Sister chromatid exchanges in mouse after exposure to pulse-wave ultrasound in utero.

The induction of sister chromatid exchanges (SCEs) was investigated in mice after a ten min exposure, in vivo, to 2 MHz focused, pulse-wave ultrasound with a pulse repetition rate of 1000 Hz, pulse duration of 10 microseconds. The bone marrow cells of the pregnant female mice and the fetal liver cells were analyzed. The cell cycle specific metaphase patterns were additionally evaluated. In the bone marrow cells, the mean frequencies of SCEs were 2.77 in control, 3.56 in the cells exposed to ultrasound at 586.2 mW/cm2 (spatial average temporal average, SATA); in the fetal liver cells, 2.64 in control, 3.84 in the cells exposed. The frequencies of SCEs significantly were increased by the treatment. Faster cell kinetics was observed in fetal liver cells than bone marrow cells of pregnant female. But there was no cell-growth inhibitory effect of ultrasound on both bone marrow and fetal liver cells. In fetal liver cells, the critical acoustic power was 160.0-278.9 mW/cm2 (SATA).