Simple method of calculating the average duration of mitosis by using a radiation method

On the mitotic index curve of the cellular population following radiation there is a linear part. The time interval between the initial decrease of the mitotic index and the extrapolation of the straight part of the curve to X-axes is the mean duration of mitosis. The values of this parameter for the culture of fibroblasts obtained by this method are practically identical with those obtained by a method based on determination of the mitotic index and the doubling time of the cell count.