The neural plate formation in chick embryo is due to a change in cell shape. The cubic cells (Plate I, fig. 1) become cylindrical (Plate II, fig. 3). Their adhesion increases and microtubules appear in the cytoplasm. The neural tube formation is due to the cells, which become bottle-shaped. These cells are linked at the surface of the neural plate by occludent junctions (Plate IV, fig. 8). The cells contract in the region where there are microfilaments between the junctions and expand at the opposite...
The metabolism of tritiated leucin has been studied in normal and Li-treated embryos of Xenopus laevis. The eggs were labelled by injecting tritiated leucin into the female toad during oogenesis. A decrease of the radioactive protein-bound leucin was observed during gastrulation. This decrease was more evident in ectoderm and mesoderm but less evident in entoderm (Table I, fig. 2). The loss of tritiated leucin from labelled proteins was greater in the control than in Li-treated embryos (Table I,...
Sodium thìocyanate action on the first stages of chick embryo: The early stages of chick embryos tolerate 0.005 M NaSCN. Acting during primitive streak formation (action in egg), this salt induces a certain number (about 17%) of embryos with enlarged notochord (fig. 1; Plate II, figs. 6, 7, 8, 9, 10, 11). Also the number of notochord cells increases (fig. 2). The volume of these cells is increased too. In some of these embryos with large notochord, the somites appear to be reduced in volume (Plate...
I somiti non si differenziano nell'espianto postnodale del blastoderma di pollo coltivato in vitro col metodo di New. Somiti si differenziano invece se al liquido di allevamento è aggiunto mRNA di miosina 26S estratto da muscoli di embrioni di pollo di 14 giorni. Lo stesso risultato si ottiene se il pezzo postnodale è coltivato in un pool di mRNA di muscolatura. Somiti sono anche indotti se al liquido di allevamento si aggiunge miosina. L'aggiunta di puromicina impedisce l'induzione di somiti per...
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