Pronuclear morphology predicts embryo development and chromosome constitution.
The relationship between pronuclear morphology on the one hand, and embryo development and chromosomal status on the other, was evaluated in 68 couples scheduled to undergo preimplantation genetic diagnosis because of advanced maternal age or recurrent implantation failure. Zygotes were grouped according to their pronuclear (PN) morphology. During the period from fertilization to embryo transfer, cleavage rate, embryo quality, blastocyst formation and results of the chromosomal analysis of 240 embryos were recorded. Both embryo cleavage characteristics and chromosome constitution were related to PN morphology. Embryos developing from zygotes with the normal PN pattern (pattern 0) cleaved faster and formed embryos with better morphology as compared with zygotes with abnormal PN patterns. Aneuploidy rate of embryos derived from zygotes with the normal PN pattern, with a single PN anomaly and with a double PN anomaly was 25.6, 73 and 83% respectively. Chromosomally normal embryos with the normal PN pattern progressed to the blastocyst stage at a higher rate (90%) than chromosomally normal embryos with a single (61%) or a double (40%) PN anomaly. The same relationship applied to chromosomally abnormal embryos. It is concluded that PN morphology predicts both the risk of embryo developmental arrest and that of chromosomal abnormalities.
Balaban
Basak
B
Assisted Reproduction Unit, American Hospital of Istanbul, Guzelbahce Sokak no. 20, Nisantasi/Istanbul, Turkey. basakbalaban@superonline.com
Yakin
Kayhan
K
Urman
Bulent
B
Isiklar
Aycan
A
Tesarik
Jan
J
D001755:Blastocyst / Q000166:cytology; D002455:Cell Division; D002869:Chromosome Aberrations; D005314:Embryonic and Fetal Development; D005260:Female; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D009865:Oocytes / Q000166:cytology; D010062:Ovulation Induction; D011237:Predictive Value of Tests; D011247:Pregnancy; D019836:Preimplantation Diagnosis / Q000379:methods*; D015053:Zygote / Q000648:ultrastructure*