In the middle of the third week of embryo development, the primordial heart and vascular system begin to develop (Ozgüner and Sulak 2011). The arterial system arises from both ectoderm- and mesoderm-derived angiogenic cells. The aortic arches and the right and left dorsal aorta unite during development to form the descending aorta, which begins to form posterolateral intersegmental branches throughout the thorax (Ozgüner and Sulak 2011). As the dorsal aorta descends through the abdomen, branches to the gastrointestinal and renal systems form, including the intersegmental arteries (Ozgüner and Sulak 2011). The umbilical arteries also arise from the dorsal aorta and disconnect from it after anastomosing with the intersegmental arteries. The fifth intersegmental artery gives rise to the external iliac artery (while the umbilical artery is attached distally). Later, the umbilical artery contributes to the formation of the internal iliac artery. The common iliac arteries then arise from the proximal portion of the patent umbilical arteries (Szpinda et al. 2012).