Cytogenetics of uncleaved oocytes and arrested zygotes in IVF programs.

PURPOSE

Cytogenetic studies of arrested oocytes and zygotes were used to understand in vitro fertilization (IVF) failures.

METHODS

We investigated the cytogenetics (Giemsa banding and FISH) of 710 uncleaved oocytes and 94 arrested zygotes from 208 patients undergoing IVF procedures.

RESULTS AND CONCLUSIONS

Of uncleaved oocytes without a polar body, 39% were judged cytogenetically abnormal (17% unbalanced predivision and 21.5% diploid). Of 575 oocytes with a polar body, 124 (21.5%) showed numerical or structural chromosome aberrations. In arrested zygotes, approximately equal cases were found with separate condensed haploid complements (no syngamy), nuclear asynchrony and pulverized DNA, and apparently cytogenetically normal zygotes arrested at mitosis. These data on chromosome abnormalities were also analyzed with respect to two ovarian stimulation protocols and to maternal age. Both ovarian stimulation protocols and to maternal age. Both ovarian stimulation protocols showed the same levels of chromosome abnormalities. Overall chromosome abnormalities and premature chromosome condensation were also unchanged with maternal age. These data illustrate the significance of chromosome aberrations in IVF failures.