Fig. 1: Global deletion of Elmo2 leads to carotid artery aneurysm and embryonic lethality.

a Representative images of control and Elmo2^−/− embryos at different developmental stages showing hemorrhages in the cervical region and subcutaneous edema (white arrowheads) in knockout mice. Scale bars, 2 mm. b Cross-section of an E12.5 Elmo2^+/− embryo stained with X-gal (blue) and Eosin (red) showing expression of Elmo2 in the cervical region. Higher magnification (bottom panel) shows relevant vascular structures: dorsal aorta (DA), third pharyngeal arch artery (3^rd PAA), jugular vein (JV), and jugular lymph sac (JLS). Scale bars, 2 mm. c Quantitation of area and perimeter of the 3^rd PAA in control and Elmo2^-/- E12.5 embryos. Mean ± SEM, n = 8. Welch’s t-test (area) and unpaired t-test (perimeter). d Quantitation of area and perimeter of the carotid artery (CA) in control and Elmo2^-/- E13.5 embryos. Mean ± SEM, n = 7. Welch’s t-test. e Confocal images of control and Elmo2^−/− E12.5 embryos stained for nuclei (DAPI, blue), veins and capillaries (EMCN, green), vascular smooth muscle cells (VSMCs, αSMA, red), lymphatic endothelial cell (EC) nuclei (Prox1, magenta) and ECs (CD31, gray). Higher magnification images correspond to the insets (outlined by white dashed line) in the respective overview images and highlight the 3^rd pharyngeal arch artery (PAA), jugular vein (JV), and jugular lymph sac (JLS). Scale bars, 200 µm (overview) and 50 µm (higher magnification). f Representative light sheet microscopy 3D images of control and Elmo2^−/− embryos at different developmental stages stained for ECs (CD31, red) and VSMCs (αSMA or SM22α, gray). Vascular structures of interest are indicated: pharyngeal arch arteries (PAA) or carotid arteries (CA). The schematic on the right shows the orientation of the embryos and the approximate area imaged in the respective developmental stages. Scale bars, 300 µm in each dimension.