Low doses of pulsed ultrasound and chromosomal abnormalities in male mouse germ cells

Male mice were exposed to pulsed ultrasound (intensity <1mW, frequency 3.5 MHz) for 30 min or to sham treatment. After30 h, 11, 12 or 13 days, the testes were cytologically and histologicallyexamined (using squash preparations, air-drying and sections).The resulting damage was studied at diakinesis—metaphaseI and II, spermatogonial metaphase and anaphase. The investigationby air-drying did not show any significant increase in chromosomedamage, 30 h, 11, 12 and 13 days after treatment (spermatogonialand spermatocytic metaphases). There was, however, a significantincrease of the frequency of aneuploid cells detected at metaphaseII. Investigations by squash techniques or sections did notreveal adverse effects on the spindles at spermatogonial andspermatocytic anaphases. We suggest that the reduction of fertilitypreviously observed in our clinic could be explained by an increaseof aneuploidy if germ cells are exposed to ultrasound duringdiakinesis of the first meiotic division.