Cell proliferation and chromosomal damage in human leukocytes: dicentrics and premature chromosome condensations in first, second, and third mitoses after X-irradiation.

The frequencies of dicentric chromosomes and of partial premature chromosome condensation (PCC) in definitely first, second, or third mitoses after X-irradiation of human leukocytes, as determined with a bromodeoxyuridine (BUdR)/ Giemsa labeling technique, were investigated. The results show that practically no PCCs occur in first mitoses after irradiation and culture start in contrast to second or third ones. The frequencies of dicentrics from first to second, as well as from second to third mitoses after irradiation decline by about 50% for each division step.