Analysis of the structure and function of ring canals in the follicle cells of Drosophila melanogaster

Arrested cleavage furrows called ring canals are a common feature of gamete development in many organisms and allow for direct contact of cytoplasm between cells. Ring canals in the germline of male and female Drosophila have been the focus of study for many years, but ring canals also been shown to exist in the somatically derived follicle cells that surround Drosophila egg chambers, though little about their structure or function has been elucidated. In this study, I present experiments related to the composition and function of these structures.The introduction is a review of the literature, covering Drosophila oogenesis arresting of a cleavage furrow and formation of a ring canals in female and male Drosophia germline, mouse male germline, and follicle cells and cytokinesis and abscission.In Chapter 3, I present data on the components of follicle cell ring canals. I show that 3 proteins: Pavarotti kinesin-like protein, Anillin, and Visgun---specifically localize to follicle cell ring canals. Additionally, I show that follicle cell ring canals are formed from arrested cleavage furrows, and that they have a specific localization within the apical/basal axis of the cell.In Chapter 4, I examine the morphogenesis of follicle cell ring canals. I investigate the relationship of ring canals and the cell cycle, discuss the presence and formation of tripartite ring canals, and examine how a hexagonal array of cells is obtained and maintained.In Chapter 5, I discuss possible functions of follicle cell ring canals. I examine movement of material across ring canals, and present my attempts to disrupt follicle cell ring canal function. Ongoing and future experiments are outlined in Chapter 6.Together, these studies offer insight into follicle cell ring canal structure and function, and provide a framework for continued study.