Aging and sister chromatid exchange. VII. Effect of aging on background SCE in vivo

The frequency of background or spontaneous sister chromatid exchanges (SCE) was estimated in young and old rat and mouse bone marrow cell populations by exposing these cells to increasing concentrations of bromodeoxyuridine (BrdU). At the lowest levels of BrdU where SCE could be accurately assessed, there was no significant difference in background SCE between young and old cell populations. Extrapolation to zero BrdU concentration yielded SCE frequencies of approximately 1.0 SCE/cell/cell cycle in both mouse and rat cells.