Fig. 1

a Standard control (Std), Il6r, and Il6 morphants were detected by WISH for cmyb expression in the dorsal aorta (DA) at 36 hpf. Black arrowheads denote cmyb⁺ HSCs. b Qualitative phenotype distribution of the embryos (n above the bar graph denotes the number of embryos per group) from a scored with medium (normal) and low (down) cmyb expression. Medium, white bar; low, gray bar. ccd41:eGFP transgenic embryos were injected with Std, Il6r, and Il6 MOs and visualized at 72 hpf in caudal hematopoietic tissue (CHT). The white long line denotes cd41⁺ cells in the CHT region. d Qualitative phenotype distribution of embryos from c scored as in b. Medium, white bar; low, gray bar; absent, red bar. e Confocal tracking of HSC numbers in the floor of the DA region from individual cmyb:GFP; kdrl:mCherry double-transgenic embryos at 48 hpf. White arrowheads denote cmyb⁺, kdrl⁺ HSCs, scale bar represent 250 μm. f Enumeration of cmyb⁺, kdrl⁺ HSCs from e, bars represent the means ± SEM of Std (n = 24), Il6r (n = 24), and Il6 (n = 24) morphants. ***P < 0.001. g Std, Il6r, and Il6 morphants were examined by WISH for runx1 expression at 29 and 26 hpf, respectively. Black arrowheads represent HSCs in the floor of the DA region. h Qualitative phenotype distribution of embryos from g scored as in d. i, k Representative WISH images for rag1⁺ T lymphocyte (i) (white arrowheads) and foxn1⁺ thymic epithelial markers (black arrowheads) at 96 and 76 hpf, respectively. j, l Qualitative phenotype distribution of embryos from i, k scored as in d. m Representative images of lck⁺ T lymphocytes in Il6r and Il6 morphants compared to Std controls at 5 dpf. White dashed lines denote the thymus. n Qualitative phenotype distribution of embryos from m scored as in d. o Representative images of lyz:dsRed transgenic embryos injected with Std, Il6r, and Il6 MOs. White blocks denote the CHT and trunk regions. p Enumeration of lyz⁺ myeloid cells shown in o. Bars represent the means ± SEM of Std (n = 16), Il6r (n = 21), and Il6 (n = 24) morphants. ****P < 0.0001