tfec is highly enriched in caudal endothelial cells. (A-B) Representative embryos after in situ hybridization (ISH) of tfec on WT embryos at 20 and 24 hpf. (C-D) ISH of tfec (black) and flk1 (red) on WT embryos at 20 and 24 hpf. (E-F) ISH of tfec (black: PBI and neural crest) and runx1 (black: aorta) at 24 hpf on either mindbomb^−/− (loss of runx1 staining) or siblings with WT phenotype (normal runx1 staining). (G-H) ISH of tfec (black) and gata1 (red) on either cloche^−/− (loss of gata1 staining) or WT sibling (normal gata1 staining). Prime panels depict the region indicated by the dashed outline box. The numbers in the bottom right corner (here and in following figures, unless otherwise stated) of the image indicate the number of embryos with the represented phenotype out of the total number of embryos. (I) qPCR data examining tfec expression (using primers that recognize all transcripts) in FACS-sorted cells from flk1:eGPF embryos. eGFP-negative cells from the whole embryo, eGFP-positive cells from the whole embryos, eGFP-positive cells from dissected heads and trunks (heads), or eGFP-positive cells from dissected tails (tails) were sorted from 26-hpf embryos. Statistical analysis was completed using an un-paired Student t test. Data represents mean ± SEM ****P < .001.