[Effect of ultraviolet light on human chromosomes (author's transl)].

Lymphocytes were cultured in quartz flasks and irradiated by UV light. Time of exposure and moment of application varied. After UV treatment, pulverization of the chromosomes occurred and larger nuclear fragments which might be products of an abnormally proceeding mitosis with chromatin confluence were observed. The usual chromosome aberrations such as breaks, special segments, abnormal chromosomes and polyploidy have been rarely observed, but are found more often in those cultures where pulverization and nuclear fragments are less abundant. A number of mitoses in the irradiated cultures, however, shows no chromosomal aberrations. The ratio of unaffected to unaffected mitoses is dose-dependent. Chromosome fragmentation can result from UV irradiation occurring at any instance during the time of culture. One finds maximum and minimum amounts of damage when a constant dose is applied at various times.