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Aim: It has been suggested that the position of the sperm after intracytoplasmic sperm injection (ICSI) has an effect on the development and quality of the embryo. In this study, we retrospectively examined whether pronucleus stage evaluation used through clinical studies in recent years has relevance with regard to sperm location. Methods: From 2003 to 2005, 1285 oocytes from 459 patients (average age: 36 years) were retrospectively analyzed. The 459 patients underwent ICSI because of fertilization disorders and oligozoospermia. Follicle stimulation was via either Clomid or the long protocol. Human chorionic gonadotropin was administered to induce ovulation and oocyte retrieval was conducted 35 h later. After confirming the presence of a polar body, we immobilized the ovum at the 6 o'clock position, introduced the injection pipette at the 3 o'clock position and carried out ICSI. Results: When a sperm was located at a position that was opposite to the polar body, both classifications of Scott and Tesarik regarding embryo quality were distinctly low. Furthermore, a good embryo classification ensued when the sperm was located adjacent to the polar body. Conclusion: The zone in which the sperm was located did not always correlate with embryo quality; however, our study suggested that sperm location affects the synchronization of the nucleolus. When carrying out ICSI, it is important to take into consideration the insertion point of the sperm. (Reprod Med Biol 2007; 6: 171-174).

Background : Intracytoplasmic sperm injection (ICSI) has risen to the forefront of reproductive technology. In the present study, the location of the sperm injection was noted, and a prospective study was conducted to evaluate the effect of the sperm retention site on cleavage rates and embryo quality after ICSI. Methods : This study involved 336 ICSI patients (age 27–44; average 37.4) where 1545 oocytes were observed. An oocyte was divided into nine sites and the sperm retention site was observed microscopically after injection. The polar body was placed at either the twelve or six o’clock position. The injection pipette was introduced at the three o’clock position and oolemma rupture was ascertained by mild suction. The main outcome measures were the relationship of sperm remaining in position in the oocyte to fertilization rate and embryo quality. Results : When the injection pipette was introduced at the three o’clock position, about 80% of the sperm remained in the center or left of center. The fertilization rate was significantly lower (p < 0.05) when the sperm remained near the site of introduction. Embryo quality was not significantly affected by the sperm retention site. Conclusions : About 12–14% of the spermatozoa remained near the introducing position, and in these cases the fertilization rate was low. However, once fertilization occurred, the sperm retention site had minimal impact on embryo quality. Injecting sperm near the spindle site may improve embryo quality.

Background Several parameters of early embryo development are known as predictors of implantation success. Recently, zygote or embryo morphological assessments are thought to be a major method of selection in embryo transfer. We expected that the concentrations of the steroids in follicular fluid (FF) were associated with oocyte maturation and embryo quality. In the present paper, we evaluated the relationship of several parameters.

The purpose of this study was to predict developmental competence of human oocytes during ICSI via analysis of connexin 43 (Cx43) in cumulus cells surrounding mature oocytes.Human cumulus cells were manually separated from the oocyte-cumulus complex under a microscope. Cx43 mRNA was expressed by real-time quantitative polymerase chain reaction (RT-PCR) measurement in cumulus cells.There was no significant relationship between expression of Cx43 and fertilisation or cleavage rate. However, Cx43 expression was lower in the good morphology group (blastomeres7 cells with fragmentation10% on day 3) when compared to the other groups (p=0.035).These results suggest that full reduction of Cx43 expression on cumulus cells at the time of oocyte collection during ICSI is essential for developmental competence of human oocytes.

Summary Successful fertilization using intracytoplasmic sperm injection (ICSI) was first reported in 1988 and the first successful ICSI pregnancy was in 1992. Since then, this technology has quickly become an indispensable technique in reproductive medicine, and its validity has been verified through several clinical studies over the past 10 years. After several technologic improvements, the rate of ICSI fertilization is comparable to that of conventional in vitro fertilization. In this article, we discuss how ICSI has improved fertilization and pregnancy rates.