Our interest in modeling the process of cell growth and differentiation in cell culture systems was stimulated by in vitro experiments designed to study the growth and differentiation of bone marrow cells into mature macrophages and by attempts to maintain a line of macrophages in culture. When bone marrow or other not fully differentiated cells are grown on plates in the presence of nutrients and appropriate growth factors, some single cells grow into large groups of cells. Even when cells are grown under identical conditions, one finds great heterogeneity in the sizes of the resulting groups (see Fig. 1.1; also Fig. 1B of Sachs, 1987). As the length of time a plate is incubated increases, it is observed that the distribution of sizes of groups becomes bimodal (Stewart, 1980, 1984). Typically, groups are either relatively small (≤50 cells) and are called clusters, or are orders of magnitude larger than clusters and are called colonies. As the culturing time increases further, fewer groups fall between these size limits. Pharr et al. (1985) observed a similar bimodality in the colony size distribution of proliferating mast cells.
KeywordsStem Cell Mast Cell Colony Size Colony Growth Erythroid Progenitor
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