AUTORADIOGRAPHIC INVESTIGATION ON THE CELL KINETICS OF CRYPT EPITHELIA IN THE JEJUNUM OF THE MOUSE °CONFIRMATION OF STEADY STATE GROWTH WITH CONSTANT FREQUENCY DISTRIBUTION OF CELLS THROUGHOUT THE CYCLE

Abstract

Cell kinetic parameters of cells in the crypt of the jejunum of the mouse were obtained autoradiographically. A number of different methods used in cell proliferation studies were applied to the same animal strain kept under constant conditions. In order to avoid effects of geometrical factors, squashes of isolated crypts were used. The generation time was determined by the per cent labelled mitoses method of Quastler, modified by double labelling with 3 H‐ and 14 C‐TdR. This modified method permits a more exact determination of the generation time. The duration of the cycle was 14 hr. Double labelling experiments in which an injection of 3 H‐TdR was followed by an injection of 14 C‐TdR after 1 hr showed that the cell flux was 7.0%/hr at the beginning of the S‐phase and 7.68%/hr at the end. Assuming steady state growth a constant cell flux of 7.15%/hr within the whole cycle can be derived from the measured generation time of 14 hr. These results clearly show that the crypt epithelia constitute a steady state system with constant frequency distribution of the cells throughout the cycle. The per cent labelled mitoses method after a single injection of 3 H‐TdR as well as double labelling experiments with 3 H‐ and 14 C‐TdR give an estimate of the S‐phase of 8.0 or 7.4 hr respectively. Double determinations lead to a value of 0.54 or 0.52 hr respectively for the duration of mitosis and to values of 77% and 72%