Live imaging of epithelial phagocyte differentiation in the Drosophila ovary reveals transient and novel behaviors.

The transformation of epithelial cells into non-professional phagocytes (NPPs) is a conserved and versatile adaptation that occurs in response to immune challenges, tissue remodeling and apoptotic debris clearance. In the Drosophila melanogaster ovary, follicle cells (FCs) acquire phagocytic capabilities under stress, providing a powerful model to study this process. Using time-lapse live imaging, we captured dynamic behaviors associated with FC-to-NPP differentiation that are too transient to detect by static imaging. Our approach confirmed established features, including germline cell death, cytoplasmic expansion and debris engulfment, and revealed previously unrecognized capabilities. These include a gradual increase in JNK pathway activation, after which NPPs exhibit collective migration toward dying germline cells, epithelial delamination, long-range target capture through pseudopodial extensions and the engulfment of neighboring FCs. These findings demonstrate that epithelial-derived NPPs can perform complex phagocytic tasks typically attributed to professional phagocytes, such as macrophages. Our work establishes the Drosophila ovary as a robust in vivo system to uncover conserved and novel aspects of epithelial plasticity and phagocytic function, particularly those involving transient behaviors missed by fixed-sample analyses.