Effects of diagnostic ultrasound irradiated during fetal stage on development of orienting behavior and reflex ontogeny in rats

The physical growth, the development of orienting behavior and neuromotor reflexes of offspring of rats that received an irradiation of a diagnostic level of ultrasound on the 9th day of gestation were estimated and compared with those of two control groups (untreated control and sham-irradiated or immobilized control). Results showed no significant group differences in terms of either physical development or development of orienting behavior. In the reflexological tests, however, a number of those reflexes that developed after 6 days of postnatal life of the offspring of irradiated rats showed significant delays in maturation when compared with those of the untreated control rats, but showed no difference from those of the sham-irradiated group. From these findings it is suggested that under certain circumstances such as in stress, the prenatally irradiated ultrasound of even a low-intensity may affect the development of the brain of offspring.