Defective definitive hematopoiesis results from the increased apoptosis of HSPCs of bcas2^−/−zebrafish. (A-L) Double immunostaining of cmyb: EGFP and TUNEL at 3 dpf showed an increased apoptosis of HSPCs in the CHT of bcas2^−/− mutants that was more prevalent at 4 dpf. Scale bars, 50 μm. (M-N) Quantification of the percentage of the apoptosis of HSPCs in sibling and bcas2^−/− mutants at 3 dpf and 4 dpf indicates increased apoptosis of HSPCs in bcas2^−/− embryos. For the quantitative analysis, at least 6 embryos were analyzed for each experimental group. Data are represented as mean ± SD. ***P < .001.