赤松 信雄¹, 丹羽 国泰¹, 開場 香¹, 内海 恭三²

Nobuo AKAMATSU¹, Kuniyasu NIWA¹, Kaoru SEKIBA¹, Kyozo UTSUMI²

¹岡山大学医学部産科婦人科学教室, ²岡山大学農学部家畜繁殖学教室

¹Department of Obstetrics and Gynecology, Okayama University Medical School, ²Laboratory of Reproduction, School of Agriculture, Okayama University

キーワード : pulsed ultrasound, ultrasound, ultrasound irradiation effects, pre-implantation embryo, embryo

To elucidate irradiation effects of pulsed ultrasound on pre-implantation embryos and safety level of irradiated ultrasound intensity, we had performed irradiation experiments of pulsed ultrasound on pre-implantation embryos. The Wistar strain rat pre-implantation embryos, whose stages were late morula or early blastocyst, were located in the centre of ultrasound beam certainly by using closed microdroplet culture. Experiments were done in the degassed water at 37°C for 60 to 720 min. Irradiated ultrasound were pulsed one (carrier frequency; 2.0 MHz, pulse repetition frequency; 1000 Hz, width of pulse; 10 μs) and their spatial average temporal average (SaTa) intensities were 30 or 600 mW/cm² (spatial peak temporal peak intensity; 11 or 220 W/cm²).
The incidences of morphological abnormality and developmental retardation were increased when SaTa 600 mW/cm² pulsed ultrasound was irradiated for 720 min. So it was suggested that there was critical point of pulsed ultrasound irradiation at SaTa 600 mW/cm² for 720 min., but there was no significant increase.