A new approach to testing the effect of ultrasound on tissue growth and differentiation

Pulsed ultrasound from a Picker Ultrasonoscopy Model 102, with a frequency of 500 Hz and an energy of 2.2 MHz was applied to the amputated left forelimbs of 24 adult newts. Exposure time was 5 min in half of the animals and 10 min in the remainder. The right forelimbs of these newts were also amputated at the same time, at the same anatomical level, and by the same operator of the left forelimbs, but were not exposed to sonication. Regeneration of both forelimbs was compared and found to be generally slower in the ultrasonicated limb. In 75% there was a definite retardation of growth. The results suggest that the the growth of rapidly proliferating embryonic tissue (newt regenerates are formed from embryonic cells in the stump) is inhibited by ultrasonication.