RELATION BETWEEN CELL CYCLE AND YIELD OF ABERRATIONS OBSERVED IN IRRADIATED HUMAN LYMPHOCYTES

Abstract

The bromodeoxyuridine-Giemsa technique was used to systematically study the incidence of cells in 1st or subsequent motises at different fixation times of human lymphocyte control cultures and the influence of ionizing radiations on cell kinetics. Second divisions appear (3%) in cultures harvested 48 h after initiation. In 72 h cultures 40% of the dividing cells are in 2nd and 33% in 3rd division. Administration of 200 rads of X-rays before PHA [phytohemagglutinin] stimulation results in a mitotic delay but does not increase the incidence of SCE [sister chromatid exchanges]. The yield of dicentrics after an exposure to 200 rads was the same for all cells in 1st mitosis regardless of fixation time. There is no evidence for the existence of sensitive subpopulations that can be distinguished by the time of the 1st mitotic division following stimulation.