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Updated: Aug 19, 2026

Human Egg Maturity Assessment and Its Clinical Application
Published on: August 19, 2019
High magnitude of light retardation by the zona pellucida is associated with conception cycles
1Centre of In-Vitro-Fertilisation (CIF) in Justus-Liebig-University, D-35392 Giessen, Germany.
Background:
Failures in expression of zona proteins correlate to subfertility in animals. Low expression of the zona proteins by the growing human oocyte may indicate reduced developmental potential. Therefore, we non-invasively analysed the thickness and the structure of the zona pellucida (ZP) of human oocytes with respect to embryo fate after ICSI.
Methods:
Retardance magnitude and thickness of the inner, middle and outer layers of the ZP were quantitatively analysed by a Polscope in 166 oocytes selected for transfer after ICSI (63 patients; 32.8 +/- 4.4 years) on the basis of pronuclear score at day 1. Blastomere number was determined at day 2. Data were compared between conception cycles (CC; 65 oocytes/23 patients) and non-conception cycles (NCC; 101 oocytes/40 patients) and with respect to maternal age.
Results:
The thickness was slightly elevated (P < 0.001), and the mean magnitude of light retardance was nearly 30% higher (P < 0.001) in the inner layer of the zona pellucida of oocytes contributing to CC compared to NCC. Embryos in the CC group tended to develop faster.
Conclusions:
The magnitude of light retardance by the zona pellucida inner layer appears to present a unique non-invasive marker for oocyte developmental potential.
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