Figure 1.—

Summary of Drosophila oogenesis. Drosophila oogenesis begins at the anterior-most end of an ovariole in the germarium where two germ-line stem cells divide asymmetrically to produce daughter cysts. These cysts undergo four rounds of incomplete mitosis to produce a 16-cell cyst that is then encapsulated by follicle cells arising from 2 follicle stem cells. The follicle cells continue to divide until stage 6. Prior to stage 6 egg chambers remain spherical; beginning at stage 6, egg chamber elongation occurs along the anterior–posterior axis, giving rise to elongated mature eggs. (A) Schematic diagram of a single ovariole. (B) Wild-type ovariole stained with phalloidin revealing elongation of egg chambers as they age. (C) pak mutant ovariole showing failure of egg chamber elongation and degradation of oldest chamber. Bar: 50 μm.