Supplementary Figure 3: Thoracic surgical access.

a. Euthanized mouse pinned on the surgical table. Dotted lines indicate skin incisions. b. Subcutaneous dissection reveals the neck, the thoracic, and abdominal walls. c. Section of the pectoralis muscles (blue arrowheads) and incisions through the eight intercostal spaces (blue arrows). d. Intercostal incisions are united by sectioning the sternum horizontally (dotted line). e. Sternotomy (dotted line 1) and sectioning of the ribs along the thoracic wall (dotted lines 2 and 3). f. Pinning the sectioned thorax reveals the thymus (1), heart (2), lungs (3), and cava vein (4). g. Excision of the thymus reveals the aorta (1), brachiocephalic artery (2), left common carotid artery (3), left subclavian artery (4), internal mammary arteries (5), and brachiocephalic veins (6). h. Elevating the brachiocephalic veins allows clear differentiation of the major arteries (numbering equal to g). (Scale bars, 2 mm unless otherwise stated).