Border Cell Migration: A Model System for Live Imaging and Genetic Analysis of Collective Cell Movement

Abstract

Border cell migration in the Drosophila ovary has emerged as a genetically tractable model for studying collective cell movement. Over many years border cell migration was exclusively studied in fixed samples due to the inability to culture stage 9 egg chambers in vitro. Although culturing late-stage egg chambers was long feasible, stage 9 egg chambers survived only briefly outside the female body. We identified culture conditions that support stage 9 egg chamber development and sustain complete migration of border cells ex vivo. This protocol enables one to compare the dynamics of egg chamber development in wild-type and mutant egg chambers using time-lapse microscopy and taking advantage of a multiposition microscope with a motorized imaging stage. In addition, this protocol has been successfully used in combination with fluorescence resonance energy transfer biosensors, photo-activatable proteins, and pharmacological agents and can be used with wide-field or confocal microscopes in either an upright or an inverted configuration.

Fig. 1

Anatomy of the Drosophila ovary. Top—Schematic drawing of a pair of ovaries dissected from female fruit fly. A schematic drawing of an enlarged single ovariole containing egg chambers of the indicate stages of development. Bottom—DIC image of an ovariole with similar stages of egg chamber development

Fig. 2

Ovary dissection technique: Schematic representation of egg chamber dissection. (a) The female fly should be immobilized on its back using the left forceps. The right forceps are used to pinch the soft cuticle of the ventral side of the abdomen. (b) Pull the cuticle toward the right (arrow), revealing the ovaries. Grasp the common oviduct with the right forceps and pull to the right (arrow) to free the ovaries from the carcass. (c) Immobilize the ovary pair by pinching the oviduct using the left forceps. Use the right forceps to grasp the tip of an ovariole and slowly pull to the right (arrow). (d) Repeat until multiple ovarioles have been freed from the sheath