Fig. 2. Migrating macrophages extend lamellipodia and filopodia. Time-lapse sequences of live embryos in which macrophages are labeled with gcm-Gal4 UAS-mGFP. (A-J) Focus is on macrophages migrating between the ventral epidermis and the ventral cord in stage 14 embryos. (K-P) Shown is a macrophage migrating over the yolk sac underneath the amnioserosa in a stage 13 embryo. Migrating macrophages extend wide lamellipodia (arrows in D,G,K). These protrusions are very dynamic and quickly extend, retract and change shape (A-F and I-J). The extension of lamellipodia occurs in the direction of cell movement (e.g. K-M). A macrophage extends a single lamellipodium at a given time. In addition to lamellipodia, macrophages extend thin needle-like protrusions (arrowheads in C,G,J). These filopodia are also very dynamic (B,C). Occasionally, part of the trailing end of the cell is seen to pinch off (K-P). (Q) TEM of a stage 14 wild-type embryo showing a macrophage extending a lamellipodium (arrow). Inside the cell, vesicles containing apoptotic bodies (dark inclusions) can be seen. (R) Whole mount stage 14 gcm-Gal4 UAS-lacZ embryo stained with anti-ß-Gal antibody (red) and anti-peroxidasin (green). All bars, 10 µm.