Apoptosis in human cumulus cells in relation to zona pellucida thickness variation, maturation stage, and cleavage of the corresponding oocyte after intracytoplasmic sperm injection

OBJECTIVE: To assess the degree of apoptosis in the cumulus cells and the variation of the zona pellucida and the maturity and fertilization of the corresponding oocyte. DESIGN: Retrospective study. SETTING: Private fertility clinic. PATIENT(S): Fifty couples undergoing ICSI. INTERVENTION(S): ICSI. MAIN OUTCOME MEASURE(S): Correlation between apoptosis in the cumulus cells and the zona pellucida thickness variation, maturation stage, fertilization rate, and embryo score. RESULT(S): This study demonstrated no correlation between apoptosis in cumulus cells and the thickness and variation of the zona pellucida in oocytes and embryos. The incidence of apoptosis was significantly higher in cumulus cells from empty zona pellucidas and germinal vesicle stage and metaphase I oocytes compared with metaphase II oocytes. Non-fertilized metaphase II oocytes showed significantly higher incidence of apoptosis compared with fertilized metaphase II oocytes. There was a correlation between embryo score and the zona pellucida thickness variation. CONCLUSION(S): Apoptosis in cumulus cells had no impact on the zona pellucida thickness and variation in oocytes and embryos. The zona pellucida thickness variation was positively correlated to good embryo score. A higher degree of apoptosis was seen in cumulus cells from immature oocytes compared with mature oocytes. Furthermore, apoptosis in cumulus cells impaired the fertilization rate of metaphase II oocytes after ICSI.