A POSSIBLE INTERPRETATION OF SOME COLONY-FORMING ASSAYS - DEVELOPMENTAL TREE MODEL

The characteristic form of the probability distributions of in vitro g rown colonies is analysed and experimental results are shown to be wel l approximated by an exponential dependence. It is argued that this ty pe of dependence is very frequent in nature and does not provide suffi cient evidence to resolve the dilemma whether the development of haemo poietic lineages proceeds according to a schema of 'progressive and st ochastic restriction' or more limiting 'developmental tree' with some random control process involved. Detailed analysis of the experimental conditions and results is needed to provide insight into collective p henomena in cellular proliferation and differentiation. At present, th e complexity of the phenomena involved prevents unique interpretation of the experimental distributions. Nevertheless, one particular quanti tative model, based on a developmental tree concept, yields a set of t he theoretical probability distributions, which are in a very good agr eement with the experimental results.