In a Woman, Not all Oocytes the Same
Ability of sperm to bind to the zona pellucida varies from egg to egg, according to investigators.
The binding of the sperm to the zona pellucida varies from egg to egg within the same woman, even when the sperm source is unchanged, a study found.
“This is something that may be clinically significant and change the way some infertile couples are counseled, because to us it seems the numbers of the sperm binding to the zona may reflect the egg quality and maturity instead of the sperm quality,” said study investigator
Sperm binding within a single oocyte cohort was highly variable. The investigators theorize that this may be related to intrinsic factors of the egg, which could become better defined through their ongoing study.
“We are wondering if the degree of binding may be a good marker of oocyte maturity,” said Dr. Shen, who reported study findings at the annual meeting of the American Society for Reproductive Medicine in
“Just because a sperm is capable of binding, does not guarantee that it will. The role of the egg should not be underestimated in the binding process.” The ongoing study now includes assessment according to follicle size, in addition to egg maturity and/or fertilization outcome.
The investigators are tracking fertilized eggs until the day of transfer back to the uterus to further elucidate if the binding score itself may be a predictive marker of embryo quality. Most recent data suggest a strong correlation be-tween the binding score and embryo fragmentation on day 3 of in vitro culture. These findings are preliminary and will need to be replicated in a larger number of subjects.