Effects of underwater shock waves generated by pulse electric discharge on embryonic development of medaka

Shock waves have been used for various scientific, industrial, and medical applications. For example, underwater shock waves have been successfully applied for the fragmentation of urinary stones in urology. Further study on the influence of shock waves to tissues is required to extend medical shock wave application. Shock waves have been shown capable of affecting various cells. However, underwater shock wave application for modification of embryonic development remains unstudied. Therefore, this research investigates effects of underwater shock waves on embryonic development. Shock waves were generated by nanosecond pulse electric discharge via tungsten electrodes in a saline solution. A magnetic pulse compression circuit (MPC) was used as the power source. The generated shock waves were reflected by a reflector to produce a plane shock wave. They were applied to medaka (Japanese rice fish, Oryzias latipes) egg embryos (0 day and 2 days old eggs) through an experimental setup. The number of applied shock wave shots was 1, 5, 10, 50, and the range of the pressure value was from 19.5 MPa to 47.0 MPa. Effects of shock waves on embryonic development were observed using a fluorescent microscope. Increasing the number and the pressure value of shock waves was found to increase the extent of damage to the embryos. Egg abnormality appeared when moderate shock waves were applied.