Tbx1 colocalizes with LEC-specific markers in mesenteric lymphatic vessels. (A and B) LacZ reporter activity revealed by X-gal staining (blue) colocalizes with anti-Vegfr3 immunostaining (brown) in mesenteric lymphatic vessels (arrows) of Tbx1^lacZ/+ embryos at E13.5. The boxed area in A is magnified in B. (C and D) Colocalization of LacZ reporter activity and anti-Lyve1 immunostaining in Tbx1^lacZ/+ embryos at E14.5 (C) and E16.5 (D). (C, inset) X-gal staining on an adjacent section is shown. (E and F) Tbx1 protein is expressed in mesenteric LECs at E16.5 (E, arrowheads) and has a similar distribution to the LacZ reporter activity at this stage (F). A, mesenteric artery; V, mesenteric vein; L, lymphatic vessel. Bars, 100 µm.