| Abstract: | A disordered somite pattern could be produced artificially when the segmental lateral plate of chick embryo was replaced by dissociated cells of quail segmental pate.The artificially disordered somite pattern formed at either place was used in our work as a model to analyze the mechanism of the development and differentiation of somite on chick embryo. Our conclusions include the following: 1.Although the formation of somites from the dissociated segmental plate cells does not require special environment,the development and differentiation of the somltes require a special environment which is related to the neural tube and notochord.The effect of this special environmental factor may decrease gradually with the increase of the distance from neural tube to lateral plate. 2.The somites located on paraxial area at different distances to the axis have different fates in development. 3.The formation of epithelial vesicles is the property of somite cells and the epithelial vesicle is the structural basis of somite differentiation.If and factor interferes with the differentiation of the somite,the epithelial vesicle of the somite will be degenerated within certain period of time. 4.During resegmentation of the somite,the number,size and arrangement of sclerotome in situ do not depend on the somite from which they are derived. 5.Somite cells do not transdifferentiate into kidney tubule directly from their original epithelial vesicles,but are reorganized from the free cells dispersed from the disrupted somites. 6.The establishment of cell commitment may involve several steps.Before commitment is established the of cell commitment is labile. 7.The differentiation of sclerotome starts with the rupture of epithelial wall of somites and the direction of its movement depends not only on the notochord but also on their position with respect to the neural tube and notochord. 8.The disordered somite pattern doesn't influence the segmentation of dorsal root ganglia in situ, but causes the formation of the ectopic dorsal root ganglia. |
