Ultrasound effects on cell proliferation and migration of chick motoneurons

The effect of ultrasound exposure on proliferation and migration of motoneurons was examined in chick embryos. Using an egg preparation which minimizes ultrasonic reflections and standing wave generation, chick embryos were exposed to ultrasound in ovo for 10 min at an intensity of 2 W/cm 2 Spatial Average, Temporal Average (SATA) with a frequency of 1.1 MHz pulsed at 2 kHz, and a pulse width of 75 μs. For cell proliferation studies, embryos were irradiated at the developmental stage of the most active lateral motoneuron proliferation. For cell migration studies, embryos were irradiated at the developmental stage just prior to lateral motoneuron migration. Our results show that the birthdates, migration and proliferation of lateral motoneurons are unaffected by the ultrasound exposure parameters used in this study.