Mercury-free mouse ICSI with rotationally oscillating drill (Ros-Drill<sup>©</sup>)

Abstract

ICSI (intracytoplasmic sperm injection) is an important and commonly used assisted reproductive technology (ART) in humans and animals. However, conventional ICSI has proven to be difficult and inefficient, especially in mice. Fortunately, the application of piezo-electric technology to assist the injection process has made ICSI more effective and efficient in recent years. Despite this advance, the pipette tip is unstable in response to the force exerted by the piezoelectric pulse during injection. To some extent, this instability can be mitigated by the use of mercury, which is highly toxic. In an effort to overcome these hurdles, we developed and tested a completely different and mercury-free technology, called the “Ros-Drill©” (rotationally oscillating drill), which uses a microprocessor-controlled actuator to generate rotational oscillations on a spiked micropipette. ICSI utilizing the Ros-Drill© requires neither mercury nor piezoelectricity. Early experimental trials reveal high survival (≫70% of the injected oocytes), fertilization (≫ 80% of the survived oocytes), and blastocyst formation rates (∼ 50% of the survived oocytes). After surgical transfer of blastocysts created by Ros-Drill© ICSI into pseudopregnant surrogate mothers, healthy pups were born and weaned. Because the Ros-Drill ICSI technique is automated, a very short training period is required, especially for specialists. These studies in mice have revealed, that Ros-Drill ICSI has mentioned advantages over conventional and piezo-assisted ICSI starting with the elimination of mercury in the process.