RNA biosynthesis during differentiation of various cell types of chicken embryo in cerebral hemispheres

Summary During the development of the chick embryo from the 6th to the 15th day of incubation, the cell types in cerebral hemispheres undergo differentiation. During this period the indifferent cells of the germinal layer migrate away from the neural cavity to form the mantle layer. These cells differentiate into neuroblasts and spongioblasts.RNA biosynthesis is very active in the cells of the germmal layer of the young embryos. From the 10th day on, it decreased becoming very weak in the 15-days old embryos. The RNA is stored in the nucleus and its passage to cytoplasm is very slow.In 6 and 8-days old embryos the RNA biosynthesis in the mantle layer is not very active but increases during embryonic development as the germinal cells differentiate. The biosynthesis is always more intense in the neuroblasts than in the spongioblasts. The RNA is stored in the nucleus and its passage to cytoplasm is slow in the young neuroblasts and the spongioblasts. The formation of Nissl bodies in neuroblasts and the differentiation of neuroblasts into neurons, which corresponds to the development of axons and dendrites, both are accompanied by an activation of the RNA passage from the nucleus into the cytoplasm.With the technical assistance of A. Brossard.