Abstract
The frequencies and distributions of sister chromatid exchanges and chromosomal aberrations induced by 5-fluorodeoxyuridine and ethyl methanesulfonate on cultured Chinese hamster cells were investigated. The distributions of sister chromatid exchanges and chromosomal aberrations induced by both agents in the early S phase were entirely different. Sister chromatid exchanges were distributed uniformly at a relatively higher incidence in the euchromatic regions, whereas chromosomal aberrations were more frequ-ent in heterochromatin. Combined treatment with 5-fluorodeoxyuridine and ethyl methanesulfonate significantly enhanced the frequency of sister chromatid exchanges without changing their distribution along the length of the chromosome.
