Use of mouse oocytes to evaluate the ability of human sperm to activate oocytes after failure of activation by intracytoplasmic sperm injection

Abstract

The objective of the present study was to investigate the nuclei of human sperms that failed to fertilize human oocytes after intracytoplasmic sperm injection (ICSI). The sperms were injected into mouse oocytes by a piezo-micromanipulator, and some of these oocytes were artificially activated with strontium chloride (SrCl 2 ) after ICSI. The oocytes were fixed, stained, and subjected to chromosomal analysis. The survival rate of mouse oocytes injected with infertile human sperms was 92.0% (46/50), while that of the control mouse oocytes injected with fertile human sperms was 73.6% (81/110). The rate of two pronuclei (2PN) formation was 0 (0/46) by the infertile sperms and 81.5% (66/81) by the fertile ones, a significant difference ( p < 0.01). Sperm chromosomes in non-activated oocytes were present as premature chromosome condensation (PCC). Artificial activation after ICSI increased the 2PN formation rate in the infertile group to 90.3% (28/31). The results of the present study suggest that infertile sperms have a low potential to spontaneously activate oocytes and to form pronuclei. Thus, artificial activation after ICSI may rescue oocytes fertilized with infertile human sperms that do not produce 2PN. The present study proved the usefulness of mouse oocytes as specimens in evaluating the oocyte-activating capacity of objective human sperms prior to ICSI treatment.

Artificial oocyte activation in severe teratozoospermia undergoing intracytoplasmic sperm injection

“…Even though all the patients in this study were selected according to severity of abnormal morphology, the results of Figure 1 reveals that not all the patients may benefit from this artificial activation protocol. Therefore, diagnostic tests, like the mouse oocyte activation test, may be useful to evaluate activation potentials of a semen sample before assisted artificial oocyte activation in clinical settings (41,42). However, usage of the mouse oocyte activation test may be inconvenient in clinical settings, so other tests such as acrosome-related tests, like the gelationlysis test, may become useful or informative to assess integrity of acrosome, which may be related to sperm oocyte activation capacity (43,44).…”

Freezing-Free Preservation of Human Spermatozoa – A Pilot Study

“…For example, the ''hamster test'' was used to visualize human sperm chromosomes after IVF [Rudak et al 1978;Yanagimachi et al 1976] and provided insights into the frequency of structural sperm chromosome aberrations in infertile and fertile men [Martin et al 1983;Martin and Rademaker 1987;Moosani et al 1995;Rosenbusch et al 1992]. When ICSI became available, human spermatozoa unable to fertilize in vitro were injected into oocytes from other species [Araki et al 2004;Lee et al 1996;Rybouchkin et al 1995;Rybouchkin et al 1996;Terada et al 2004]. The ability to activate oocytes, from pronuclei, then condense into normal chromosomes was examined and subsequently used as a basis for recommendation for ART [Kim et al 2001;Nardo et al 2002;Zeyneloglu et al 2002].…”

rRNA Genes Are Not Fully Activated in Mouse Somatic Cell Nuclear Transfer Embryos

“…Generation of ICSI and NT Embryos-ICSI was carried out by a piezo-driven unit using the methods as described elsewhere (27,28), except that our experiment was performed in HEPES-CZB containing 5 g/ml cytochalasin B (Sigma, C6762) at room temperature (29). Only the sperm head was injected into oocyte.…”