Effects of ultrasound on the prenatal development of the rat. Part 1. 3.2 MHz continuous wave at nine days of gestation.
Individual nine-day rat embryos were exposed for 5 or 15 minutes to graded intensities of well-characterized focused beams of 3.2 MHz continuous wave ultrasound. Fetuses were examined for effects at 20 days of gestation. Analysis of the exposure-response relationships indicates an "apparent threshold" for prenatal mortality at 3 W/cm2 (95 per cent fiducial limits 0.5-6 W/cm2). Fetal size was unaffected at any exposure level and there were only a few malformations, which occured at 10.5 W/cm2 and above.
D000818:Animals; D000013:Congenital Abnormalities / Q000209:etiology; D005260:Female; D005313:Fetal Death / Q000209:etiology; D005315:Fetal Diseases / Q000209:etiology; D005333:Fetus / Q000502:physiology*; D005865:Gestational Age; D011247:Pregnancy; D051381:Rats; D014465:Ultrasonics / Q000009:adverse effects*