Deletion of miR-142-3p caused reduction of neutrophils in myelopoiesis. (A-B) WISH for mpo in wild-type (A) and 142ab^−/− (B) embryos at 3 dpf. (C) Quantification of mpo⁺ cell in wild-type and 142ab^−/− embryos at 3 dpf. (D-E) Sudan black staining of neutrophils in wild-type (D) and 142ab^−/− (E) embryos at 3 dpf. (F) Quantification of SB⁺ cell in wild-type and 142ab^−/− embryos at 3 dpf. (G-H) Representative stereo fluorescence images of Tg(zlyz:eGFP) (G) and 142ab^−/−; Tg(zlyz:eGFP) (H) embryos at 3 dpf. (I-J) Quantification of zlyz:eGFP⁺ cells in Tg(zlyz:eGFP) and 142ab^−/−; Tg(zlyz:eGFP) embryos at 3 dpf. (I) zlyz:eGFP⁺ cells in the whole embryos; (J) zlyz:eGFP⁺ cells in the head or CHT. n ≥ 10; error bars represent SEM. (K) Quantification of zlyz:eGFP⁺ cells in Tg(zlyz:eGFP) and 142ab^−/−; Tg(zlyz:eGFP) embryos of different stages, from 30 hpf to 96 hpf. n ≥ 10; error bars represent SEM. (L) Immunostaining shows the eGFP⁺ cells in the CHT of Tg(zlyz:eGFP) (upper panel) and 142ab^−/−; Tg(zlyz:eGFP) (lower panel) embryos at 3 dpf. Macrophage-like cell is indicated by yellow triangle (lower panel). (M) WISH shows the mpeg1 expression in the CHT of wild-type (upper panel) and 142ab^−/− embryos (lower panel) at 3 dpf. (N-S) Double immunostaining of zlyz:eGFP and BrdU shows a reduced proliferation of zlyz:eGFP⁺ cells in the CHT of 142ab^−/− embryos at 3 dpf. (T) Quantification of the percentage of BrdU⁺ cells in the 3 dpf zlyz:eGFP⁺ population. n ≥ 8; error bars represent SEM. **P < .01; 2-tailed Student t test.