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PubMedDate not supplied

[Activity of several erythrocyte enzymes in chick embryos and chicks after gamma-irradiation].

After irradiation of chick embryos and chicks (1,000 rad), the activity of some erythrocyte enzymes undergoes significant changes. During the 1st day after irradiation of chick embryos, the activity of lactate dehydrogenase leucine aminopeptidase and glutamate pyruvate transaminase decreases. At the 3rd day, the decrease in the activity of glucose-6-phosphate dehydrogenase and acid phosphatase is also observed. In irradiated chicks, the activity of lactate dehydrogenase, leucine aminopeptidase and aldolase decreases within the 1st and the 3rd days, the decrease being most significant for the former two enzymes. At later period (10 and 15 days after irradiation), most significant decrease was found in the activity of glucose-6-phosphate dehydrogenase. The activity of the same enzymes in the blood plasma of irradiated embryos and chicks increases, the increase being most evident for glucose-6-phosphate dehydrogenase.

Acid Phosphatase↗

PubMed1963

ACTINOMYCIN D: SPECIFIC INHIBITORY EFFECTS ON THE EXPLANTED CHICK EMBRYO.

Chick embryos containing 11 to 13 somites were cultured for 48 hours on media containing various amounts of the antibiotic actinomycin D. Morphological observations as well as quantitative determinations of protein nitrogen, DNA, and RNA indicate that the antibiotic specifically inhibits the growth and development of the embryonic axis posterior to the 12th somite.

Animals↗

PubMed1987

Role of vitamin D in the development of the chick embryo.

Chick embryos of various ages and 1-day-old chicks were injected with different doses of 1,25(OH)2D3 and the concentrations of Ca and Pi in their blood were determined 24 hr after. It was confirmed that the dose required to induce hypercalcemia and hypophosphatemia was much lower in the case of 15-day-old embryos than in younger ones. The age of maximal response corresponds to the period when the chorionic epithelium is fully differentiated. Newly hatched chicks did not respond even with doses 20 times higher than those used in 15-day-old embryos. These findings support the idea that the humoral changes produced by 1,25(OH)2D3 result from increased resorption of calcium from the shell and that the chorionic epithelium is instrumental in this phenomenon. The autoradiographic study of tissues from embryos injected with tritiated 1,25(OH)2D3 showed that the exposure time required to detect nuclear concentration of radioactivity was much shorter in the case of "villus-cavity" cells than in any other tissue (kidney, intestine, bone, parathyroid glands) in which target cells were recognized. The above results are interpreted as indicating that the chorionic epithelium is the main target for 1,25(OH)2D3. The histological study of various organs from embryos injected with large doses of 1,25(OH)2D3 showed generalized infiltration of spleen, liver, and bursa of Fabricius with eosinophilic granulocytes. It has been suggested that 1,25(OH)2D3 influences the proliferation and differentiation of leukocytes; the chick embryo might be a good model for further exploration of this problem.

Animals↗

PubMed1987

Effect of calcium supplementation on growth of shell-less cultured chick embryos.

Chick embryos grown in shell-less culture are calcium-deficient by 9 days and retarded in growth by 13 days of incubation (Dunn and Boone, Poult. Sci., 56:662-672, 1977). To determine whether addition of exogenous calcium might stimulate growth and/or survival of cultured embryos, calcium supplementation was attempted. Calcium supplementation between days 11 and 17 resulted in significant increases in both total embryo and serum calcium. Addition of shell pieces oriented with shell membranes onto the chorioallantoic membrane (CAM) resulted in significant stimulation of calcium transport by the CAM. However, growth of supplemented embryos was not increased to the same degree as were embryonic serum and total calcium levels. It is concluded that at least one factor other than calcium deficiency is responsible for retarded growth of shell-less cultured embryos.

Animals↗

PubMed1975

The effects of exogenous cortisone acetate on development (especially skeletal development) and on circulating levels of corticosteroids in chick embryos.

Chick embryos were treated with cortisone acetate on day 8 of incubation and the subsequent growth of the whole embryo and the development of the tibia studied to day 18 of incubation. Cortisone, at 10 ng to 2 mg/embryo decreased general body growth; above 0.5 mg/embryo it also retarded morphogenesis by as much as 3 Hamilton-Hamburger stages; and above 1 mg/embryo gross abnormalities were produced. The growth and differentiation of the tibia were affected to a greater extent than was the whole body. The reductions in tibial and total body weight were not linearly related to dose of cortisone injected. The exogenous cortisone acetate resulted in drastic alterations in the circulating levels of cortisone, cortisol, corticosterone, and progesterone, but plasma progesterone level was most readily correlated with the growth retardation. This study emphasizes that avian embryos can readily compensate for exogenous corticosteroids and that caution must be exercised when attributing causality to the substance administered.

Adrenal Cortex Hormones↗

PubMed1984

Centrifugation of 2 g does not affect otoconial mineralization in chick embryos.

Chick embryos were grown on a rotating centrifuge for periods of 2 wk to study the effects of increased gravity on the relative growth of their otoliths and femurs. Embryos, 20-21 days of age, centrifuged at 2 g showed no difference in utricular otoconial CaCO3 weights and femur CaPO4 weights compared with stationary control embryos of the same age. In addition, control embryos rotated at the center of the centrifuge had otoconial CaCO3 weights and femur CaPO4 weights not significantly different from stationary controls or from embryos rotated at 2 g. Accordingly these data do not support the hypothesis that the weight of the embryonic otoconial membrane is involved in the feedback regulation of its growth.

Animals↗

PubMed1983

Uptake and metabolism of [3H] pteroylglutamic acid by developing chick embryo.

Chick embryos at 9 and 12 days of development were injected into the air space with [3', 5', 7, 9 -3H]pteroylglutamic acid. After various time periods the incorporation of radioactivity into folate derivatives was measured. In the 9-day embryo the label incorporation into longer chain polyglutamates, expressed per gram, was higher than in the 12-day embryo. Since the endogenous content of these compounds was lower at 9 days, the results suggest that, at this stage of development, the turnover of longer pteroylpolyglutamates is more rapid.

Aging↗

PubMed1987

Ethyl alcohol-induced cardiovascular malformations in the chick embryo.

Chick embryos incubated for 72-80 hours were exposed to various volumes (0.20-0.40 m1/egg) of 50% ethyl alcohol. Examination of embryos at day 14 of incubation showed that higher doses of ethanol decreased the survival rate of embryos compared with control embryos. Three major categories of cardiovascular malformations were observed in this study: intracardiac anomalies characterized primarily by isolated ventricular septal defect, ventricular septal defect with overriding aorta, double outlet right ventricle or common aorticopulmonary trunk; aortic arch anomalies; and subclavian artery anomalies. Frequencies of embryos with intracardiac anomalies were equal to or greater than 64.8% in the six groups exposed to ethanol. Administration of ethanol also induced high frequencies of embryos with subclavian artery anomalies (11.2-89.1%). Absence or hypoplasia of the right and/or left secondary subclavian artery was commonly associated with persistence of the corresponding primary subclavian artery. Bilateral absence and/or hypoplasia of the secondary subclavian arteries was more common than unilateral anomalies, whereas absence of the left secondary subclavian artery was more commonly observed than an absent right secondary subclavian artery. No embryos in the two control groups combined (n = 94) demonstrated aortic arch or subclavian artery anomalies.

Abnormalities, Drug-Induced↗

PubMed1977

Inhibition of cranial neural crest cell development by vitamin A in the cultured chick embryo.

Chick embryos at stage 8, prior to neural crest cell migration, were explanted on whole egg medium with or without vitamin A and cultured for 3 days. Sections through the head regions showed that the cranial neural crest cells had migrated into the first visceral arch in the controls but were absent from this structure in the treated embryos. These observations suggest that vitamin A inhibits neural crest cell development or migration, an effect which may in part account for the facial malformations produced by excess vitamin A.

Animals↗

PubMed1975

Teratologic effects of LSD in explanted early chick embryos.

Chick embryos were explanted at stage; 4-7 and cultured for 20 h with or without LSD. At any stage 10 mug/ml LSD or higher caused abnormalities in axial structures, particularly somites, in over 50% of the embryos. LSD had no apparent effect on morphogenesis of the heart, but significantly lowered the pulse rate. Cellular degeneration occurred in severely affected structures, but LSD at embryotoxic doses caused alterations in neither cell morphology nor mitotic activity. The effects of LSD were not permanent, i.e., the embryos retained the ability to undergo normal morphogenesis when, after 4-5 h of treatment with 10 mug/ml LSD, they were subcultured on plain nutrient medium.

Abnormalities, Drug-Induced↗

PubMed1986

Effects of 100-Hz magnetic fields with various waveforms on the development of chick embryos.

Chick embryos were exposed during their 52 first hours of development to 100-Hz magnetic fields. Sinusoidal, square and pulsed waveforms were used at average field strengths from 0.1 A/m to 80 A/m. After exposure, the embryos were examined for abnormalities and classified by the developmental stages. When bipolar oscillations (oscillating at both sides of the zero-level) were used, the percentage of abnormal embryos was significantly increased above 1 A/m. In exposure to unipolar square waves, no significant effect on the percentage of abnormalities could be demonstrated. The developmental stage was possibly affected by unipolar square waves at 0.1 A/m, all other field strengths and waveforms being apparently ineffective.

Animals↗

PubMed1990

Effects of lithotripter fields on development of chick embryos.

Chick embryos at 72 h incubation were subjected to three double shock waves from a Wolf Model 2137.50 Electrohydraulic Lithotripter. The pressure amplitude at the embryo was adjusted by variation of the distance from the source to the embryo. After a total of 120 h of incubation, they were assessed for developmental abnormalities. Early deaths, delayed deaths and malformations were all significantly increased at pressures of 10 MPa with suggestions of possible effects at lower pressure levels.

Animals↗

PubMedDate not supplied

Ethanol exposure affects trophic factor activity and responsiveness in chick embryo.

Chick embryos were chronically exposed to either ethanol (approximately 30 mg/d) or saline, from E4-E13. Homogenate extract was prepared from forebrain tissue from E16 experimental and control embryos and was applied to cultured dorsal root ganglia (DRG). Neurotrophic activity in the forebrain extract (FBX) was significantly reduced in the ethanol-treated embryos compared to saline controls, both in terms of influences on neuronal survival and process elaboration. In addition, E8-9 DRGs from embryos exposed to ethanol from E4 were less viable in the presence of NGF than were those from controls. DRG survival in the presence of E16 FBX (from untreated embryos) was not different following ethanol treatment, but neurite production was significantly reduced. These results suggest that neurotrophic factor content and responsiveness may be appreciably altered following chronic prenatal ethanol exposure. Such alteration could underlie certain CNS anomalies seen in the fetal alcohol syndrome.

Animals↗

PubMed1983

The role of movements in the development of sutural and diarthrodial joints tested by long-term paralysis of chick embryos.

Chick embryos were paralysed in ovo with a neuromuscular blocking agent between 8 and 20 days of incubation. To evaluate the rôle of muscular activity in the development of sutural articulations, sutures of the cranial vault of control and paralysed embryos were studied histologically and the findings compared with the effect of the agent on the development of the ankle joint and some synovial joints of the jaws. Paralysed embryos showed a consistent lack of development of joint cavities in synovial joints. In most embryos, fusion of opposing cartilaginous elements had occurred. In contrast to synovial joints, sutural articulation showed a micromorphology comparable to that of controls. The findings indicate that different embryonic factors regulate the development of sutural and synovial articulations. Movements of neuromuscular origin play no essential role in the morphogenetic development of sutures, but are a prerequisite for the formation of joint cavities and other specialised structures of synovial joints.

Animals↗

PubMed1987

Monensin inhibits secretion of extracellular matrix and the spreading of mesoderm cells in the early chick embryo.

Chick embryos in culture were treated with the secretion-inhibiting ionophore monensin at the gastrulation stage of development. After treatment for 5 h at a concentration of 10(-5) M the embryos showed a drastic reduction in the tissue space between the upper and lower epithelia, and reduced spreading of the mesoderm cells that occupied this space. The basement membrane, to which many mesoderm cells are normally attached, showed varying degrees of disruption, which permitted blebbing of the overlying epithelium. Intracellularly, the treatment caused extensive vacuolization in all tissues. These results were consistent with the effects expected by removal of hyaluronic acid from the extracellular space, and this was confirmed by demonstrating a sharp reduction in glucosamine incorporation in this region. Examination of the effects of monensin on isolated mesoderm cells in culture using interference reflection microscopy indicated that the spreading of these cells was reduced independently of the changes in the extracellular matrix of the embryo. That this was probably due to the inhibition of cell surface fibronectin secretion was shown by demonstrating severe changes in the distribution of this glycoprotein using the immunofluorescent technique. It is concluded that the effects of monensin on this intact, developing system are due primarily to the disruption of hyaluronic acid secretion, but that disrupted fibronectin synthesis contributes to the reduced spreading of mesoderm cells.

Animals↗

PubMed1982

Organ growth in hyperoxic and hypoxic chick embryos.

Chick embryos and their organs were weighed in order to compare retarded growth with accelerated growth. Growth was quickened by incubating eggs in 60% O2/40% N2 and slowed by covering part of the shell of eggs incubated in air. A control group was incubated in air without any covering. At two-day intervals from the twelfth to the eighteenth days inclusive, eggs were opened and the embryos dissected and weighed. An organ was 'spared' if it differed from its control weight proportionately less than did the whole embryo. Covered eggs were opened only on the eighteenth day and showed sparing of brain and heart and hepatic stunting in excess of body stunting. Hyperoxic eggs spared brain and liver during the period in question, but the heart grew proportionately more than the other tissues between days 16 and 18. These data show that the availability of oxygen alters the rate of embryonic growth, and induces differential growth among individual organs.

Animals↗

PubMed1967

Bacterial interference in chick embryos.

Chick embryos infected intra-allantoically with nonvirulent staphylococci are protected from death due to infection with virulent staphylococci. The protection is associated with a delay in growth of the challenge strain and a delay in the production of toxic substances in the allantoic fluid. The protection is influenced by the number of bacteria in the protecting and challenge inocula and by the interval between the administration of the protecting and challenge strains. Protection cannot be transferred by administration of sterile filtrates of allantoic fluid in which the protecting strain has grown.

Animals↗

PubMed1993

Retinoic acid induces changes in the rhombencephalic neural crest cells migration and extracellular matrix composition in chick embryos.

Chick embryos at 9-10 stages (Hamburger and Hamilton: J Morphol 88:49-82, 1951) have been treated with all-trans retinoid acid (RA) (0.5 microgram, 1.5 micrograms, and 2.5 micrograms) to determine the pattern and mechanism of RA-induced effects on early cephalic development. We found that while 0.5 microgram RA did not produce any significant dysmorphogenesis, 2.5 micrograms RA elicited wide malformation of both cephalic and trunk regions. However, 1.5 micrograms RA produced selective and specific changes at the cephalic level, which consisted of morphological alterations, changes in neural crest cells (NCC) migration and extracellular matrix (ECM) composition. Morphological alterations included hypoplasia of the first three branchial arches, swelling of either anterior cardinal veins or dorsal aortae, and atrophy of branchial arch arteries. Concurrently NCC did not migrate away, remaining clustered on the dorsal surface of the rhombencephalon, and in some cases they shifted into the neural tube cavity. Accordingly, the second branchial arch showed a reduction of the mesenchymal cellular population. The extracellular matrix in RA-injected embryos showed changes in glycosaminoglycans (GAGs) concentration as compared with controls, that is, an increase in the non-sulphated GAGs, stained with alcian blue 8GX at 2.5 pH, and a decrease in the sulphated GAGs stained with alcian blue 8GX at 1 pH. These quantitative changes reflected alterations in the pattern of distribution and composition of the GAGs within the cephalic ECM, which specifically consisted in an increase of the hyaluronic acid and a decrease of the chondroitin sulphate. Our findings indicate that RA is involved in abnormal cephalic development, suggesting that RA may effect neural crest cell migration via changes in the GAGs of the ECM.

Animals↗