Effects of maternal liver abnormality on maturation of bovine oocytes.

In cattle, maternal metabolic health has been suggested to influence oocyte and embryo quality. Here, we examined whether maternal liver abnormalities affected oocyte maturation by screening meiotic maturation, spindle morphology, actin filaments, and lysosomes. In oocytes from the abnormal liver group, the maturation rate (80.2%) was significantly lower compared to a control group with healthy livers (90.8%; P < 0.05). Mean spindle area in oocytes of the abnormal group (50.4 ± 3.4 μm) was significantly larger than in the control (40.8 ± 1.6 μm; P < 0.05). Likewise, mean spindle width in the abnormal group (8.8 ± 0.3 μm) was significantly larger than in the control group (7.8 ± 0.2 μm; P < 0.05). The proportion of cells with correctly aligned chromosomes in the abnormal group (48.0%) was significantly lower than in the control (78.3%; P < 0.05). The number of cortical actin filaments in mature oocytes of the abnormal group (299.3 ± 3.7) was significantly lower than in the control (314.7 ± 3.2; P < 0.05). The number of lysosomes in mature oocytes of the abnormal group (1363.6 ± 39.0) was significantly higher than in the control (1123.4 ± 26.3; P < 0.05). In conclusion, our findings indicate that the quality of matured oocytes is lower in cattle with liver abnormalities than in healthy cattle.