Chromosome aberrations as a measure of mutagenesis: comparisons in vitro and in vivo and in somatic and germ cells.

Structural alterations to chromosomes constitute a significant portion of the genetic damage produced by most mutagenic agents. The pioneering experiments of Muller (1), in the case of ionizing radiations, and of Auerbach (2), in the case of nitrogen mustards, showed that chromosome aberrations are, quantitatively, a significant class of mutational events for both physical and chemical mutagens. The ultimate goal in any mutagen screening program is to be able to test potential mutagens directly on human genetic material or to extrapolate to man from other test systems with confidence. At present the easiest way to attain that goal is to use chromosomal aberrations as an index of mutational damage. It is quite simple to obtain a large number of homogeneous human cells, treat them with the agent in question, analyze the chromosomes at the subsequent mitosis, and, if desired, compare the results to identical studies done on other mammalian species. The technique employed in this instance