The Value of Pronuclear Morphology as a Marker for Development and Competence of Embryo in ICSI Procedure

Original Article


Mohamed Danfour, Omar Elsraite, Mohamed Elmahaishi

Faculty of Medicine, 7th October University and Misurata Infertility Centre, Misurata Libya

JMJ 2009,Vol.9, No.1: 51-55


The relation between pronuclear zygote morphology and their fertilisation potential and embryo developmental competence after intracytoplasmic sperm injection (ICSI) is an important issue and has gained much attention recently due to its possible value in predicting implantation and pregnancy. This study was carried out to investigate a possible prognostic value of pronuclear morphology with four different pronuclear orientations on fertilisation rate and embryo quality. Methods: A total of 51 consecutive ICSI cycle (304 oocyte) was included in this study. All women were less than 40 years of age. All oocytes were cultured individually in order to follow their developmental potential. Embryo quality was assessed using both pre-embryo pronuclear morphology (zygote scoring or Z-scoring) at the time of fertilization evaluation and standard day 3 embryo morphology (number of blastomeres and grading based on degree of fragmentation and blastomere size). The main outcome measures were early cleavage rate, and quality of embryo. Results: The Z-score distribution of 276 embryo was 34.3% Z1, 26.4% Z2, 23.5% Z3, and 15.8% Z4. Significantly higher proportion of zygotes with Z1 and Z2 types of pronuclear orientation underwent early cleavage and developed into grade I embryos compared with other types (P < 0.001). Conclusions: Our results demonstrated that a combined evaluation of the Z-score and day 3 embryo morphology is highly predictive of embryo outcome after ICSI. The Z-score could be of great help in the selection of embryo for cultures extended to later stages or selection of embryo for freezing at 2PN stage. Also for determination of the most suitable embryo and the number of embryos for transfer, thus achieving the optimal chance of conception while reducing the risk of high order multiple pregnancy. Keywords: Embryo cleavage, Pronuclear morphology/zygote scoring. Link/DOI: