Ultrastructure of correlated macrophages and neutrophils in 3D serial block-face SEM images. (A) High-resolution CLSM image of an infected tail fin after live-cell imaging and fixation. (B) SBFSEM image of the same region as in A showing correlated macrophages (arrowheads) and neutrophils (arrows). (C) Higher magnification SBFSEM images of the two macrophages and two neutrophils indicated in A and B. (D) Frames from time-lapse imaging showing the macrophages and neutrophils in C at previous time points. The macrophage (M1) with a fragmented nucleus contains a high Mm content, indicated by the asterisk in C. This macrophage phagocytized the bacterial content ~30min before fixation. Macrophage M2 contains a large aggregate of Mm which was phagocytized Mm ~1.5h before fixation. Neutrophil N1 shows a rapid signal disappearance ~45min before the fixation (D). Neutrophil N2 was recruited to the bacterial aggregate ~30min before fixation (D). Scale bars: 10µm (A-C); 2µm (D).