Mitotic Indices of Human Bone Marrow Cells. II. The Use of Mitotic Indices for Estimation of Time Parameters of Proliferation in Serially Connected Multiplicative Cellular Compartments

Abstract

Abstract 1) The use and restrictions of mitotic indices in computations of time parameters in various types of mitotable cell compartments are discussed. Mitotic time must be known, and any death function in the mitotable pool must be assumed to be negligible. 2) The importance of the position of mitosis with respect to cytologic boundaries in computations of time parameters of mitotable cytologic compartments from mitotic indices is emphasized. 3) For detailed temporal analysis of catenated mitotable compartments, the parameter "turnover time" is shown to be inadequate. A new parameter, mean compartment transit time, is introduced. 4) In a catenated series of multiplicative cell compartments where the exact position of mitoses in the compartments is not known, precise compartment transit times cannot be calculated from mitotic index. However, the maximum mean transit time of each compartment can be computed from the number of cells in the compartment divided by the cell entry rate into the compartment, and the minimum mean transit time can be computed from the number of cells in the compartment divided by the cell exit rate. 5) Generation time can be calculated from mitotic indices only if it is possible to differentiate cell generations cytologically.