Bidirectional communication in oogenesis: a dynamic conversation in mice and Drosophila

In most animals, the oocyte is the largest cell by volume. The oocyte undergoes a period of large-scale growth during its development, prior to fertilization. At first glance, tissues that support the development of the oocyte in different organisms have diverse cellular characteristics that would seem to prohibit functional comparisons. However, these tissues often act with a common goal of establishing dynamic forms of two-way communication with the oocyte. We propose that this bidirectional communication between oocytes and support cells is a universal phenomenon that can be directly compared across species. Specifically, we highlight fruit fly and mouse oogenesis to demonstrate that similarities and differences in these systems should be used to inform and design future experiments in both models. Bidirectional communication between oocytes and support cells is essential for oocyte development and maturation. This dynamic is a common feature of both mouse and Drosophila oogenesis and is likely conserved in other animals.Physical cell structures facilitate the exchange of nutrients, growth factors, metabolites, and organelles between the oocyte and support cells in both the mouse and Drosophila. In the mouse, communication occurs through transzonal projections and the secretion of factors within the extracellular space. In Drosophila, factors are exchanged through ring canals.Although it is well established that the mouse oocyte drives bidirectional communication with granulosa cells, the Drosophila oocyte until recently was considered a passive recipient of nurse cell products. Emerging studies show that the Drosophila oocyte also engages in communication with these support cells.