Fig. S1

Endothelial expression of Lifeact-EGFP in Tg(Fli1ep:Lifeact-EGFP) transgenic fish. (A) Maximal projection of a confocal z-stack of the head at 3.5 dpf highlighting the subintestinal vein (SIV), aortic arches (AAs) and ventral aorta (VA). Lateral view, anterior to the left. (B) 3D projection of the developing hindbrain vasculature at 53 hpf. Dorsal view, anterior to the top. CtA, central artery; PHBC, primordial hindbrain channel; BA, basilar artery. (C) Endothelial tip cell of a vascular sprout in the boxed region in B. Scale bar: 10 μm. (D) Dorsal view of the head at 3.5 dpf. Anterior to the top. MsV, mesencephalic vein; MtA, metencephalic artery; MCeV, middle cerebral vein; DLV, dorsal longitudinal vein; DMJ, dorsal midline junction; PCeV, posterior caudal cerebral vein; TCB, trans-choroid plexus branch. (E) High magnification of the TCB from D, illustrating junctional complexity of the plexus. (F) Zebrafish trunk at 3.5 dpf. The dorsal aorta (DA), intersegmental vessels (ISVs), dorsal longitudinal anastomotic vessel (DLAV), posterior cardinal vein (PCV), caudal vein (CV), subintestinal artery (SIA) and subintestinal vein (SIV) strongly express Lifeact- EGFP. (G) High magnification of the posterior end of the caudal vein plexus at 4 dpf. Intercellular junctions are distinct in both CA and CV. Scale bar: 10 μm. (H) High magnification of DLAV, arterial ISV (aISV), intersegmental lymphatic vessel (ISLV), DA, PCV and SIA at 3 dpf. Scale bar: 20 μm. (I) ISVs from 2 dpf Tg(Fli1ep:Lifeact-EGFP) embryos stained with phalloidin (magenta). Scale bar: 10 μm. (J) High magnification of boxed region in I, showing colocalisation of Lifeact-EGFP with phalloidin in an ISV (arrows).