Fig. 7

Treatment of embryos with the VEGFR tyrosine kinase inhibitor vatanalib from 20 to 55 hpf caused severe defects in the pharyngeal vasculature. tg(tg:mCherry;kdrl:EGFP) embryos treated with vatanalib (5 µM) or DMSO (0.1%) were stained by IF for mCherry (red) and GFP (green) and were analyzed by confocal microscopy for thyroid and vessel defects at 80 hpf. Note that some embryos were also stained for cardiac troponin T (white). (A) Analysis of DMSO-treated embryos at 80 hpf showed a normal vascular development with the thyroid tissue showing a progressive expansion along the pharyngeal midline. ((B)–(F)) Vatanalib treatment resulted in a variety of defects in ventral aorta (VA), hypobranchial artery (HA) and aortic arch artery (aa1, aa3) formation. While a highly dysplastic HA could be identified in many embryos (see (B) and (C)), in some embryos it was not possible to unequivocally identify the vessels present in the highly irregular networks close to the outflow tract (see (D)). The thyroid tissue of vatanalib-treated embryos was always located in close vicinity to vessels so that any deviation of thyroid tissue from the midline was associated with abnormal vessel localization. ((E)-(F)) Notably, whenever the HA could be identified, thyroid tissue was found associated with it. Scale bar: 50 μM).