Neutrophil maturation is attenuated in cebp1^smu1/smu1 mutants. (A-B) WISH of lyz expression in 2-dpf siblings and cebp1^smu1/smu1 mutants. (C-D) WISH of srgn expression in 2-dpf siblings and cebp1^smu1/smu1 mutants. (E-H) SB staining of 36-hpf (E-F) and 2-dpf (G-H) siblings and cebp1^smu1/smu1 mutants. (I-J) In vivo VE DIC microscopy reveals scant granule in neutrophils in 2 dpf Tg(mpx:GFP);cebp1^smu1/smu1 transgenic mutants (J) compared with siblings (I). Left panels, Bright-field DIC images; right panels, overlays of bright-field DIC images with corresponding GFP fluorescent images. Blue arrowheads identify granules contained by neutrophils (white arrows) expressing GFP. (K) Quantifications of WISH, SB staining, and DIC analysis (Student t test, ***P < .001, ****P < .0001; WISH and SB, n ≥ 23; DIC, n ≥ 56). (L) May-Grünwald-Giemsa staining of neutrophils in 3-dpf embryos (left) and neutrophils were quantitated by morphology (right) (Student t test, *P < .05, n ≥ 500). Scale bars, 200 μm (E-H) and 5 μm (I, J, L).