Successful fertilization and pregnancy following ICSI and electrical oocyte activation

Abstract

In a total of 1048 intracytoplasmic sperm injection (ICSI) cycles, motile spermatozoa from four out of 424 patients (0.9%) failed to fertilize oocytes, despite an apparently successful ICSI procedure. No activation was observed in these injected oocytes. The spermatozoa from three of the four patients were injected into unfertilized mouse oocytes by ICSI (mouse test) to evaluate their oocyte activating ability. The oocyte activation rate of the spermatozoa of patients A, B, and C in the mouse test was 46, 100, and 86% respectively (control: 100%). Simultaneous injection of two spermatozoa from patient A into the mouse oocytes increased the oocyte activating rate to 89% (sham control: 29%). 100% fertilization rates were obtained for patients A and B by combining ICSI and electrical stimulation, and this resulted in pregnancy and the birth of healthy twins for the partner of patient A. Thus, it is considered that the spermatozoa of these patients are not lacking sperm factors but that the activity of these factors is depressed. The combination of ICSI and electrical stimulation is effective in these cases.

How Long Do Parthenogenetically Activated Mouse Oocytes Maintain the Ability to Accept Sperm Nuclei as a Genetic Partner?

“…Another concern is the cytogenetic evaluation of embryos produced by applying artificial stimuli onto oocytes that are unfertilized after ICSI due to spermborne oocyte activation failure. An electrical stimulus applied after ICSI has delivered healthy twins (8). However, Tesarik et al (7) have reported that most human zygotes produced by treatment with the ionophore A23187 after ICSI undergo fragmentation during in vitro culture.…”

“…Electrical pulses after ICSI overcome sperm-borne oocyte activation failure and this procedure has resulted in the delivery of two healthy neonates (8). On the other hand, ICSI within a short time after parthenogenetic stimulation (post-activation ICSI) can also improve fertilization, because oocytes during meiosis II maintain the capability of transforming sperm nuclei to male pronuclei (9).…”

Intracytoplasmic Sperm Injection – Factors Affecting Fertilization

“…The failure of fertilization after ICSI may result from either the lack or deficiency of activating factors in sperm or from the lack of ooplasmic factors triggering sperm chromatin decondensation [79,80]. Several pieces of evidence point to PLCζ being the physiological agent of oocyte activation and is detectable in different localities within the sperm head: the equatorial segment and acrosomal/post-acrosomal region [81].…”

Analysis of clinical outcomes with respect to spermatozoan origin after artificial oocyte activation with a calcium ionophore

“…To rescue cases that encounter problems in oocyte activation immediately following sperm-oocyte fusion, certain artificial activation procedures have been recommended: mechanical activation by a modified ICSI technique [8,9], electrical activation [10,11], chemical compounds such as strontium chloride [12,13], ionomycin [14], and calcium ionophores [15], and sequential treatment with calcium ionophore and puromycin [16].…”