy-Vac type L embryos were compared. However, the frequency of VSD for Hy-Vac type V embryos was significantly greater than that for either the Dekalb Delta or the Hy-Vac type L embryos (P < 0.005). All VSDs observed were located within the crista supraventricularis. When Hy-Vac SPF type V embryos were exposed to either 0.20 ml 50% ethanol in CRS or to 0.20 ml CRS (controls), ethanol-treated embryos showed a VSD incidence of 34.1% compared with a 3.6% incidence in the controls (P = 0.0017). These data suggest that ethanol is the cause of VSD in this strain. From the results of this study, we are led to conclude that different commercial strains of White Leghorn chick embryo show different susceptibilities to the induction of VSD by ethanol.

Animals↗

PubMed1981

Replication of poxvirus DNA in chick embryo fibroblasts.

Replication of vaccinia virus DNA in chick embryo fibroblasts at a high multiplicity of infection started after 4-6 hr, reached a maximum at the 12th hr and was completed 18 hr after inoculation (p.i.). An analysis of newly synthesised DNAs in the period of the highest rate of synthesis revealed the formation of short (10-30S) fragments which within 30 min were transformed into single-stranded molecules with a sedimentation coefficient of 62S. The final stage of closing of the ends of single-stranded molecules needed much more time and the bulk of "mature" single-stranded 90 S DNA molecules was observed 17 hr p.i.

Animals↗

PubMed1993

Origin of the avian glycogen body. II. Observations in support of a glial nature in the chick embryo.

Stem cells of the glycogen body in chick embryos at 7-8 days of incubation (stages 31-34) were studied by light microscopy autoradiography, immunocytochemistry, and following induced spina bifida to discern their nature and origin. Glycogen cells displayed the presence of glial fibrillar acid protein and vimentin at the time of their appearance at 7-8 days of incubation (stages 31-34). Displayed also were indications of DNA synthesis by thymidine incorporation during that period of development. Observations suggest that glycogen body cells are glial in nature, possibly radial glia which arise from neuroepithelium that comprises the ependyma and roof plate of the avian lumbosacral spinal cord.

Animals↗

PubMed1981

Cell junctions in explanted tissues from early chick embryos.

Hypoblast and definitive endoblast derived from young chick embryos were explanted and grown for 24 h in culture. The junctional complexes which characterise these tissues were studied on freeze-fracture replicas and thin sections. Cell membranes of the hypoblast displayed tight junctions only, disposed in randomly arranged strands or narrow belts which included many discontinuous strands. The definitive endoblast showed tight and gap junctions as well as desmosomes in close association with the tight junctions. It is suggested that the differences between the two types of tissue may be related to cell cohesiveness, which appears to be relatively low in the hypoblast and high in the definitive endoblast.

Animals↗

PubMed2000

Teratogenic effects of sinusoidal extremely low frequency electromagnetic fields on morphology of 24 hr chick embryos.

To examine the potential teratogenicity of electromagnetic fields (EMF; sinusoidal and rectangular) on development of chick embryos (white leghorn), 221 freshly fertilized chicken eggs (55-65 g) were exposed during first 24 hr of postlaying incubation (38 degrees +/- 0.5 degree C) to 24 different EMFs, with 50Hz repetition rate and 8.007-10.143 mT flux density. Following exposure, the exposed fertilized chicken eggs (n = 8-10) and sham-exposed fertilized chicken eggs (n = 15) were incubated simultaneously for 8 more days and unexposed control fertilized chicken eggs (n = 20) for 9 days in absence of EMFs. The embryos were removed from egg shells and studied blind. All 24 EMF exposed-groups (inside the coil with exposure) showed an increase in the percentage of developmental anomalies compared to sham-exposed (inside the coil with no exposure) and control groups (outside the coil). Further, egg's weight was evaluated on day 9. This variable did not show significant difference between control and exposed-groups. The investigation also covered the measurement of body weight, length of crown to rump, length of tip of the beak to occipital bone, heart and liver weight. Statistical comparison between sham-exposed and control values did not show significant differences, but comparison between 8.007, 8.453 and 8.713 mT exposed-groups and control groups showed significant differences; in other exposed-groups, the changes were not significant. These results revealed that 50 Hz electromagnetic fields can induce irreversible developmental alterations in 24 hr chick embryos and confirm that its strength could be a determinant factor for the embryonic response to extremely low frequency electromagnetic fields (window effects).

Animals↗

PubMed1981

A golgi study on the early sequence of differentiation of ganglion cells in the chick embryo retina.

An examination of retinal structure in chick embryos, impregnated with the Golgi-Stensaas method between 2 and 6 days of incubation, discloses, on the one hand, a uniform typology of the proliferating ventricular cells, the pre- and postmitotic forms of which were tentatively identified; on the other hand, postmitotic neuroblasts are evidenced in the stages of differentiation previous to the growth of their neurites. In the earliest embryos (up to 5 1/2 days of incubation), all cells that detach from the ventricular lining to differentiate as neurons do so while the ventricular cell precursor has an interphasic configuration. This means that, although they free themselves from the scleral attachment site, they keep for a while a vitreal attachment. The vitreally-attached endfeet subsequently transform into axonal growth cones, sprouting filopodia and lamellipodia. While the axons grow towards the optic nerve head, cell bodies and remaining scleral processes are progressively retracted inwards, leading to the appearance of typical ganglion cells. After 5 1/2 days of incubation, a great number of postmitotic neuroblasts detach while still in the G1 phase of the ventricular cell cycle. Those of them that show the longest leading processes become also ganglion cells, after their leading tip has acquired a growth cone configuration and has bent into the optic fiber layer. These results on early mechanisms of ganglion cell genesis are discussed in relation to data in the literature, and a simple hypothesis is offered which explains the biphasic pattern in which presumptive ganglion cells detach from the ventricular lining of the chick retina.

Animals↗

PubMed1977

Developmental decline in DNA repair in neural retina cells of chick embryos. Persistent deficiency of repair competence in a cell line derived from late embryos.

Neural retinas of 6-day-old chick embryos synthesize DNA and are able to carry out DNA excision repair. However, in contrast to the situation in human cells, the maximum rate of repair induced by N-acetoxy acetylaminofluorene (AAAF) is no greater than that induced by methyl methanesulfonate (MMS). With advancing differentiation of the retina in the embryo, cell multiplication and DNA synthesis decline and cease, and concurrently the cells lose the ability to carry out DNA excision repair. Thus, in 15-16-day embryos, in which the level of DNA synthesis is very low, DNA repair is barely detectable. If retinas from 14-day embryos are dissociated with trypsin and the cell suspension is plated in growth- promoting medium, DNA synthesis is reinitiated; however, in these cultures there is no detectable repair of MMS-induced damage, and only low levels of repair are observed after treatment with AAAF. A cell line was produced, by repeated passaging of these cultures, in which the cell population reached a steady state of DNA replication. However, the cell population remained deficient in the ability to repair MMS-induced damage. This cell line most likely predominantly comprises cells of retino-glial origin. Possible correlations between deficiency in DNA repair mechanisms in replicating cells and carcinogenesis in neural tissues are discussed.

Acetoxyacetylaminofluorene↗

PubMed1982

Insulin is present in chicken eggs and early chick embryos.

We showed that insulin appears in the chick embryo before beta-cells are recognizable, as well as in the egg constituents even before fertilization. Acid-ethanol extracts of 2- to 8-day-old embryos were gel-filtered on Sephadex G-50. The peak of immunoreactive insulin chromatographed in a position corresponding to that of authentic insulin. The immunoreactive insulin extracted from embryos was approximately 2 ng/g wet wt during early embryogenesis (days 2, 3, and 4), with a 2- to 3- fold increase by days 5 and 6, in conjunction with pancreatic development. The heads of the embryos contributed 22-23% of the total insulin on days 3 and 4, but only 5% by day 5. Based on its reactivity in a pork insulin RIA, chicken insulin RIA, and rat adipocyte bioassay, we concluded that the material is very similar to avian (chicken or turkey) rather than mammalian type insulin. Similar immunological and biological insulin-like activity [but at much lower concentrations (0.2-0.8 ng/ml)] were recovered from the gel-filtered acid-ethanol extracts of yolk and white of unfertilized and fertilized eggs. This study, which shows that insulin is present at a very early stage in ontogeny, extends observations that insulin is native to organisms that lack pancreatic islets, including flies, worms, and microbes.

Adipose Tissue↗

PubMed1991

Histological examination of chick embryos with bilateral microphthalmus with reference to laterality in the visual apparatuses.

The histological abnormalities of chick embryos with bilateral microphthalmus were examined in serial paraffin sections with special reference to laterality in the visual apparatuses, including the cornea, lens, neural retina and pigment epithelium. There was marked laterality in the above structures; some eyeballs had individual, if incomplete, sublayers of the cornea and the neural retina, and others not. The sublayers of the neural retina were occasionally observed even in eyeballs at the stage of optic vesicle formation, in contrast to the previous notion that the pigment epithelium induces the maturation of the primordial neural retina after optic vesicle differentiation into the optic cup. There was also a case where developmental differences between the right and left eyeballs were absent except in the lens. These findings suggest that chick embryos with bilateral microphthalmus exhibit a more complex histological profile or diversity than previously considered, possibly as a result of the differential actions of various mutagens and endogenous trophic factors on the developing visual system.

Animals↗