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PubMed1991

[Crossed graft of embryonic testis between quail and chick embryos: contribution to the study of the mechanism of female bird embryo masculinization].

Quail, or chick embryonic testes grafted respectively in the extraembryonic coelom of chick or quail embryos induce both a Mullerian duct regression and a masculinization of the female host gonads up to the differentiation of two testes, in some cases. Such a result confirms the fact evidenced previously in other bird species (chick and duck) that the testis-inducer is interspecific. Quail cells are not observed in histological sections of embryonic gonads of testis-grafted chicks. This allows to discard a possible influence of cells migrating from the graft to the host. The grafted testes act then through substance/s secreted in the blood stream. Present and previous experimental data strongly suggest that the same substance, i.e. the so-called anti-Mullerian hormone, is responsible for both MD regression and gonadal sex reversal.

Animals↗
PubMed1977

Growth and mineral content of cultured chick embryos.

In order to assess mineral uptake by chick embryos cultured outside of the shell, growth and mineral (Ca, Mg, K, Na) composition of control and cultured embryos and total egg contents (embryo plus residual egg contents) were measured from 8 through 21 days of incubation. At day nine and thereafter, cultured embryos contained significantly less Ca and Mg than did control embryos. At day 11 and thereafter, ash weight of cultured embryos was significantly less than that of controls. At 13 days and thereafter, wet weight, dry weight, toe length, K and Na content of cultured embryos were significantly less than in controls. To assess relative mineral uptake of cultured embryos, mineral (Ca, Mg, K, Na) content per gram embryo dry weight was plotted against incubation age. Values for the ratio of Mg, K and Na per gram dry weight were similar for control and cultured embryos. Control values for Ca per dry weight were consistently higher than those for cultured embryos during the period from 9 to 21 days. The data suggest that Ca may not be present in sufficient quantity, even on a relative growth basis, to perform its normal physiological functions in cultured embryos.

Animals↗
PubMed1992

Effects of surgical decapitation and chicken growth hormone (cGH) replacement therapy on chick embryo growth.

The effects of decapitation and chicken growth hormone (cGH) replacement therapy on chick embryo growth has been investigated. Removal of the prosencephalon at 33-38 hrs (1.38 to 1.58 Days) of incubation decreased body (torso) and liver weights as well as skeletal growth as indicated by tibial length. A single pituitary gland transplanted onto the chorioallantoic membrane (CAM) partially restored torso growth and completely reversed the increase in body water content which characterizes decapitated embryos. Replacement therapy with cGH did not influence body weight but did, on Day 16.5 of incubation, increase tibial length and liver DNA content and concentration. These latter findings suggest that there may be limited hypothalamoadenohypophyseal (GH) axis function in the chick embryo. The effects of decapitation on torso growth are also discussed in conjunction with decapitation effects on albumen swallowing (absorption) and yolk absorption.

Albumins↗
PubMed1990

Origin of the proximal coronary artery stems and a review of ventricular vascularization in the chick embryo.

The objective of this study was to determine how the coronary artery stems develop in the chick embryo. The hearts of 51 ink-injected and cleared chick embryos, aged embryonic days 6, 6.5, 7, 7.5, 9, and 10, were dissected, examined, and selectively photographed. Two representative hearts from each group were paraffin embedded, serially sectioned at 10 microns, and examined for aortic endothelial budding. We found that the proximal coronary artery did not appear to grow outward from the aorta as commonly described in the literature. It appeared to originate from a capillary ring which encircled the aortic and pulmonary outflow tracts. On embryonic day 7.5, one to three channels arising from this ring penetrated each aortic sinus, in an area of darker textured endothelium. Histologically and grossly, multiple channels were still apparent on day 9, particularly in the left coronary artery. One of these channels always became dominant to form the stem. Each stem, which varied in length from embryo to embryo, always ended in a plexus of sinusoidal endothelial tubes. By day 10, the coronary artery stems were longer, with many major branches. Histologically, evidence of multiple channels still was visible. It is significant that channels from the bulbar vascular ring penetrated the aorta at very specific points in the aortic sinuses and did not penetrate the pulmonary trunk or other aortic sites. We believe this fact indicates that the penetration of the aortic sinuses by channels from the bulbar vascular ring represents a controlled invasion of the aorta.

Animals↗
PubMed1993

Chick embryo, a model to study the lethal activity of pertussis toxin, infectivity of Bordetella pertussis, and their neutralization by immune sera.

The toxin activity of Bordetella strains and acellular pertussis components was evaluated in chick embryos. Eleven-day-old embryos were found to be most suitable for determination of LD50 values. Eight of eight Bordetella pertussis strains possessed LD50 values of 10(4) to 10(6) colony-forming units per dose of 100 microL. Embryos were resistant to Bordetella parapertussis and Bordetella bronchiseptica at doses of 10(10) colony-forming units. Bacterial growth did not occur in the bloodstream or tissues of the heart, kidney, brain, liver, or lungs. Pertussis toxin activity, determined by clustering of Chinese hamster ovary cells, was found in the allantoic fluid following inoculation of virulent bacteria. Purified pertussis toxin had an LD50 of 1-2 micrograms protein/dose. Striking pathological effects of liver necrosis and oedema of the head and neck were similar following bacterial or toxin inoculation. Widespread changes occurred in the liver at the perivascular level, suggesting that after allantoic inoculation of virulent Bordetella strains, toxin is secreted, carried in the bloodstream, and causes the resultant pathology. Purified B. pertussis lipopolysaccharide was nontoxic for embryos at doses containing 30 micrograms; filamentous haemagglutinin was nontoxic at doses up to 10 micrograms. A correlation exists between the ability of serum to neutralize killing of chick embryos by toxin and to neutralize clustering of Chinese hamster ovary cells by toxin. Although the chick embryo serum neutralization studies confirm observations of mouse intracerebral infection studies that antibody to pertussis toxin is not an absolute requirement for prevention of infection with B. pertussis, evidence is provided that anti-toxin will eliminate toxic effects owing to secretion of pertussis toxin.

Allantois↗
PubMed1978

Contribution of human somatomedin activity to the serum growth requirement of human skin fibroblasts and chick embryo fibroblasts in culture.

Although purified human somatomedins and related peptides have been shown to stimulate growth-related processes in cultured human skin fibroblasts, it is unknown whether the serum macromolecules required for the routine growth of human fibroblasts in culture include the somatomedins. To evaluate this question we have obtained sera from five GH-deficient patients before and after GH treatment and have compared these pre- and post-GH sera for their ability to stimulate [3H]thymidine incorporation into DNA and cell multiplication in the patients' own fibroblasts in culture. Subconfluent human fibroblasts demonstrated a dose-dependent increase in thymidine incorporation and cell number when exposed to human sera. Pre- and post-GH sera were equipotent. Partial purification of somatomedin activity by boiling sera at pH 5.5 diminished the level of thymidine incorporation to 10-20% of the level achieved with unboiled sera but did not unmask a difference between pre- and post-GH sera. In contrast to the results in human fibroblasts, boiled post-GH sera were 2- to 5-fold more potent than pre-GH sera in stimulating thymidine incorporation in chick embryo fibroblasts. Mixing experiments failed to demonstrate inhibition of thymidine incorporation by boiled pre-GH sera. Boiled post-GH sera also were twice as active as boiled pre-GH sera in stimulating multiplication of chick embryo fibroblasts and confirmed that thymidine incorporation reflected DNA synthesis. GH added directly to chick embryo fibroblasts did not stimulate thymidine incorporation. We conclude that despite the presence of specific receptors for somatomedin-like peptides on human skin fibroblasts, somatomedins are not a major component of the serum macromolecules required for the routine growth of human fibroblasts in culture. In contrast, in chick embryo fibroblasts, somatomedins do appear to constitute an important part of the serum macromolecules supporting cell growth.

Animals↗
PubMed1996

The changes of spontaneous motility in chick embryos after blockade of NO-synthase.

The consequences of the blockade of NO-synthase (NOS) for the development, frequency and reactivity of spontaneous motility were investigated in chick embryos aged 4-19 day of incubation. 1. Acute NOS blockade evoked by N-nitro-L-arginine- methylester (L-NAME) (20 mg/kg egg weight-e.w.) caused on day 17 of incubation the short-lasting depression of spontaneous motility to 50% of resting motor activity. L-NAME was in spinal embryos without any effect. Chronic application of L-NAME (1.70 mg/kg e.w./24 h) from day 4 of incubation led after the first 4 days of continual supply to the development of reduced spontaneous motility on one hand, on the other hand it changed the efficacy of central activatory (NMDA, pentylenetetrazole) and inhibitory drugs (ketamine, glycine). L-NAME and L-arginine in different mutual combinations manifested in 17-day-old embryos their typical effect, though the depressory effect of L-NAME took a swifter course than the activatory effect of L-arginine. 2. Aminoguanidine (AmG) (9.8 and 20 mg/kg e.w.) evoked from day 17 of incubation the significant biphasic change of spontaneous motility only: initial depression was replaced by later activation. AmG was in spinal embryos without effect again. Chronic application of AmG (5.29 +/- 0.51 mg/kg e.w./24 h) showed in 17-day-old embryos a reduction of resting motility dependent on the duration of AmG influence during incubation. Another expression was the changed reactivity of spontaneous motility to some centrally effective drugs (ketamine, NMDA, D-cycloserine, glycine, pentylenetetrazole). 3. 7-nitroindazole (7-NIZ) (15 and 30 mg/kg e.w.) caused the significant decrease of spontaneous motility in chick embryos already from day 15 of incubation; the depression after the lower dosis had an interrupted course, whereas after the higher dosis it was a continuous one. 7-NIZ blocked in 17-day-old embryos the activatory effect of L-arginine, reduced the paroxysmal activation of motility evoked by NMDA and blocked the activatory effect of both drugs at simultaneous application. 4. The results support the idea that in the CNS of chick embryos NO-ergic mechanism connected with spontaneous motility and cooperating with NMDA-ergic neuronal activation develops within the last quarter of 21-day incubation.

Animals↗
PubMed1996

A novel radiological approach for the experimental study of angiogenesis: angiography of the chick embryo and its chorioallantoic membrane.

We use a modification of the digital substraction angiography (DSA) technique to visualize the vascular system of the chorioallantoic membrane (CAM) of the developing chick embryo. After catheterization of the central vein of the CAM with a metallic needle and injection of contrast medium, angiography was performed at specified follow-up intervals (1-2.5 images per second) using the Philips DVI-S Angiography Unit. By applying the vascular casting technique we were able to visualize the vessels of the CAM and to study the existing complex vascular-anatomical relationships. Our results show that DSA demonstrates the development of the circulatory system of the chick embryo (heart and vessels) and the vessels of its CAM effectively. By applying for the first time interventional radiology techniques on the chick embryo system, it has been possible to study morphological changes of the vessels during angiogenesis in vivo. These results suggest that this technique can be a proven and valuable tool in the quantitative assessment of angiogenesis.

Allantois↗
PubMed1976

[Pathogenicity of K. ozaenae for mice and chick embryos].

The authors tested the virulence of K. ozaenae--its old museum strains, the freshly isolated ones and those passaged on meat-peptone agar; experiments were carried out on mice and chick embryos. To mice the culture was administered intraperitoneally, subcutaneously, intranasally, and to embryos--into the allantoic cavity and on the chorioallantoic membrane. Irrespective of the method of administration, the freshly isolated strains were highly virulent both for mice and for chick embryos. The virulence of such strains decreased in the process of passaging on the nutrient medium. Old museum strains were of low virulence for albino mice and avirulent for chick embryos. In comparing the virulent and avirulent strains there were found no differences in the antigenic structure and toxicity of the Boiven complex, cytoplasm, membrane, capsular polysaccharide or whole virulent and avirulent bacteria killed by heating.

Animals↗
PubMed1993

Second messenger regulation of occlusion of the spinal neurocoel in the chick embryo.

We know that, once rostral neurulation is completed in the neuroaxis of the chick embryo, the caudal neurocoel becomes occluded and the brain rapidly expands. However, very little is known about the mechanisms maintaining occlusion. Studies had shown that occluded neurocoels reopened in embryos treated with chelators of cations, but the reasons remained unclear and the cations unidentified. To begin defining the role of cations, this study explored the effect of Ca2+, calmodulin, and cAMP on maintaining the occluded neurocoel. Chick embryos during the natural phase of neurocoel occlusion (stage 12) were cultured in vitro with drugs known to modulate Ca2+ transport, to inhibit calmodulin activity, or to elevate cAMP levels. To test if occlusion is a Ca(2+)-dependent process, embryos were treated with verapamil and ionophore A23187. To test if occlusion requires calmodulin, embryos were treated with antipsychotic agents. To test if occlusion is cAMP dependent, embryos were treated with methylisobutylxanthine (MIX), forskolin (FOR), or dibutyl cyclic adenosine (DbC). Following each treatment, occlusion of the neurocoel was tested by injecting dye into the midbrain. All treatments resulted in a predominant number of precocious reopenings of the occluded neurocoels. MIX-treated, naked neural tubes had a four-fold increase in cAMP, whereas FOR- and DbC-treated neural tubes showed ten- and 14-fold increases, respectively. The presence of calmodulin in the cells of the neural tube was confirmed by fluorescent tagging and 3H-chlorpromazine labelling. The combined results of this study show that occlusion of the spinal neurocoel depends on exogenous Ca2+, requires calmodulin, and is cAMP sensitive.

Animals↗
PubMed1999

FGF7 and FGF10 directly induce the apical ectodermal ridge in chick embryos.

During vertebrate limb development, the apical ectodermal ridge (AER) plays a vital role in both limb initiation and distal outgrowth of the limb bud. In the early chick embryo the prelimb bud mesoderm induces the AER in the overlying ectoderm. However, the direct inducer of the AER remains unknown. Here we report that FGF7 and FGF10, members of the fibroblast growth factor family, are the best candidates for the direct inducer of the AER. FGF7 induces an ectopic AER in the flank ectoderm of the chick embryo in a different manner from FGF1, -2, and -4 and activates the expression of Fgf8, an AER marker gene, in a cultured flank ectoderm without the mesoderm. Remarkably, FGF7 and FGF10 applied in the back induced an ectopic AER in the dorsal median ectoderm. Our results suggest that FGF7 and FGF10 directly induce the AER in the ectoderm both of the flank and of the dorsal midline and that these two regions have the competence for AER induction. Formation of the AER of the dorsal median ectoderm in the chick embryo is likely to appear as a vestige of the dorsal fin of the ancestors.

Animals↗
PubMed1983

Hypothalamo-adenohypophyseal-thyroid and gonadal interrelationship in the chick embryo. I. Differential effect of ectopic pituitary grafts on plasma total T4 and testosterone levels.

Plasma total thyroxine (T4) and testosterone concentrations of Day 15.5 intact, surgically partially decapitated (hypothalamo-hypophyseoprivic) and partially decapitated chick embryos with adenohypophyseal transplants were determined by radioimmunoassay of the same plasma sample. Decapitation in both male and female chick embryos at 33-38 h of incubation results in plasma thyroxine and testosterone levels which are statistically significantly lower than those of intact embryos. The addition of a single adenohypophyseal transplant to the chorioallantoic membrane (CAM) of male and female decapitated embryos only partially restores plasma thyroxine levels to intact levels. However, the same procedure results in plasma testosterone levels which are higher than those of both decapitated and intact individuals. The data suggest that in the developing chick embryo there are differences in dependence of the thyroid and the gonads upon a functional hypothalamo-adenohypophyseal unit. The possible differential regulatory effects of the hypothalamus on the adenohypophyseal-thyroid and adenohypophyseal-gonadal components of the hypothalamic-adenohypophyseal-thyroid and hypothalamic-adenohypophyseal-gonadal axes are discussed.

Animals↗
PubMed1983

Toxicity and distribution in chick embryos of 3,3',4,4'-tetrachlorobiphenyl injected into the eggs.

3,3',4,4'-Tetrachlorobiphenyl (3TCB) was injected into the yolk of embryonated hens' eggs in doses of 4, 20 or 100 micrograms/kg egg. Twenty and 100 micrograms/kg resulted in the death of all the embryos. The hatching rate of the eggs treated with 4 micrograms/kg was 60% while that of the control eggs was 88%. This means that 3TCB is at least 10 000 times more toxic in chick embryos than a previously studied isomer, 2,2',4,5'-tetrachlorobiphenyl (2TCB). 3,3',4,4'-Tetrachlorobiphenyl might be teratogenic in chick embryos since eye and beak deformities were seen in 3 unhatched tetrachlorobiphenyl-treated embryos. In addition rump edema and excess fluid in the body cavity was observed in some embryos. The distribution of the 2 tetrachlorobiphenyls in chick embryos was studied by means of whole-body autoradiography. No differences in distribution, which could explain the extreme difference in toxicity, were detected. High amounts of radioactivity were found in the bile of the embryos, indicating a capacity of the embryos to metabolize and excrete the tetrachlorobiphenyls.

Abnormalities, Drug-Induced↗
PubMed1992

Development of melatonin rhythm in the pineal gland and eyes of chick embryo.

A melatonin rhythm was observed in the pineals of 18-day-old chick embryos incubated under a light-dark regime of 18: 6 h. A low pineal melatonin content was found during the light phase of the day. Concentrations started to increase 2 h after dark onset and reached maximum levels after 4 h of darkness. The amplitude of the pineal melatonin rhythm increased considerably after 2 days and night-time concentrations in 20-day-old embryos were more than 5 times higher than in 18-day-old ones. Significant day/night differences in melatonin production were found both in pineals and eyes. Exposure of eggs to 1 h of light during the dark period decreased the high melatonin concentrations in the eyes but not in the pineals of the 20-day-old chick embryo. The results suggest that in this precocial bird at least part of the circadian system may already operate during embryonic life.

Animals↗
PubMed1991

Regulation of cadmium induced porphyria by ascorbic acid in chick embryos.

Sublethal doses of cadmium chloride (2.5, 5.0 and 10.0 mu mole/kg egg weight) were found to significantly alter the first two rate limiting enzymes of heme biosynthesis in chick embryos. Delta-aminolevulinic acid synthase activity was elevated by 2.05 and 2.11 fold with 5.0 and 10.0 mu moles of cadmium treatment respectively. However, this was reduced to 1.25 and 1.3 fold by the simultaneous administration of ascorbic acid. Blood delta-aminolevulinic acid dehydratase (ALA-D) activity was decreased by 48.4 and 55.0 per cent with 5.0 and 10.0 mu moles cadmium treatment respectively; in the presence of ascorbic acid only 18 and 24 per cent inhibition of ALA-D activity was observed. Further 1.39 and 2.08 fold accumulation of delta-aminolevulinic acid and 4.17 and 4.62 fold increase of blood porphyrins was observed in chick embryos treated with 5.0 and 10.0 mu moles cadmium respectively. This elevation of intermediate compounds of heme biosynthesis was effectively checked by the administration of ascorbic acid. Depletion of hepatic heme and free sulfhydryl level by cadmium were countered by the treatment of ascorbic acid. Hence, the present findings suggest the protective role of ascorbic acid against cadmium induced chemical porphyria in chick embryos.

Animals↗
PubMed1962

Comparative studies in Rous sarcoma with virus, tumor cells, and chick embryo cells transformed in vitro by virus. II. Response of normal and immunized chicks.

Chick embryo fibroblasts infected in vitro with Rous sarcoma virus have properties similar to tumor cells when injected into virus-immune chickens. When such virus-transformed fibroblasts are injected into normal chickens, they apparently participate in the production of tumors independent of their release of virus and are thus apparently malignant in vivo.

Animals↗
PubMed1987

Toxic effects of phencyclidine on developing chick embryo brain.

We studied the effects of Phencyclidine (PCP, Angel Dust) on the developing chick embryo brain. In Group-1, the eggs were injected with PCP on the 7th day of incubation and the embryo brains were studied on the 10th day. In Group-2, eggs were injected twice; first on the 7th day and then on the 10th day of incubation. Group-2 brains were then studied on the 16th day of incubation. PCP significantly depressed the development of embryo brains. Cerebral hemisphere weight, total protein and total DNA were significantly lower on day 10 of incubation in Group-1. Similar results were observed in Group-2. Concomitantly, the concentration of brain serotonin at day 10 was also significantly reduced when PCP was injected into the eggs on the 7th day of incubation. Since serotonin has been reported to influence development of the chick embryo brain, the present finding of the effect of PCP on brain development might be a secondary phenomenon. The possible implications of the effects of PCP on human brain development are also discussed.

Animals↗