The counting of cells and nuclei in microtome sections

A quantitative relation between the number of nuclei in a tissue and the number of nuclear fragments in its resultant microtome sections has been established by a new method. The general nature of the argument suggested that the correction procedure, although previously restricted to nuclei bounded by membranes, could be applied to mitotic figures and their fragments. With suitable interpretation this was found to be so, and numerical observations are presented which support this extension of the method. Depending upon their definitions, some of the various mitotic indices in use are theoretically subject to fragmentation error. This effect should be considered and only rejected, as in the example analysed, when it has been proved insignificant.