[Kinetics of cell populations at various stages of the histogenesis of tissues of the chorioallantois of the chick embryo. Parameters of cell cycles].

By means of thymidine autoradiography, changes of the proliferative pool and those of the cellular cycle parameters have been studied in tissues of the chorioallantois and in the duodenal epithelium of the chick embryo at various stages of development. The decisive role in regulation of proliferation in the cell populations studied belongs to modifications of the proliferative pool.