[Kinetics of cellular populations at different stages of the histogenesis of tissues of the chorio-allantois of the chick embryo].

Changes occurring in indices of cell fractions being at the phase of mitosis (Nm) and at the phase of DNA synthesis (NS) have been studied in the chorio-allantoic tissues and in epithelii of the duodenum and cloaca. Their dynamics differ essentially. In the chorio-allantois, decrease in the Nm up to the 14th day is evidently connected with the transfer of the cells into R2-state, and then decrease of the proliferative pool takes place. This is caused by outcome of the cells from the reproductive cycle into differentiation.