The usefulness of a piezo-micromanipulator in intracytoplasmic sperm injection in humans

Abstract

Intracytoplasmic sperm injection (ICSI) has wide clinical application. In order to achieve good results with this method, it is important to restrict the possibility of oocyte injury as much as possible, and securely inject spermatozoa into the ooplasm. For this purpose, we clinically applied piezo-ICSI, which employs a micromanipulator with piezoelectric elements, to humans, and compared the results with those obtained by conventional ICSI. Conventional ICSI and piezo-ICSI were used in 279 cycles and 335 cycles respectively. Piezo-ICSI showed significantly more favourable results, with a survival rate of 88.1% (conventional ICSI: 81.4, P < 0.001), a fertilization rate of 79.4% (conventional ICSI: 66.4%, P < 0.001), and a pregnancy rate of 23.1% (conventional ICSI: 14.9%, P < 0.05). In piezo-ICSI, the needle used is not sharpened and has a flat tip. However, deformation of the oocyte during insertion of the needle is restrained by vibration of the piezo, and the oolemma is punctured readily and securely by the piezo pulse, at the site where the spermatozoon is injected. Piezo-ICSI is a promising new technique for human ICSI that should improve the survival, fertilization and pregnancy rates after ICSI.

Developmental competence in vivo and in vitro of in vitro-matured equine oocytes fertilized by intracytoplasmic sperm injection with fresh or frozen-thawed spermatozoa

“…Increases in efficiency have been reported in mice, humans and cows when ICSI using the Piezo drill was compared with conventional ICSI (Kimura and Yanagimachi, 1995;Yanagida et al, 1998;Katayose et al, 1999). Potential reasons for higher efficiency of Piezo microinjection include both increased damage and permeabilization of the sperm membrane, as mentioned above, and more reliable breakage of the oolemma, ensuring that the spermatozoa is deposited in the cytoplasm.…”

Dynamics of flagellar force generated by a hyperactivated spermatozoon

“…Furthermore, several recent studies examining the movement of the micropipette tip during the zona pellucida piercing in piezo-assisted ICSI revealed that not the longitudinal displacement of the micropipette tip but its transverse displacement was critical in piercing the zona pellucida (Ediz & Olgac 2004, 2005. Because the piezo-assisted ICSI resulted in a higher efficiency of microinjection even with a flat tip micropipette than the conventional ICSI in which the micropipette with a sharpened tip was rapidly pushed forward until it penetrated the zona pellucida (Kimura & Yanagimachi 1995, Yanagida et al 1998, the shear force generated by the lateral movement of the micropipette is probably more effective in piercing the zona pellucida than the propulsive thrust.…”

Estimating zona pellucida hardness under microinjection to assess oocyte/embryo quality: Analytical and experimental studies

“…In order to avoid these inadvertent consequences, several assisted ICSI/hatching techniques such as Piezoassisted ICSI (penetration of the ZP alone with a piezopulse to perform ICSI) [15,16] and laser-assisted ICSI (drilling a microhole through the ZP or thinning the ZP with a laser beam immediately prior to ICSI) [17][18][19][20] have been suggested.…”