Fig. 1. Rab11 is enriched on the fusome of GSCs and germline cysts. (A) Diagram of the Drosophila germarium. Niche terminal filament (TF), cap (CC), and escort stem (ESC) cells are shown in gray. The fusome (red) lies at the anterior cortex of germline stem cells (GSCs, black) and extends throughout the cytoplasm of germline cysts (white). Oocyte (green); somatic follicle cells (FC); ring canals (blue crescents). (B-E) Region 1 of a wild-type germarium immunostained for E-cadherin (green), Rab11 (red), and the fusome marker -Spectrin (blue). Merged image (E). Anterior is to the left in this and all subsequent figures. A single GSC is outlined in B, with the break in the tracing (dashed line) revealing strong E-cadherin staining at the GSC-cap cell interface. The smaller dot of E-cadherin staining (arrow) superimposes with Rab11 on the fusome (arrows in C and D). (F-H) Wild-type germarial regions 1 and 2 immunostained for Rab11 (red) and -Spectrin (blue). Merged image (G). Strong accumulation of Rab11 is apparent on the GSC (arrowhead) and fusome of the germline cyst (arrow). (I,J) Mosaic germarium immunostained for nuclear GFP (nGFP, green), Rab11 (red) and -Spectrin (blue). Note the absence of Rab11 protein in the rab11-null cells, which are marked by the absence of nGFP in this and all subsequent images. (J) Rab11 channel only. (K,L) Germarial region 1 of rab11::GFP transgenic germarium immunostained for GFP (red) and -Spectrin (blue). Arrowheads indicate strong Rab11::GFP expression on the fusome. Scale bars: 10 µm.