Authors: Isaac C Wun, Yuh-Jue Chen, Chin-Hsuan Liu, Wan-Song Wun.
Abnormal fertilization is defined by more or less than 2 pronuclei (2PN) in human zygote, especially presence of 3 pronuclei. In this study, the incidence of abnormal fertilization was about 5% and related with maternal age and insemination method. The pronuclear number usually assumed corresponding to the ploidy number of zygotes. This study intended to examine the validity of the assumption. All preimplantation diagnosis cases with Fluorescent In Situ Hybridization (FISH) during 1/1/2004 to 7/31/2009 were included. A total of 497 ICSI cases with 3735 2PN embryos and 189 embryos with either more or less than 2PN were included. The ploidy of embryos was reflected from biopsied blastomeres with probes for chromosomes 13, 15, 16, 18, 21, 22, X, and Y. For embryos from 2PN zygotes, 67.3% were diploidy. For non-2PN group, 40% were diploidy. Except for the 2PN group, the chance of the number of pronucleus matching with the number of ploidies was less than 50%. The results show that the number of pronucleus is not full correspondent to the number of ploidy of embryos. One set of chromosomes can form more than 1 pronucleus. And 1 pronucleus can contain more than 1 set of chromosomes.
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