Fig. 5. Vascular abnormalities in Hhex^–/– mice at E13.5. (A,B) Transverse sections through the neck region of E13.5 embryos show massive dilation of the internal jugular vein in Hhex^–/– embryo compared to wild-type embryo. A and B are shown at the same magnification. Other examples of abnormal vascular structures include enlarged intercostal vessels (arrows) (C,D) and massive vascular lake (arrow) in the region of the septum transversum (F) in place of normal liver tissue and vascular structures (E). CCA, common carotid artery; IJV, internal jugular vein; TYR, thyroid; IA, intercostal artery.