Figure 1. Actin remodeling is temporally and spatially regulated during mid-oogenesis.

(A–G) Maximum projections of 3–5 confocal slices of fixed and stained wild-type (yw) follicles, staged as indicated, taken at 20X magnification. Anterior is to the left. F-actin (phalloidin) = white, DNA (DAPI) = cyan. (A-B’) S9. (C) S10A. (D-F) S10B. (G) S11. During S9, the border cells and main-body follicle cells are undergoing migration and the nurse cell cytoplasm is largely devoid of actin filament structures (A-A’), but occasionally there are actin filament and aggregate structures emanating from the ring canals in the posterior nurse cells adjacent to the oocyte (B-B’). Both the border cell and main-body follicle cell migration are completed by S10A and the nurse cells lack cytoplasmic F-actin structures (C). During S10B, dynamic actin remodeling is occurring within the nurse cells. Actin filament bundles first form in the posterior nurse cells, at the nurse cell-oocyte boundary (D). These bundles continue to elongate and bundle formation initiates on all of the nurse cell membranes that are directly attached to their neighboring nurse cell by a ring canal (E). At the completion of S10B the bundles are uniformly distributed along the nurse cell membranes and extend all the way to the nucleus (F). During S11, the cortical actin contracts to squeeze the cytoplasmic contents of the nurse cells into the growing oocyte (G). Scale bars = 50 μm, except in A’ and B’ where scale bars = 10 μm.