Aberrant hypermaturation of neutrophils in myelopoiesis in miR-142-3p–deficient embryos. (A-B) The percentage of immature, bilobed, and multilobed neutrophils in zlyz:eGFP⁺ cells. (A) Wild-type embryos (immature neutrophils 84.3%, standard deviation [SD] = 0.76; bibilobed neutrophils 14.6%, SD = 1.80; and multilobed neutrophils 1.1%, SD = 1.08). (B) The 142ab^−/− embryos (immature neutrophils 53.2%, SD = 3.17; bibilobed neutrophils 32.9%, SD = 3.43; and multilobed neutrophils 13.9%, SD = 2.22). At least 100 cells were counted per experiment; SD, from 3 independent experiments. (C-E) Morphologic analysis of neutrophils in wild-type and 142ab^−/− embryos at 3 dpf. zlyz:eGFP⁺ cells were sorted out from wild-type or 142ab^−/− embryos and were stained with Wright-Giemsa (C). Hypersegmented neutrophils were indicated with red triangle. Relative cell size (D) and nucleocytoplasmic ratio (E) of wild-type and 142ab^−/− neutrophils were quantified by ImageJ software (version 1.47). *P < .05 or **P < .01 vs wild-type; 2-tailed Student t test. Bar represents 8 μm. (F) Sudan black staining of neutrophils recruited to neuromasts in wild-type (upper panel) and 142ab^−/− embryos (lower panel) after incubation with copper sulfate for 1.5 h. (G) Quantification of SB⁺ neutrophils recruited to neuromasts. n ≥ 15; error bars represent SEM. **P < .01 vs wild-type; 2-tailed Student t test.