The effect of 5-bromodeoxyuridine on mouse embryos during neurulation in vitro

Mouse embryos explanted at various stages during neurulation were cultured for 20-28 h in the presence of 25-900 micrograms/ml of 5-bromodeoxyuridine (BUdR). BUdR strongly inhibited closure of the cranial neural tube, which was found to be stage-dependent. When mouse embryos were exposed to BUdR after development of the concave curvature in the neuroepithelium of the midbrain to the upper hindbrain regions, they became insensitive to the drug-induced open cranial neural tube. Histological observations showed that BUdR interfered with interkinetic migration and cytokinesis of the neuroepithelial cells. These cellular abnormalities were not dependent on the morphological development of the cranial neural folds. The 3H-BUdR experiment confirmed that the label was mostly incorporated into the DNA fraction.     

The effect of 5-bromodeoxyuridine on mouse embryos during neurulation in vitro

Summary Mouse embryos explanted at various stages during neurulation were cultured for 20–28 h in the presence of 25–900 g/ml of 5-bromodeoxyuridine (BUdR). BUdR strongly inhibited closure of the cranial neural tube, which was found to be stage-dependent. When mouse embryos were exposed to BUdR after development of the concave curvature in the neuroepithelium of the midbrain to the upper hindbrain regions, they became insensitive to the drug-induced open cranial neural tube. Histological observations showed that BUdR interfered with interkinetic migration and cytokinesis of the neuroepithelial cells. These cellular abnormalities were not dependent on the morphological development of the cranial neural folds. The³H-BUdR experiment confirmed that the label was mostly incorporated into the DNA fraction.Acknowledgment. This work was supported by Grant-in-Aids for scientific research No. 557469 and 58480391 from the Ministry of Education, Japan.     

Effects of 5-bromodeoxyuridine on in vitro development of mouse embryos in the early somitic stage

Summary The inhibitory effect of 5-bromodeoxyuridine on the early somitic stages of mouse embryos was largely prevented in the presence of excess thymidine but only partially prevented by deoxycytidine.     

Inhibition and stimulation by 5-bromodeoxyuridine of erythropoiesis by chick blood island cells

Summary Erythropoiesis in liquid cultures of cell populations resolved from chick blastodiscs at the primitive streak and head-fold stages was totally inhibited by 5–8 g/ml of 5-bromodeoxyuridine. However, concentrations of 0.2 /ml of the nucleoside enhanced the number of erythroid cells formed.This work was supported by grants from the Medical Research Council and National Research Council of Canada. We thank MissesK. Beall andN. N. McGrath for technical assistance. S. D. W. is an Associate of the Medical Research Council.     

Distribution of S35-sodium sulfate in early chick embryos

Résumé La distribution du radiosulfate introduit dans les embryons de poulet de 3 jusqu'à 7 jours a été étudiée par l'autoradiographie de contraste. Il existe des différences marquées dans la fixation du S³⁵ au niveau des ébauches d'organes différents et même dans les diverses parties de chaque tissu. Ces différences sont particulièrement remarquables entre les divers dérivés du mésoderme et elles s'accentuent pendant la différenciation ultérieure.     

Incorporation of 5-bromodeoxyuridine in the total and ribosomal DNA of synchronously dividing chick embryo fibroblasts

The pattern of 5-bromodeoxyuridine incorporation into ribosomal DNA is quantitatively different from that for total DNA. It is concluded that 5-bromodeoxyuridine incorporation along the DNA chain is not a random process.     

Application of chemicals in early chick embryos in ovo: A precaution

Summary A passive diffusion method is described and is compared with other methods for the application of chemicals in early chick embryos in ovo.Acknowledgments. We thank Mrs Irene Panagopoulou for expert technical assistance.     

Some new data concerning effect of actinomycin D on early chick embryos

Zusammenfassung Actinomycin D führte beim Hühnerembryo zu einer deutlichen Hemmung der Herzentwicklung nach Inkubation im Nährmedium während der Entwicklungsstadien 3 und 3⁺. Nach Vorbehandlung der Stadien 3–7 und anschliessender Kultur in actinomycin D-freiem Medium fanden sich Fehlbildungen von Herz, ZNS und Somiten, die in ihrer Häufigkeit von den betroffenen Entwicklungsphasen abhängig sind.

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This study was supported by a grant from the Rutgers University Research Council No. 07-2189.     

Toxicity ofPhytophthora infestans andAlternaria solani to chick embryos

Summary None of the extracts and culture filtrates from growth of 9 races ofPhytophthora infestans on living potato tissue and potato dextrose broth are toxic to chick embryos. Chloroform extracts of 4 out of 10 isolates ofAlternaria solani grown on potato dextrose broth showed some toxicity to chick embryos.Acknowledgment. This research was supported by grant FD-00683-03 from the Office of Research Grants, Food and Drug Administration.     

Toxicity of Phytophthora infestans and Alternaria solani to chick embryos

None of the extracts and culture filtrates from growth of 9 races of Phytophthora infestans on living potato tissue and potato dextrose broth are toxic to chick embryos. Chloroform extracts of 4 out of 10 isolates of Alternaria solani grown on potato dextrose broth showed some toxicity to chick embryos.     

Isolation of intracellular yolk granules in early chick embryos and estimation of their DNA content

Zusammenfassung Nachweis, dass der DNS-Gehalt der Dottergranula in Hühnerembryonalzellen in der frühesten Entwicklungsperiode (0–18 h) temporär ansteigt.

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The scanning electron microscope was made available by Analytica, Sollentuna and the scanning micrograph was taken by Mr.G. Alsterborg.

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This work has been supported by the Swedish Natural Science Research Council (H.E.) and Kungliga Fysiografiska Sällskapet, Lund.     

Further studies on neural tube defects caused by concanavalin A in early chick embryos

Summary Neural tube defects caused by concanavalin A in chick embryos are consequences of change in the cell surface of developing neuroepithelium.This study was supported in part by grants from the Rutgers University Research Council.     

Biosynthesis of ascorbic acid in chick embryos

Biosynthesis of ascorbic acid was found in the kidneys (mesonephros and metanephros) of the chick embryo as well as in the yolk sac membrane. The activity of L-gulonolactone oxidase in the yolk sac membrane suggested that it was the major source of ascorbic acid in the chick embryo.     

Biosynthesis of ascorbic acid in chick embryos

Summary Biosynthesis of ascorbic acid was found in the kidneys (mesonephros and metanephros) of the chick embryo as well as in the yolk sac membrane. The activity of L-gulonolactone oxidase in the yolk sac membrane suggested that it was the major source of ascorbic acid in the chick embryo.I am grateful to Dr R. Jenness (Univ. of Minnesota) for the generous gift of L-gulonolactone and to Dr B. Sanders (Univ. of Texas) for the chick embryo samples