Exposure to Bisphenol-A Affects Bovine Oocyte Spindle Morphology and Chromosome Alignment

Bisphenol-A (BPA) is an endocrine disrupting chemical (EDC) frequently used in the production of plastics. BPA has been detected in various human tissues and fluids, including the follicular fluid that surrounds the oocyte... [ view full abstract ]

Bisphenol-A (BPA) is an endocrine disrupting chemical (EDC) frequently used in the production of plastics. BPA has been detected in various human tissues and fluids, including the follicular fluid that surrounds the oocyte (immature egg cell) within the ovary. Exposure of the oocyte to BPA has been associated with disturbed reproductive health conditions, including abnormalities in meiosis that may contribute to infertility. We investigated the hypothesis that BPA exposure during oocyte maturation would disrupt meiotic progression, spindle morphology and chromosome alignment. Bovine oocytes were matured in vitro in the presence or absence of a range of BPA concentrations. Meiotic progression, spindle morphology and chromosome alignment were analyzed using immunocytochemistry and fluorescence microscopy. Our data suggest that BPA does not affect the proportion of oocytes that progress to metaphase-II. Exposure to some of the BPA concentrations increased the proportion of oocytes with spindle abnormalities and misaligned chromosomes while an intermediate dose had no effect, suggesting a non-linear relationship between BPA concentration and these parameters. The concentrations of BPA that caused abnormalities in spindle morphology and chromosome alignment are at or below levels measured in human follicular fluid; therefore these findings raise concerns about the effects of BPA on human fertility. This research was supported by NIH 1R15ES024520-01 (CC) and in part by the Biology Department and SRPS funding (KK).