Characteristics of collagen in ovarian extracellular matrix and its relationship with the development of primordial follicles up to ovulation.

The extracellular matrix (ECM) is a dynamic network of proteins and biomolecules that performs essential structural and signaling functions in mammalian ovarian physiology. In addition to modulating processes such as cell adhesion, migration, and differentiation, the ECM is actively involved in regulating tissue stiffness, a physical property directly involved in follicle activation and development. Among its components, collagen fibrils stand out as determinants in maintaining ovarian architecture and remodeling the follicular microenvironment throughout folliculogenesis. Evidence from in vivo and in vitro models shows that changes in the composition, organization, and distribution of collagen fibrils, particularly types I, III, IV, and VI, influence the transition from primordial follicles to growth stages and are involved in the intense remodeling that occurs during ovulation and reproductive senescence. In this review, we discuss the central role of collagen fibrils in regulating ovarian cortex stiffness and its relationship to follicular growth, highlighting cellular and molecular mechanisms associated with ECM remodeling in different species and physiological contexts.