Fig. S2

Additional expression domains of the prox1a reporter line

(A-E) Prox1a reporter expression is shown in red, flt4:mCit expression is marked in green. (F, G) kdr-l expression domains are highlighted in red while expression of the prox1a reporter line is shown in green.

(A) Dorsal view on the anterior part of the TD which splits up in two vessels (arrow) closely aligning to the likewise bilateral PCV (arrowhead) in a 7 dpf embryo. The image has been assembled from two overlapping partial z-projections (see dotted line).

(B-E) At 24 hpf, before the onset of circulation, as yet undefined round cells within the axial vessels display expression of both markers (arrowheads in B, C). At 30 hpf, similar cells can still be seen with in the cardinal vein region (arrowhead in D, E). In addition, strong expression of the prox1a reporter is evident in a subpopulation of caudal vein cells (arrows in D, E).

(F, G) prox1a is expressed within a subgroup of caudal vein cells at 34 hpf which most likely results in the higher amounts of prox1a positive venous (arrowhead) and lymphatic secondary sprouts (arrow) in this area at 48 hpf (G). Image F is composed of two overlapping z-projections.