Arterial and venous vessels are required for modulating developmental relocalization and laterality of the interrenal tissue in zebrafish.

During zebrafish embryogenesis, the endothelium signals to emergent bilateral interrenal primordia to converge toward the midline, yet the merged interrenal tissue has been found to be situated lateral to the midline. We show in this study that bilateral interrenal tissue clusters fused at the central midline, before relocating laterally to be juxtaposed between the dorsal aorta and the posterior cardinal vein. In ets1b morphants where the midtrunk vasculature failed to assemble, various degrees of interrenal fusion defects were displayed, and the interrenal laterality was lost. As either arterial or venous endothelium was specifically reduced, the interrenal tissue was defective in its relocalization and laterality, yet remained closely associated with the malformed vasculature. Our results showed evidence to support that assembly of the axial artery and vein, and its resulting vascular topology at the midtrunk, is required for patterning relocalization and laterality of the interrenal tissue after the initial medial fusion.