Figure 1. flt4 positive cells sprout from the choroidal vascular plexus and migrate along blood vessels.
In all images blood vessels are highlighted in red (kdr-l:mCherry) and lympho-venous cells in green (flt4:mCitrine). (A) Overview and orientation of zebrafish embryos imaged in B–D. (B1 – B7) Time-lapse still images of lateral confocal projections of the TeO. At 56hpf strong mCitrine positive but low mCherry expressing ECs sprout from a vessel behind the PHS and migrate along the MsV (white arrow). Following initial sprouting the cell divides (B2, white and orange arrowheads). Leading and following cells appear to temporarily lose contact (B3 and B5, blue arrow). After making contact to the MsV the sprout continues migration (B4–B7). (C) Partial projection of the sprouting cells (cropping of the PHS) reveals that the migrating cells originate from the more proximal positioned CVP at around 56hpf. Sprouting cells express low mCherry but high mCitrine levels compared to the CVP (inset C’–C’’). (D) Lateral confocal projection of the head region shows that at 72hpf flt4 positive ECs (white arrowheads) form a loop aligned next to the MsVs (white arrowheads). (D’) Higher magnification of the boxed area in (D). Data are representative of at least five independent experiments. CVP, choroidal vascular plexus; EC, endothelial cell; hpf, hours post fertilization; MsV, mesencephalic vein; PHS, primary head sinus; TeO, Optic Tectum. Apostrophe in B1–B7 denotes hours.
Figure 1—figure supplement 1. flt4 positive cells develop between 56 and 72hpf.
