He-Ne laser light induced changes in the state of chromatin in human cells.

Cells of human buccal epithelium were irradiated in vitro by laser light at a wavelength of 632.8 nm and and an intensity of 1 mW/cm(2). The irradiation induced changes in the chromatin condensation state. The effect of irradiation depends on exposure time, and cells of different donors reveal varying sensitivity to laser light. In some donors 1 s exposure induced decondensation, but 2.5 min and 5 min condensation of chromatin in all donors.