Oocyte–granulosa cell communication networks in follicular development and ovarian disorders: mechanisms and translational perspectives

Bidirectional communication between the oocyte and surrounding granulosa cells (GCs) coordinates follicular development, oocyte maturation, and reproductive outcomes. This review frames oocyte-GC communication as an integrated network linking structural connectivity, metabolic cooperation, second-messenger regulation, cumulus expansion, and oocyte-derived feedback. We emphasize how these mechanisms are reshaped in polycystic ovary syndrome (PCOS), primary ovarian insufficiency (POI), and endometriosis-associated infertility, and we distinguish established mechanisms from emerging or disease-specific hypotheses. The review identifies communication nodes relevant to interpreting oocyte quality and assisted reproductive technology outcomes.