Evaluation of Ultrasonic-Range Vibratory Microinjection System at a Frequency of 35 kHz Using Fertilized Mouse Eggs

抄録

To facilitate pronuclear microinjection, we have been developing the Vibratory Microinjection Systems (VMSs) that provides a micropipette with longitudinal vibration. The current VMS utilizes any frequency up to 100 kHz. We compared 35-kHz vibratory microinjection (VM) with ordinary microinjection (OM). Fourteen micropipettes were used to inject 420 BDF1 zygotes. Each micropipette finished its injection quota of 30 eggs, which were manipulated one by one alternately using the two types of microinjections, even when it repeatedly pulled out nuclear components. All microinjections were conducted at a compensation pressure of 30 hPa and digitally recorded for subsequent image analysis. VM resulted in slightly better embryonic development in 4-day culture than OM, but significantly shortened the time spent on microinjection and the time spent swelling the pronucleus by 25% and 30%, respectively. These pronuclear swelling times, together with the almost identical degrees of pronuclear swelling in both groups, suggested that VM injected a GFP solution at a 42% higher speed. VM significantly reduced the incidence of pulling out nuclear components, suggesting VM’s capability of removing the nuclear components already adhering to the micropipettes. These results indicate VMS is a useful option which is capable of raising the efficiency of microinjection significantly by saving time, labor and cost of microinjection.