The Mitotic Index and Interphase Processes

Abstract

1. Quantitative measurements of the amounts of material in a large number of individual cells are often presented as histograms, the forms of which are discussed. 2. It is shown that in a dividing tissue the rate of increase of the measured substance in a single cell may be derived from the histogram, provided certain assumptions hold. Appropriate formulae are presented. 3. The significance of the mitotic index in relation to interphase processes is also considered. It is concluded that the relation between the shape of a histogram and the mitotic index of the tissue cannot be defined unless the durations of interphase and mitosis and the proportion of cells participating in the interphase-mitotic cycle are known. 4. The difficulty of obtaining the latter information from any material other than tissue cultures is discussed.