Morphology-based ovarian stratification reflects coordinated redox imbalance and apoptosis across ovarian tissue, follicular fluid, and granulosa cells in cattle.

Physiological heterogeneity in slaughterhouse-derived bovine ovaries is a major source of variability in assisted reproductive technologies (ART). It remains unclear whether morphology-based ovarian stratification reflects coordinated functional changes across ovarian compartments. Bovine ovaries were stratified into high-quality (HQO) and low-quality (LQO) groups based on five morphological criteria. Oxidative stress and apoptosis were then evaluated in ovarian tissue, follicular fluid (FF), and granulosa cells (GCs). Across ovarian compartments, antioxidant capacity decreased by 30-60% and lipid peroxidation increased by 1.3-2.2-fold in LQO relative to HQO. Apoptotic signaling was consistently elevated in LQO relative to HQO, as indicated by increased caspase activity and an 8-13-fold increase in the BAX/BCL-2 ratio. These alterations were most pronounced in GCs, with elevated reactive oxygen species, reduced mitochondrial membrane potential, suppressed antioxidant gene expression, and increased apoptosis. These results demonstrate that morphology-based ovarian stratification reflects coordinated redox imbalance and apoptotic activation across ovarian compartments, with GCs providing the most sensitive functional readout. This approach provides a practical framework for interpreting biological variability in cattle ART studies.