Predicted dose-latency relationships for early- and late-responding hierarchical tissues

By modelling a type H tissue whose structure and kinetics resemble the intestinal epithelium, the authors derived dose-latency curves typical in their time scales and dose-dependence of those of acutely responding tissues. By changing only the lifetime of cells in the functional compartment and the effect level at which tissue response occurs, dose-latency curves were obtained qualitatively similar to those of most late-responding tissues, with a marked dose-dependence in the lower range of doses at which endpoint occurs. The dose-latency relationship of the acutely responding tissue was affected most strongly by characteristics of the transit cells, while the dose-latency relationship of the late-responding tissue was influenced primarily by characteristics of the stem cells. Results indicate that the presence of a pronounced dose-dependence of the latent period should not be taken as evidence for a non-hierarchical type of tissue structure. (author)