Modelling of the influence of 3HTdR on cell kinetics in mouse epidermis

AbstractFluctuations occur in the labeling index (LI) of mouse epidermis over the first two days after application of tritiated thymidine (3HTdR) for which there has in the past been no explanation. Similarly, there has been no adequate explanation for the fluctuations in the percent labelled mitoses (PLM) data seen immediately after the first peak. Here we propose a model which provides an explanation for both these features. The hypothesis suggested is that some cells are killed by the 3HTdR either immediately when they are still in the S phase or later when they have reached G1. In both cases the labelled precursor is released from the cell and may be incorporated into other S phase cells after an appropriate delay. The model has been formulated into a computer programme which can derive the appropriate LI or PLM curves and fit curves to the relevant data. The resulting curves fit the data well suggesting that such cytotoxic and reutilization processes may in fact occur