Cultivating a Support Network: Granulosa Cells and the Needed Knowledge on their Role in Oocyte Maturation

Maintaining and restoring full developmental competence of oocytes after a process of cryopreservation to preserve fertility is a growing concern in the field of assisted reproductive technologies (ART). Unfortunately, attempts so far have been characterized by low quality and a poor yield of live births. A promising avenue of research is to replicate the microenvironment of the follicles to achieve careful cryopreservation and successful in vitro maturation. A key step for this is to understands the interactions between somatic granulosa cells and the oocyte that are required for maturation and developmental competence. In the present work we present a succinct review of these molecular interactions, including endocrine and paracrine signaling, gene regulation and cell communication. We focus primarily on the role of both types of granulosa cells: mural granulosa cells, which perform endocrine functions, including hormone production and cumulus cells, which provide metabolic support and establish bi-directional communication with the oocyte through various pathways, including direct contact. The coordinate development of both granulosa cell types is necessary to fulfill oocyte requirements. Being able to reproduce those conditions in vitro could lead to successful oocyte maturation and positive fertilization outcomes.