Multi-contrast optical coherence tomography for <i>in vivo</i> visualization and quantification of vascular features and collagen in mouse ovaries in aging

Multi-contrast optical coherence tomography (MC-OCT), incorporating optical coherence tomography angiography (OCTA) and polarization-sensitive OCT (PS-OCT), offers a powerful non-invasive approach for interrogating ovarian microvascular and extracellular matrix (ECM) remodeling in vivo . However, its application to ovarian aging has remained largely unexplored. Here, we establish and validate MC-OCT as a robust imaging platform for visualizing and quantifying age-related changes in vascular architecture and collagen organization in mouse ovaries. Using in vivo OCTA, we demonstrate a progressive decline in ovarian microvascular density, complexity, and connectivity with advancing age. Complementary PS-OCT imaging reveals increased collagen-associated birefringence, indicative of fibrotic ECM remodeling. Quantitative OCT-derived metrics show strong agreement with histological validation using immunohistochemistry, second harmonic generation microscopy, and Sirius Red staining, confirming the accuracy and reproducibility of MC-OCT measurements. Importantly, MC-OCT enables longitudinal, real-time assessment of ovarian structure without tissue disruption, allowing detection of age-dependent remodeling that is not accessible with conventional ex vivo methods. Together, these findings establish MC-OCT as a sensitive and reliable tool for non-destructive evaluation of ovarian vascular and fibrotic changes, providing a valuable platform for studying ovarian aging and assessing interventions aimed at preserving reproductive health.