The generation time of two day chick neuroepithelial cells

Résumé Des études autoradiographiques effectuées sur les stades du cycle cellulaire dans les cellules neuroépithéliales de poulet de 2 jours, ont donné les résultats suivants: G2=1,5 h; M=1,0 h; S=6,5–6,8 h; G1=1,0–1,5 h et le temps de génération=10,0–10,8 h. On a également constaté que la thymidine H³ administrée à l'embryon comme dans l'expérience ci-dessus mit au moins 2 h à être incorporée.     

Possible involvement of calmodulin in apical constriction of neuroepithelial cells and elevation of neural folds in the chick

Chlorpromazine and trifluoperazine HCl, antipsychotic drugs known to bind to calmodulin, reversibly inhibited elevation of neural folds by interfering with the contractile activity of apical microfilament bundles in developing chick neuroepithelial cells.     

Possible involvement of calmodulin in apical constriction of neuroepithelial cells and elevation of neural folds in the chick

Summary Chlorpromazine and trifluoperazine HCl, antipsychotic drugs known to bind to calmodulin, reversibly inhibited elevation of neural folds by interfering with the contractile activity of apical microfilament bundles in developing chick neuroepithelial cells.We wish to thank C. Hess for her technical assistance. This study was supported in part by grants from the Busch Fund (Rutgers University), UMDNJ Foundation and Kapnek Fund.     

A transmission and scanning electron microscopic study of cytoplasmic threads of dividing neuroepithelial cells in early chick embryos

Summary Cytoplasmic threads found on the luminal surface of the developing chick neuroepithelium contain a remnant of the spindle complex and an electron-dense midbody. Most threads become long and thin and eventually split at the midbody. This finding suggests that the midbody plays a role in the final separation of daughter cells.This study was supported in part by grants from the Research Council and the Charles and Johanna Busch Memorial Fund of Rutgers University.     

Lipid droplets of neuroepithelial cells are a major calcium storage site during neural tube formation in chick and mouse embryos

In situ precipitation of calcium (Ca²⁺) with fluoride and antimonate shows that Ca²⁺-specific precipitate is localized almost exclusively within lipid droplets of neuroepithelial cells during neural tube formation in chick and mouse embryos. The density of Ca²⁺ precipitate within lipid droplets is generally greater in the apical ends of cells situated in regions of the neuroepithelium that are actively engaged in bending. These findings suggest that lipid droplets, in addition to providing a source of metabolic fuel for developing neuroepithelial cells, also serve as Ca²⁺-storage and-releasing sites during neurulation.This study was supported by grants from the NIH (NS23200), the BRSG fund of UMDNJ, and the Busch Fund of Rutgers University. Dr Bush was supported by a New Jersey State Postdoctoral Fellowship.     

Differentiation of chick embryo brain cells in culture

Résumé Des cellules, encore à un stade indifférencié, dissociées d'hémisphères cérébraux d'embryon de Poulet ont formé, en culture, des fibres nerveuses. La plupart des cellules se différencient en neuroblastes unipolaire et bipolaire; certaines évoluent vers le type multipolaire sans contact direct avec des cellules gliales.

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Chargée de Recherche au CNRS.     

Short axon ganglion cells in the chick retina

Summary Using Golgi's staining technique, we investigated some ganglion cells whose axons do not project out of the retina area. These axons, after following a short trajectory through the optic nerve fiber layer or through the 5th stratum of the inner plexiform layer (IPL), change their direction and end in the inner stratum of the IPL.     

Short axon ganglion cells in the chick retina

Using Golgi's staining technique, we investigated some ganglion cells whose axons do not project out of the retina area. These axons, after following a short trajectory through the optic nerve fiber layer or through the 5th stratum of the inner plexiform layer (IPL), change their direction and end in the inner stratum of the IPL.     

The inhibitory effect of D-glucosamine on thymidine kinase in chick embryo retinas and HeLa cells

D-Glucosamine markedly inhibits thymidine incorporation into the TCA-insoluble fraction and thymidine kinase activity in HeLa cells. Both the inhibitory effects are also observed in isolated retinas of chick embryos. In this case the inhibitory effects are age-dependent and the magnitude of the responses decreases with embryonic development. In addition the time of exposure to D-glucosamine which is necessary to reveal the inhibitory effect on thymidine kinase increases with the age of the embryos.     

The inhibitory effect of D-glucosamine on thymidine kinase in chick embryo retinas and HeLa cells

Summary D-Glucosamine markedly inhibits thymidine incorporation into the TCA-insoluble fraction and thymidine kinase activity in HeLa cells. Both the inhibitory effects are also observed in isolated retinas of chick embryos. In this case the inhibitory effects are age-dependent and the magnitude of the responses decreases with embryonic development. In addition the time of exposure to D-glucosamine which is necessary to reveal the inhibitory effect on thymidine kinase increases with the age of the embryos.     

Estrogen-induced phosvitin synthesis in cultured chick embryo liver cells

Riassunto È stata dimostrata la capacità di culture primarie di fegato embrionale di sintetizzare fosvitina in vitro dopo trattamento con estrogeni.