Cell cycle parameters and proliferative activity in chorioallantois tissues at various stages in chick embryo development

: Two peculiarities of cell population kinetics are characteristic of the provisional tissues of the chick embryo chorioallantois. The one is that the proliferative pool is relatively small at relatively early stages of embryogenesis (8 day incubation). The other is that at the final stages of embryogenesis, when proliferative activity in the embryo cell populations is still high, the cell reproduction is practically stopped. The process of tissue differentiation in chorioallantois, on the one hand, is accompanied with a withdrawal of a considerable part of cells from the cycle of reproduction, but on the other hand this differentiation affects the cells that have remained in the proliferative compartment which is reflected in modifications of either the cell cycle structure or the cell population composition.