Rotationally oscillating drill (Ros‐Drill©) for mouse icsi without using mercury

Abstract

Intracytoplasmic sperm injection (ICSI) is an important assisted reproductive technology (ART). Due to deployment difficulties and low efficiency of the earlier (conventional) version of ICSI, especially in the mouse, a piezo-assisted ICSI technique had evolved as a popular ART methodology in recent years. An important and remaining problem with this technique, however, is that it requires small amounts of mercury to stabilize the pipette tip when piezoelectric force pulses are applied. To eliminate this problem we developed and tested a completely different and mercury-free technology, called the “Ros-Drill©” (rotationally oscillating drill). The technique uses microprocessor-controlled rotational oscillations on a spiked micropipette without mercury or piezo. Preliminary experimental results show that this new microinjection technology gives high survival rate (>70% of the injected oocytes) and fertilization rate (>80% of the survived oocytes), and blastocyst formation rates in early trials (~50% of the survived oocytes). Blastocysts created by Ros-Drill© ICSI were transferred into the uteruses of pseudopregnant surrogate mothers and healthy pups were born and weaned. The Ros-Drill© ICSI technique is automated and therefore; it requires a very short preliminary training for the specialists, as evidenced in many successful biological trials. These advantages of Ros-Drill© ICSI over conventional and piezo-assisted ICSI are clearly demonstrated and it appears to have resolved an important problem in reproductive biology.

Mechanism of Membrane Recovery in Intra-Cytoplasmic Sperm Injection

“…The main operational difference between piezo-drill and Ros-Drill is in the motion generation methods. Instead of the axial impact type action in the piezo-drill, the Ros-Drill rotationally oscillates the micropipette at a selected frequency and amplitude [21][22]. The intention for Ros-Drill design is that the ideal straight micropipette would rotationally oscillate about its axis without a lateral motion.…”

“…The intention for Ros-Drill design is that the ideal straight micropipette would rotationally oscillate about its axis without a lateral motion. However, the eccentricity in pipette due to manufacturing tolerance would generate some whirling motion during oscillation [21][22]. Therefore, the eccentricity level determines the unwanted lateral movement.…”

“…This Ros-Drill microinjector prototype employs a PLC (Programmable Logic Controller) as the digital controller, which has a maximum sampling frequency of 1 kHz [22]. This constraint limits the controllable trajectory to be at the maximum frequency of 500 Hz due to the Nyquist sampling rule.…”

“…A DC servo motor is employed to actuate the pipette to track a sinusoidal position reference. The servo motor comes with an optical encoder with 512 lines and quadrature signature capability which could only provide a sensor resolution of 0.176 [22].…”

“…Moreover, minimal demand on human expertise was claimed to be another benefit of this technology. These features result from the computer automated nature of the Ros-Drill technology as explained in the recent technology paper [21][22][23]. However, there is very few experimental or clinic data to support the statements and successful duplication by this method is necessary.…”