In vivo SYN-NC extravasation in a zebrafish embryo tail transection model. (A) Schematic representation of the tail transection model in VEGFR2:G-RCFP transgenic zebrafish embryos transplanted with red-stained SYN-NCs. Yellow line represents the site of the cut of the tail; red arrowhead points to the site of cell injection. (B) Detail of an intact tail of a zebrafish embryo 12 hours after injection of red-stained SYN-NCs. White arrowheads point to red-stained cells inside the GFP⁺ blood vessels. (C) Detail of a cut tail of a zebrafish embryo injected with R-HMW dextran showing no vessel leakiness. (D) Details of cut tails of zebrafish embryos injected with naive (−Tat) or Tat-coated (+Tat) red-stained SYN-NCs. White arrowheads point to extravasated cells. (E) Quantification of SYN-NC extravasation by computerized image analysis. Each point is the mean ± SEM of 6 or 7 embryos from 2 independent experiments.