Vacuolization in embryos on days 3 and 4 of in vitro development: Association with stimulation protocols, embryo development, chromosomal status, pregnancy and neonatal outcomes

Abstract

Study questionIs vacuolization in embryos on Days 3 and 4 associated with parent-related factors, stimulation protocols, embryo development, embryo ploidy, pregnancy and neonatal outcomes?Study design, size, durationThis is a retrospective cohort study that comprised 5,703 embryos from 611 patients who underwent preimplantation genetic testing and time-lapse monitoring of their embryos from August 2017 to September 2021.Main resultsEmbryo vacuolization on Days 3 and 4 is associated with the LH level on the day of the hCG trigger and the number of retrieved oocytes. Compared to vacuole-negative embryos, the rates of blastocyst formation and good-blastocyst formation was significantly lower in vacuole-positive embryos. We observed no significant difference in the rates of euploidy, implantation, ongoing pregnancy, and live birth between vacuole-positive and vacuole-negative embryos. In vacuole-positive embryos, the embryos of which the vacuole-positive blastomeres were involved in embryo compaction exhibited significantly higher mosaicism rate compared with those of which the vacuole-positive blastomeres were not involved in embryo compaction.ConclusionVacuolization in embryos on Days 3 and 4 is associated with reduced blastocyst formation rate and high-quality blastocyst rate. Blastocysts had a low mosaicism rate if the vacuole-containing cells were rejected in compaction process, which supports the hypothesis that exclusion of abnormal blastomeres from compaction is a self-correction mechanism.

CX43 and oxidative stress are the targets of BCB staining to predict the developmental potential of buffalo oocytes

“…Now most oocytes in vitro are screened by morphological standards, and the quality of oocytes is judged by the number and compactness of cumulus cells wrapped on oocytes, the color and uniformity of oocyte cytoplasm (2). However, morphological standards have shortcomings such as inaccuracy, experience dependence and strong subjectivity, which limit the selection of high-quality oocytes (3). In recent years, a new, non-toxic method -Brilliant cresyl blue (BCB) staining has been successfully applied to the screening of oocytes from various animals(4-8).…”