[Changes in the number of sister chromatid exchanges in cultured Chinese hamster cells with limited proliferation. Additional studies]

During "stationary phase ageing" of cultured Chinese hamster cells (B11dii-FAF28 line, 2372a clone), i. e. while decreasing the proliferation rate and in the stationary growth phase the frequency of spontaneous sister chromatid exchanges (SCE) progressively increases (from 2- to 23-day "age"); the frequency of thiophosphamide-induced (1h) SCE increases from 2- to 23-day "age" by the same value as the frequency of spontaneous SCE; the cells deepen into the R-phase of the cell cycle.