Regionally Distinct Modes of Intestinal-Systemic Vascular Connections in Developing Zebrafish.

Connecting the intestinal vasculature with the pre-existing systemic circulatory system is vital for nutrient absorption and blood transport for detoxification in the liver. However, the cellular processes underlying this connection remain unclear. Using genetically modified zebrafish models and in vivo imaging, we visualized that the supra-intestinal artery (SIA) connected to the pre-existing dorsal aorta (DA) in two distinct regions, the anterior and posterior. We found that endothelial cells migrated out of the DA and formed the anterior SIA-DA junction, whereas endothelial cells sprouted from SIA and connected to the DA in the posterior region. Pharmacological and genetic analyses revealed that activin receptor-like kinase 1 (ALK1) signaling was required for the SIA-DA connections. The present study provides new insights into the cellular phenomena and regulatory mechanisms of intestinal vascular development.