Behaviour in aggregates of irradiated imaginal disk cells ofDrosophila.

The ability of dissociated cells to reaggregate, grow in culture (in vivo) and differentiate cuticular structures following increasing doses of X-ray radiation has been studied.At low doses (up to 5 Kr) reaggregation, but not cell viability, is affected. The reaggregation ability of irradiated cells is improved with increasing time between irradiation and aggregation and can be rescued by mixing irradiated and non-irradiated cells.On the contrary, growth and cell differentiation seem to be cell autonomous events. At doses between 5 Kr and 8 Kr cell proliferation is impaired, and after doses over 10 Kr reaggregates show a "negative growth." The differentiation of cuticular structures, such as chaetes and trichomes, show a different X-ray sensitivity.A unifying interpretation of these results is outlined in the discussion.