Fig. 5. F-actin accumulation and lamellipodia formation in macrophages with altered Rac activity. Stage 14 embryos stained with anti-peroxidasin (red) to label the macrophages and rhodamineconjugated phalloidin (green) to label F-actin. (A) In wild-type macrophages, F-actin is localized mostly in the cell cortex. (B) Macrophages expressing Rac1^N17 show F-actin levels and distribution indistinguishable from wild type. (C) Macrophages expressing Rac1^V12 contain strongly elevated levels of F-actin. (D-F) TEM of macrophages at stage 14. (D) Macrophages expressing Rac1^N17 are round and have few or no cytoplasmic extensions. The macrophages shown are located close to the foregut and contain only few phagosomes (arrows). (E) Macrophages expressing Rac1^V12, which cluster around the foregut, show an increased number of cytoplasmic protrusions, and occasionally contain phagosomes (arrows). (F) Some of the macrophages expressing Rac1^V12 contain two nuclei (arrowheads). Bars, 10 µm (D-F).