Confocal microscopy of actin filaments surrounding endocytosed organisms. Endothelial cells were incubated for 45 minutes with A fumigatus H237 conidia (A-B) or germ tubes (C-D), and then stained for filamentous actin. (A,C) Confocal images of the filamentous actin. (B,D) Differential interference contrast images of the same microscopic fields shown in panels A and C, respectively. Arrows indicate endothelial cell actin polymerizing around the organisms (A,C) and the organisms themselves (B,D). Original magnification × 1000.