Quantitative analysis of the intensity of zona pellucida birefringence of oocytes during IVF cycles

Abstract

To determine whether the age of the female patient, oocyte maturation stage, pronuclei, embryonic quality and/or cycle outcome are related to the intensity of the zona pellucida birefringence (ZPB) in oocytes during IVF procedures, a retrospective study was conducted on 214 IVF cycles using a polarisation imaging system. A negative correlation was found between ZPB intensity and the age of female patients (r = –0.44; P < 0.0001). For oocytes at different maturation stages, the ZPB score was higher at the germinal vesicle stage (20.77 ± 1.88) than at MI (10.99 ± 1.35; P < 0.001), and higher at MI than at MII (7.91 ± 0.65; P < 0.05). For the pronuclei (PN) of fertilised oocytes, the ZPB score of oocytes with 3PN was significantly higher than that of oocytes with 1PN or 0PN (7.94 ± 0.78 v. 5.57 ± 1.51 and 4.45 ± 0.85, respectively; P < 0.001). However, there were no differences in ZPB scores between oocytes with 2PN and 3PN. Neither embryo quality on Day 3 nor the clinical results could be predicted on the basis of the ZPB score (P > 0.05).