title: Cell population dynamics during the differentiative phase of tissue development.
abstract: The dynamics of a cell population whose numbers are growing exponentially have been described well by a mathematical model based on the theory of age-dependent branching processes. Such a model, however, does not cover the period following exponential growth when cell differentiation curtails population size. This paper offers an extension to the branching process model to remedy this deficiency. The extended model is ideal for describing embryonic growth; its use is illustrated with data from embryonic retina. The model offers a better computational framework for the interpretation of a variety of data (growth curves of cell numbers, DNA histograms, thymidine labelling indices, FLM curves, BUdR-labelled mitoses curves) because age-distributions can be calculated at any stage of development, not just during exponential growth. Proportions of cells in the various phases of the cell cycle can be computed as growth slows. Such calculations show the gradual transition from a population dominated by cells which are young with respect to cell cycle age to one dominated by those which are old, and the effects such biases have on the proportions of cells in each phase.
mesh_terms: D000367:Age Factors; D000818:Animals; D002452:Cell Count; D002453:Cell Cycle; D002454:Cell Differentiation; D002642:Chick Embryo; D003201:Computers; D007399:Interphase; D008433:Mathematics; D008954:Models, Biological; D011336:Probability; D012160:Retina / Q000166:cytology; D012984:Software