In vivo imaging of neutrophilic granulocytes by video-enhanced DIC microscopy. The nucleus of each neutrophil, whenever visible, is indicated by a black asterisk. (A) 48 hpf: a neutrophil migrating within the epidermis (at this stage still a monolayer). Time is indicated in minutes and seconds. In this 24-minute sequence, the neutrophil moves successively along 3 long epidermal cells (e, e′ and e″), at a mean velocity of 10 μm/min; the worm-like elements visible in these cells are mitochondria. See also Video S1. (B) 50 hpf: a neutrophil with visibly bilobed nucleus in addition to its granules, in contact with a Schwann cell (with white asterisk on its nucleus) wrapped around the posterior lateral line nerve. (C) 48 hpf: 2 neutrophils on the anterior aspect of the pericardium. (D) 50 hpf: still image from Video S2. A neutrophil interacting with a macrophage, itself interacting with 3 dying erythrocytes in the yolk sac circulation valley. (E) 56 hpf: a macrophage that accumulated methylene blue from the outer medium, and 3 granulocytes, in the CHT. See also Video S3. (F) 5 dpf: 2 neutrophils along a blood vessel in the ventral head. (G) 56 hpf: a neutrophil in the mesenchyme along the retinal pigment cell layer. (H) 7 dpf: a neutrophil near a neuromast of the ventral head (white asterisk). n indicates neutrophilic granulocyte; Mφ: macrophage; e-e′-e″, bulk epidermal cells; m, epidermal mucous cell; er, degenerating primitive erythrocytes; pll, posterior lateral line nerve; c, cartilage; mf, cephalic muscle fibers; s, somitic muscle; r, retina; and rpc, retinal pigment cell layer. Scale bars, 10 μm.